# GCN_circulars

GRB_name: GRB130418A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14403
SUBJECT: GRB 130418A: Swift-XRT refined Analysis
DATE:    13/04/20 05:05:40 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf
of the Swift-XRT team:

We have analysed 2.7 ks of XRT data for GRB 130418A (De Pasquale  et
al. GCN Circ. 14377),  from 119 s to 15.6 ks after the BAT trigger.
The data comprise 262 s in Windowed Timing (WT) mode (the first 9 s
were taken while Swift was slewing) with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Evans et al. (GCN. Circ 14383).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.72 (+/-0.11), followed by a break at T+801 s to an
alpha of 1.51 (+0.54, -0.30).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.24 (+/-0.06). The
best-fitting absorption column is  2.9 (+7.3, -2.9) x 10^20 cm^-2, at a
redshift of 1.218, in addition to the Galactic value of 2.7 x 10^20
cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index
of 1.70 (+0.24, -0.23) and a best-fitting absorption column of 2.6
(+3.0, -2.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum  is 4.2 x 10^-11
(4.8 x 10^-11) erg cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Galactic foreground: 2.7 x 10^20 cm^-2
Intrinsic column:    2.6 (+3.0, -2.5) x 10^21 cm^-2 at z=1.218
Photon index:      1.70 (+0.24, -0.23)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00553847.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14404
SUBJECT: GRB 130418A: Continued RATIR Optical and NIR Observations
DATE:    13/04/20 07:11:53 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Subject: Subject: GRB 130418A: Continued RATIR Optical and NIR Observations

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We re-observed the field of GRB 130418A (De Pasquale, et al., GCN 14377)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico
Nacional on Sierra San Pedro Mrtir from 2013/04 20.14 to 2013/04 20.26 UTC
(32.30 to 35.30 hours after the BAT trigger), obtaining a total of 2.13
hours exposure in the r' and i' bands and 0.89 hours exposure in the Z, Y,
J, and H bands.

Relative to our observations last night (GCN 14388), the GRB afterglow has
faded significantly, by approximately 3 magnitudes in all bands.  In
comparison with SDSS DR8 and 2MASS, we find:

  r'    21.74 +/- 0.12
  i'    21.80 +/- 0.16
  Z     21.52 +/- 0.26
  Y     21.01 +/- 0.21
  J     20.65 +/- 0.17
  H     20.98 +/- 0.35

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertainties are 1-sigma.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14405
SUBJECT: GRB 130420A: Faulkes Telescope North candidate
DATE:    13/04/20 07:46:12 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB),
D. Kopac, A. Gomboc (U. Ljubljana), on behalf of a
large collaboration report:

The 2-m Faulkes Telescope North automatically began observing
GRB 130420A at 4.35 minutes from the Swift/BAT trigger time.
The automatic LT-TRAP procedure identified a bright uncatalogued
object at the following position:

RA=   13:04:25.57
Dec= +59:25:26.7

(J2000).
Its magnitude is estimated to be 15.9 in the R band.


GRB_name: GRB130420A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14406
SUBJECT: GRB 130420A: Swift detection of a burst with an optical counterpart
DATE:    13/04/20 07:50:15 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. J. Page (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), S. R. Oates (UCL-MSSL) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 07:28:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130420A (trigger=553977).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 196.100, +59.424 which is 
   RA(J2000) = 13h 04m 24s
   Dec(J2000) = +59d 25' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a very gradual beginning 
and a large peak at T+100 seconds.  The total duration was about 200 sec.  
Because of the gradual beginning, the trigger was an image rather than a rate
trigger.  The peak count rate was ~3985 counts/sec (15-350 keV), at ~110 sec 
after the trigger. 

The XRT began observing the field at 07:40:44.8 UT, 735.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 196.1061, 59.4241 which
is equivalent to:
   RA(J2000)  = 13h 04m 25.46s
   Dec(J2000) = +59d 25' 26.8"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 11 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.26
x 10^20 cm^-2 (Kalberla et al. 2005). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 738 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 13:04:25.57 = 196.10654
  DEC(J2000) = +59:25:26.9  =  59.42415
with a 90%-confidence error radius of about 0.75 arc sec. This position is 5.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.22 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01. 

Burst Advocate for this burst is M. J. Page (m.page AT ucl.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130420A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14407
SUBJECT: GRB 130420A: ROTSE-III Detection of Optical Counterpart 
DATE:    13/04/20 08:08:48 GMT
FROM:    Tolga Guver at UA  <tolga@physics.arizona.edu>

GRB 130420A: ROTSE-III Detection of Optical Counterpart 

T. Guver (Sabanci U), report on behalf of the ROTSE collaboration: 
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 130420A (Swift trigger 553977). The first image was at 07:29:51.5 UT, 82.0 s after the burst (7.5 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 15.5 magnitude, fading source with coordinates: 

     13:04:25.5      +59:25:27.2    (J2000), with positional uncertainty of 1" or better

start UT mag mlim(of image) 
---------------------------------- 
07:34:12.7 15.5 16.5
This source is not visible in DSS (second epoch), 2MASS or the MPChecker database.

A jpeg image is available at http://www.rotse.net/images/gsq553977_3b03_img.jpg Note that the object marked 91 is the candidate in question.

Continuing observations are in progress.


GRB_name: GRB130420A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14408
SUBJECT: GRB 130420A: PAIRITEL NIR detections
DATE:    13/04/20 08:16:50 GMT
FROM:    Adam Morgan at U.C. Berkeley  <qmorgan@gmail.com>

A. N. Morgan (UC Berkeley) reports:

We observed the field of GRB 130420A (Page et al., GCN 14406) with the 1.3m
PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2013-Apr-20
07h37m23s UT, 8.9 minutes after the Swift Trigger.  In  mosaics (effective
exposure time of ~10 minutes) taken simultaneously in the J, H, and Ks
filters, we detect the optical afterglow (Guidorzi et al., GCN 14405; Page
et al., GCN 14406; Guver et al., GCN 14407).

The preliminary photometry yields:

post burst
t_mid (hr) exp.(m)  filt  mag   m_err
0.28       9.75     J     15.59  0.05
0.28       9.75     H     14.99  0.07
0.28       9.75     Ks    14.13  0.12

Observations are ongoing. All magnitudes are given in the Vega system,
calibrated to 2MASS. No correction for Galactic extinction has been made to
the above reported values.


GRB_name: GRB130420A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14409
SUBJECT: GRB 130420A: RATIR Optical and NIR Observations
DATE:    13/04/20 11:56:25 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB),
Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), 
and Harvey Moseley (GSFC) report:

We observed the field of GRB 130420A (Page, et al., GCN 14406) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/04 20.41 to 2013/04 20.45 UTC (2.48
to 3.38 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r' and i' bands and 0.14 hours exposure in the Z,
Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with SDSS DR8
and 2MASS, we find:

r' 19.81 +/- 0.02
i' 19.41 +/- 0.02
Z 19.37 +/- 0.06
Y 18.99 +/- 0.07
J 19.16 +/- 0.07
H 18.87 +/- 0.11

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertainties are 1-sigma.

Comparison to the earlier photometry of Morgan et al. (GCN 14408) shows that this source has faded by about 2.5 magnitudes in J and H.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro 
Mrtir.
-- 
Dr. Alan M. Watson
Instituto de Astronoma
Universidad Nacional Autnoma de Mxico


GRB_name: GRB130420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14410
SUBJECT: GRB 130420A: T21 optical observations
DATE:    13/04/20 13:06:20 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:

We have detected GRB 130420A optical afterglow at iTelescope 
Observatory T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph
and FLI ProLine PL6303E CCD. Two unfiltered images with 600
sec exposure time were made.

The afterglow was detected at following position RA 13:04:25.51
and DEC +59:25:27.2.

The following magnitudes were obtained from the observations using 
NOMAD1 1494-0215473 (R=16.220) as the comparison:

Tmid(sec)+T0  Filter         Exp. time   Mag           Mag err.  Limit
7258                unfiltered   600            19.49CR   0.20        20.60
7885                unfiltered   600            19.61CR   0.24        20.48


GRB_name: GRB130420B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14411
SUBJECT: GRB 130420B: Swift detection of a burst
DATE:    13/04/20 13:14:19 GMT
FROM:    David Burrows at PSU/Swift  <burrows@astro.psu.edu>

S. R. Oates (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC),
D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), S. T. Holland (STScI),
N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU) and
E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift
Team:

At 12:56:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130420B (trigger=553996).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 183.120, +54.386 which is 
   RA(J2000) = 12h 12m 29s
   Dec(J2000) = +54d 23' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 12:57:25.6 UT, 54.5 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. About 8 seconds of data were obtained in WT mode before Swift 
slewed away from the field, indicating a bright X-ray source in the field, 
but no position is available from the WT data. No XRT position will be 
available until data from the second orbit are processed. 

UVOT took a finding chart exposure of 8 seconds with the White filter
starting 57 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.02. 

Burst Advocate for this burst is S. R. Oates (samantha.oates AT ucl.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130420B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14412
SUBJECT: GRB 130420B: MASTER-Net optical observations
DATE:    13/04/20 13:51:33 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, 
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko,  A.Sankovich
Sternberg Astronomical Institute, Moscow State University

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Blagoveschensk was pointed to the  GRB130420B (Oates et. al 
GCN 14411)  44 sec s after notice time and 63 sec after GRB time at 
2013-04-20 12:57:34.948 UT in two polarizations. On 
our first (10s exposure) set we haven't found optical transient  within 
SWIFT error-box (ra=12 12 28 dec=+54 23 24 r=0.050000).
The 5-sigma upper limit has been about 16.0 mag.
The message may be cited.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14413
SUBJECT: GRB 130420A: Weihai Optical Observations
DATE:    13/04/20 13:57:41 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), C. Cao, S.M. Hu (SDU) report:

We observed the field of GRB 130420A (Page et al., GCN 14406) using
the 1m telescope located in Weihai, Shandong Province, China.
Observations started at 11:41:32 UT, 2013-04-20 (i.e., 4.218 hr after
the BAT trigger) and 12x180s I-band frames were obtained.

The optical afterglow (Page et al., GCN 14406) is clearly detected in
our stacked image to be of I=19.4 mag, calibrated with nearby USNO B1
stars. It has decayed by about 0.5 mag, compared to the measurement in
Watson et al. (GCN 14409).

We thank Dayong Ren for carrying out these observations.


GRB_name: GRB130420B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14414
SUBJECT: GRB 130420B: Faulkes Telescope North observations
DATE:    13/04/20 14:18:52 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara) and C. G. Mundell  
(Liverpool) report on behalf of a larger collaboration:

The 2-m Faulkes Telescope North (FTN) automatically began observing  
GRB130420B (Oates et al., GCN 14411) on April 20, 12:59:50 UT  
corresponding to ~200 seconds after the burst event.

We detect no new, uncatalogued source in the BAT error circle down to  
the following limiting magnitudes:

Mid time from   Exp    Filter   Mag limit
trigger (min)   (sec)
---------------------------------------------------
28.62           540      R       > 20.5
32.75           520      I        > 20.0
---------------------------------------------------

The magnitudes are calibrated against nearby USNO-B1.0 stars.


GRB_name: GRB130420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14415
SUBJECT: GRB130420A : Xinglong TNT optical upper limit
DATE:    13/04/20 15:59:58 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L.P. Xin, M. Zhai, J. Y. Wei, Y. L. Qiu,  J. Wang, 
J. S. Deng, C. Wu, X.H. Han  report on behalf of EAFON team:

We began to observe the field of GRB 130420A  (Page et al., GCN 14406 )
using  80cm TNT telescope located at Xinglong observatory, China
at 12:16:56 UT on 2013-04-20. We obtained 12x300s R-band images in a
poor seeing and cloudy weather, with a median time of 5.3 hr after the BAT trigger.

The afterglow reported (Page et a., GCN 14406 ) is not detected in the stacked image, 
down to a 3 sigma limit of R~18.0 mag, calibrated with USNO B2 stars.

This message may be cited.


GRB_name: GRB130420A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14416
SUBJECT: GRB 130420A: Enhanced Swift-XRT position
DATE:    13/04/20 17:34:00 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2151 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 130420A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 196.10626, +59.42406 which is equivalent
to:

RA (J2000): 13h 04m 25.50s
Dec (J2000): +59d 25' 26.6"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130418A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14417
SUBJECT: Konus-Wind observation of GRB 130418A
DATE:    13/04/20 17:42:33 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long GRB 130418A (Swift-BAT trigger #553847:
De Pasquale et al., GCN 14377; Cummings et al., GCN 14392)
was observed by Konus-Wind (K-W) in the waiting mode.

K-W light curve shows a soft pulse started ~215 s before
the BAT trigger (T0(BAT)=19:00:53).
A total duration of the pulse is ~120 s.
The decay phase of the burst which had triggered Swift-BAT
is virtually indistinguishable from the K-W background.
Since the K-W ecliptic latitude response to the burst
is consistent with the BAT localization, we suggest
the pulse observed by K-W is an initial phase of GRB 130418A.

As observed by Konus-Wind, this part of the burst had
a fluence of (1.57  0.25)x10^-5 erg/cm2 and a 3-s peak flux,
measured from T0(BAT)-186 s, of (2.5  0.4)x10^-7 erg/cm2/s
(both in the 20 - 1200 keV energy range).

Fitting the K-W 3-channel time-averaged spectrum
(from T0(BAT)-215 s to T0(BAT)-95 s) by a simple
power-law model yields a photon index of 2.12  0.09,
which is consistent with the slope reported by BAT
for the burst tail.

Assuming z=1.218 (de Ugarte Postigo et al., GCN 14380;
Kruehler et al. GCN 14390) and a standard cosmology model
with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73,
the isotropic energy release E_iso is (6.3  1.0)x10^52 erg,
and the peak luminosity (L_iso)_max is (1.2  0.2)x10^51 erg/s.

All the quoted errors are estimated at the 1 sigma confidence level.

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB130418A/


GRB_name: GRB130420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14418
SUBJECT: GRB 130420A: GMG optical observation
DATE:    13/04/20 18:49:21 GMT
FROM:    Xiao-hong Zhao at Yunnan Obs  <zhaoxiaohong78@gmail.com>

X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J.-M. Bai 
(YNAO) report on behalf of a larger collaboration:

We observed the field of GRB 130420A (Page et al., GCN 14406) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations
started at 13:36:00 UT on 2013-04-20 (i.e., 6.13 hrs after the burst, ~2 hrs later than the observation of Xu et al., GCN 14413) and 3x600s R-band and 1x600s I-band images were obtained. The optical counterpart of this burst was detected in both bands. The mag are R~19.4 and I~20.2 calibrated with USNO B1 stars. 
   
We thank the GMG staff, especially Yu-Xin Xin, Gui-Hua He and Jian-Duo He for
performing these observations.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14419
SUBJECT: GRB 130420A, Swift-BAT refined analysis
DATE:    13/04/20 19:33:42 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

GRB 130420A, Swift-BAT refined analysis
  
A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), M. J. Page (UCL-MSSL),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
  
Using the data set from T-239 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130420A (trigger #553977)
(Page et al., GCN 14406).  The BAT ground-calculated position is
RA, Dec = 196.118, 59.421 deg which is
    RA(J2000)  =  13h 04m 28.3s
    Dec(J2000) = +59d 25' 16.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.
  
The mask-weighted light curve shows a precursor beginning gradually at about
T-20 seconds and increasing irregularly to about T+100 seconds.  The main
emission had a FRED shape peaking at about T+110 seconds that was detectable
until about T+200 seconds.  T90 (15-350 keV) is 123.5 +- 13.1 sec (estimated
error including systematics).
  
The time-averaged spectrum from T-19.7 to T+189.9 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.52 +- 0.25,
and Epeak of 33.2 +- 6.8 keV (chi squared 42.40 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 7.1 +- 0.3 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+110.67 sec in the 15-150 keV band is
3.4 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.18 +- 0.05 (chi squared 66.06 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/553977/BA/


GRB_name: GRB130420B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14420
SUBJECT: GRB 130420B, Swift-BAT refined analysis
DATE:    13/04/20 19:35:22 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), S. R. Oates (UCL-MSSL),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
  
Using the data set from T-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130420B (trigger #553996)
(Oates et al., GCN 14411).  The BAT ground-calculated position is
RA, Dec = 183.095, 54.376 deg which is
    RA(J2000)  =  12h 12m 22.7s
    Dec(J2000) = +54d 22' 33.2"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
  
The mask-weighted light curve shows a single gradual peak beginning at about
T-5 seconds and detectable to T+12 seconds.  T90 (15-350 keV) is 10.2 +- 5.4 sec
(estimated error including systematics).
  
The time-averaged spectrum from T-1.0 to T+16.0 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.28 +- 0.52,
and Epeak of 71.3 +- 14.0 keV (chi squared 42.36 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.0 +- 0.5 x 10^-07 erg/cm2
and the 1-sec peak flux measured from T+0.91 sec in the 15-150 keV band is
1.4 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.45 +- 0.10 (chi squared 61.94 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/553996/BA/


GRB_name: GRB130420B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14421
SUBJECT: GRB 130420B: Enhanced Swift-XRT position
DATE:    13/04/20 19:47:34 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page, P.A. Evans and M.R. Goad (U. Leicester) report
on behalf of the Swift-XRT team:

Using 1436 s of XRT Photon Counting mode data and 3 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
183.12805, 54.39054 which is equivalent to:

RA (J2000):  12 12 30.73
Dec (J2000): +54 23 25.9

with an uncertainty of 2.0 arcsec (radius, 90% confidence).

This position may be improved as more data are received.  The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130420A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14422
SUBJECT: GRB 130420A: Swift-XRT refined Analysis
DATE:    13/04/20 19:50:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Maselli  (INAF-IASFPA), V. Mangano (INAF-IASFPA), M.C. Stroh (PSU),
D.N. Burrows (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), B.P.
Gompertz (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri
(INAF-OAB) and M.J. Page report on behalf of the Swift-XRT team:

We have analysed 7.9 ks of XRT data for GRB 130420A (Page  et al. GCN
Circ. 14406),  from 742 s to 19.7 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN. Circ 14416).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.81 (+/-0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.29 (+0.14, -0.13). The
best-fitting absorption column is  7.1 (+2.5, -2.4) x 10^20 cm^-2, in
excess of the Galactic value of 1.3 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.1 x 10^-11 (4.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.1 (+2.5, -2.4) x 10^20 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:      2.29 (+0.14, -0.13)

If the light curve continues to decay with a power-law decay index of
0.81, the count rate at T+24 hours will be 0.021 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.5 x
10^-13 (8.5 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00553977.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130420B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14423
SUBJECT: GRB130420B: GMG optical upper limit
DATE:    13/04/20 20:23:53 GMT
FROM:    Xiao-hong Zhao at Yunnan Obs  <zhaoxiaohong78@gmail.com>

X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J.-M. Bai
(YNAO) report on behalf of a larger collaboration:

We observed the field of GRB 130420B (Page et al., GCN 14421; Oates et al., GCN 14411) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations
started at 13:21:14 UT on 2013-04-20 (i.e., 0.4 hrs after the burst). The observations lasted for ~10min. The afterglow was not found at
the XRT position, down to a upper limit of R>22.6.

We thank the GMG staff, especially Yu-Xin Xin, Gui-Hua He and Jian-Duo He for
performing these observations.

[GCN OPS NOTE(20apr13):  I hav removed their copy-paste double TITLE block.]


GRB_name: GRB130420A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14424
SUBJECT: GRB 130420A: Swift/UVOT Detection
DATE:    13/04/20 21:06:26 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates, M. De Pasquale, and M. J. Page (UCL-MSSL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130420A
739 s after the BAT trigger (Page et al., GCN Circ. 14406).
A source consistent with the XRT position
(Goad et al. GCN Circ. 14416) is detected in the initial UVOT exposures.
The GRB is detected in all filters and is therefore consistent with
being at a redshift of  ~<1.6.

The preliminary UVOT position is:
  RA  (J2000) =  13:04:25.55 = 196.10647 (deg.)
  Dec (J2000) = +59:25:27.1  =  59.42420 (deg.)
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              739          888          147         17.14 +/- 0.03
v                 1072         1092           20         17.66 +/- 0.31
b                 1171         1191           19         18.13 +/- 0.21
u                 1146         1166           20         17.19 +/- 0.17
w1                1122         1141           19         17.51 +/- 0.29
m2                1097         1465           58         18.30 +/- 0.31
w2                1049         1240           39         18.50 +/- 0.33

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB130420B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14425
SUBJECT: GRB 130420B: Swift/UVOT Upper Limits
DATE:    13/04/20 21:28:15 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <m.depasquale@ucl.ac.uk>

M. De Pasquale, S. R. Oates (MSSL-UCL) reports on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130420B
57 s after the BAT trigger (Oates et al., GCN Circ. 14411).
No optical afterglow consistent with the XRT position (Page et al., GCN
circ.
14421) is detected in the initial and summed UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag


white               57         5841          460         >21.7
v                 4707         4907          197         >19.6
b                 4091         5727          393         >20.9
u                 3886         5521          393         >20.6
w1                5117         5317          197         >20.1
m2                4912         5111          197         >19.8
w2                4502         4702          197         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB130420B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14426
SUBJECT: GRB 130420B: Weihai optical upper limit
DATE:    13/04/20 22:06:40 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

Dong Xu (DARK/NBI), Chen Cao, Shaoming Hu, Dayong Ren (SDU) report:

We observed the field of GRB 130420B (Oates et al., GCN 14411) using
the 1m telescope located in Weihai, Shandong Province, China. We
obtained 12x300s I-band frames with a mean time of 2.973 hr after the
BAT trigger.

No optical source is detected within the enhanced XRT error circle
(Page et al., GCN 14421) in the stacked image, down to a limiting
magnitude of I>21.2 mag.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14427
SUBJECT: Skynet/GORT observations of GRB130420A
DATE:    13/04/20 22:28:05 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/NC AnTPROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, N. Frank, A. LaCluyze, D. Reichart, K. McLin,  L. Cominsky,
T. Berger, J. A. Crain, H. T. Cromartie,  R. Egger, A. Foster, J.
Haislip, K. Ivarsen, M. Maples, J. Moore,   M. Nysewander, and E.
Speckhard report:

Skynet observed the Swift/BAT localization of GRB 130420A (Page et al.,
GCN 14406, Swift trigger 553977) with the 14" GLAST Optical Robotic
Telescope (GORT) at the Hume observatory in California, beginning ~100s
after the trigger in RcIc, and continuing until the source set at
t=4.9h. We detect the afterglow reported by Guidorzi et al. (GCN 14405)
at RA 13:04:06.6, Dec +59:25:25.2 (J2000), within the error circle
reported by the Swift XRT (GCN 14406). Photometry was calibrated to six
SDSS stars in the field.
The afterglow exhibits a rising light curve in both Rc and Ic bands at
early times, peaking at t=330s (peak Rc~16, Ic~15.5), after which it
fades with an approximate temporal index alpha~-1.  There is some
evidence for flattening of the Ic-band light curve at t>1h, at which
time Ic~18.7.

Follow-up observations at GORT have been scheduled.

A preliminary light curve of the first night's data can be found at:
http://skynet.unc.edu/grb/grb130420a.png


GRB_name: GRB130420A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14428
SUBJECT: GRB 130420A: ISON-NM optical observations
DATE:    13/04/21 03:58:45 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

L. Elenin (KIAM),  A. Volnova ( IKI),  V. Savanevych (KNURE),   A. 
Bryukhovetskiy (NSFCTC),  I. Molotov (KIAM), A. Pozanenko (IKI) report on 
behalf of  larger GRB  follow-up collaboration:

We observed the field of  the Swift GRB 130420A (Page et al., GCN 14406) 
with 0.45-m telescope of ISON-NM observatory  on Apr. 20,  between (UT) 
07:30:54 - 10:51:49.  The observation started automatically 144 s after 
burst trigger. We took  several unfiltered images of  30, 60 and 300 s 
exposures.  The optical counterpart of GRB 130418A (Guidorzi et al., GCN 
14405; Page et al., GCN 14406; Guver et al., GCN 14407) is clearly visible 
in single images.

Coordinates of the counterpart are (J2000) RA = 13:04:25.56 Dec = 
+59:25:26.8 with uncertainties of 0.2" coincide with the coordinates 
reported early  (Guidorzi et al., GCN 14405, Guver et al., GCN 14407).

A photometry of single and later combined  image is based  on the SDSS stars 
with assumed R-magnitude
J130421.49+592547.6 R = 16.13
J130416.49+592509.2 R = 16.95
J130443.88+592659.3 R = 14.54

Preliminary light curve can be found at 
http://grb.rssi.ru/GRB130420A/GRB130420A_lightcurve_ISON-NM.png
The light curve is clearly exhibit a fast rise and peaked with 16.1 mag at 
~0.0207days after burst trigger following steep power law decay and later at 
0.05 days swallowing to the typical afterglow power law. 


GRB_name: GRB130420A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14429
SUBJECT: GRB 130420A: Fermi GBM observation
DATE:    13/04/21 04:44:55 GMT
FROM:    Shaolin Xiong at UAH  <sx0002@uah.edu>

Shaolin Xiong (UAH) and Arne Rau (MPE)
report on behalf of the Fermi GBM Team:

"At 07:30:19.92 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130420A (trigger 388135822 / 130420313),
which was also detected by the Swift (Page et al. 2013, GCN 14406).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 134 degrees.

The GBM light curve consists of precursors and a bright peak
with a duration (T90) of about 102 s (50-300 keV).
The time-averaged spectrum from T0-10 s to T0+27 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is 1.00 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 56 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.0 s in the 10-1000 keV band
is 5.2 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130420B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14430
SUBJECT: GRB 130420B: Swift-XRT refined Analysis
DATE:    13/04/21 05:10:08 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of
the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 130420B (Oates  et al. GCN
Circ. 14411),  from 39 s to 39.9 ks after the  BAT trigger. The data
comprise 18 s in Windowed Timing (WT) mode (the first 8 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. Using 2638 s of PC mode data and 4 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 183.12838, +54.39054
which is equivalent to:

RA (J2000): 12h 12m 30.81s
Dec(J2000): +54d 23' 26.0"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.11 (+0.09, -0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.0 (+/-0.4). The
best-fitting absorption column is  6.8 (+9.6, -5.4) x 10^20 cm^-2,
consistent with the Galactic value of 1.4 x 10^20 cm^-2 (Kalberla et
al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.5 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column:      6.8 (+9.6, -5.4) x 10^20 cm^-2
Galactic foreground: 1.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.0 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
1.11, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.1 x
10^-14 (8.5 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00553996.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14431
SUBJECT: GRB 130420A: Continued RATIR Optical and NIR Observations
DATE:    13/04/21 16:54:47 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:

We again observed the field of GRB 130420A (Page et al., GCN 14406) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 21.30 to 2013/04 21.47UTC (23.66 to 27.79 hours after the BAT trigger), obtaining a total of 1.44 hours exposure in the r' and i' bands and 0.59 hours exposure in the Z, Y, J, and H bands.

The afterglow is well-detected.  In comparison with SDSS DR8 and 2MASS, we obtain:

 r'   22.11 +/- 0.08
 i'   21.90 +/- 0.09
 Z   21.52 +/- 0.18
 Y   21.40 +/- 0.31
 J   21.24 +/- 0.26
 H   20.38 +/- 0.23

These magnitudes are in the AB system, quoted with 1-sigma uncertainty, and not corrected for Galactic extinction in the direction of the GRB.  In comparison with our observations on the previous night (Watson et al., GCN 14409), the afterglow has faded by more than about 2 magnitudes in all bands.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.


GRB_name: GRB130420B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14432
SUBJECT: GRB 130420B: RATIR Optical and NIR Observations
DATE:    13/04/21 17:24:52 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130420B (Oates et al., GCN 14411) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/04 21.15 to 2013/04 21.29 UTC (14.54 to
18.10 hours after the BAT trigger), obtaining a total of 1.32 hours
exposure in the r' and i' bands and 0.55 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Page et al., GCN 14430), in
comparison with SDSS DR8 and 2MASS, we obtain the following upper limits
(3-sigma) in the AB magnitude system:

 r'> 23.19
 i'> 22.99
 Z > 21.87
 Y > 21.39
 J > 21.20
 H > 20.53

These magnitudes are not corrected for Galactic extinction in the direction
of the GRB.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14434
SUBJECT: GRB 130418A: WSRT radio observation
DATE:    13/04/22 06:50:13 GMT
FROM:    Alexander van der Horst at U of Amsterdam  <A.J.vanderHorst@uva.nl>

A.J. van der Horst (University of Amsterdam) reports on behalf
of a large collaboration:

"We observed the position of the GRB 130418A afterglow at 4.9 GHz with
the Westerbork Synthesis Radio Telescope at April 21 13.53 UT to
April 22 01.49 UT, i.e. 2.77 - 3.27 days after the burst (GCN 14377).
We do not detect a radio source at the position of the optical
counterpart (GCN 14384). The three-sigma rms noise in the map around
that position is 69 microJy per beam. The formal flux measurement for
a point source at the position of the optical counterpart is 34 +/- 23 
microJy.

We would like to thank the WSRT staff for quickly scheduling and
obtaining these observations."


GRB_name: GRB130420B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14435
SUBJECT: GRB 130420B: Fermi GBM observation
DATE:    13/04/22 11:29:13 GMT
FROM:    Arne Rau at MPE  <arau@mpe.mpg.de>

Arne Rau (MPE) reports on behalf of the Fermi GBM Team:

"At 12:56:32.99 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130420B (trigger 388155395 / 130420539),
which was also detected by Swift/BAT (Oates et al., GCN 14411).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is about 50 degrees.

The GBM light curve shows a single pulse with a duration (T90) of
about 16 s (50-300 keV). The time-averaged spectrum from T0-4 s
to T0+4 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is 0.24 +/- 0.25 and
the cutoff energy, parameterized as Epeak, is 91 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(1.04 +/- 0.08)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 2.6 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14436
SUBJECT: GRB 130420A: Early RAPTOR Simultaneous Multi-Color Observations
DATE:    13/04/22 17:34:49 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:

The RAPTOR network of robotic optical telescopes made follow-up observations
of Swift trigger 553977 (Page, et al., GCN 14406).  Our RAPTOR-S and RAPTOR-T
robotic telescopes located in Los Alamos, NM, began imaging at 07:29:52.95 UTC,
83.4 s after the Swift BAT trigger and continued during the entire period the
BAT was detecting the dominant gamma-ray pulse (Lien, et al., GCN 14419).  We
detect optical emission during the gamma-ray emitting interval at the location
of the counterpart reported by the Faulkes team (Guidorzi, et al., GCN 14405).
In subsequent images we see a rapid rise in brightness at the same location,
peaking at about T+300s.  These observations were made simultaneously using
SDSS g', r', i', z' and clear filters.  Our unfiltered observations are
consistent with the lightcurve published by the ISON team (Elenin, et al.,
GCN 14428).


GRB_name: GRB130420A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14437
SUBJECT: GRB 130420A: Redshift from 10.4m GTC
DATE:    13/04/22 18:33:44 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), N. Tanvir (U. Leicester), 
R. Sanchez-Ramirez (IAA-CSIC), C.C. Thoene (IAA-CSIC), 
J. Gorosabel (UPV/EHU, IAA-CSIC), and J. P. U. Fynbo (DARK/NBI) report:

We obtained spectroscopy of the afterglow of GRB 130420A (Page 
et al. GCN 14406) with the 10.4m GTC telescope on the 22nd April 2013,
starting at 03:42 UT (1.84 days after the burst). The observation consisted of 
4x900 s using the R500B grating, with a resolution of R~500 in the range 3600 
- 8700 A.

The spectrum shows an emission line that we identify as [OII] from the host 
and several absorption features that correspond to MgII, MgI, FeII and AlIII at
a common redshift of 1.297, which we identify as the redshift of the GRB.

We also note the presence of an unrelated nearby galaxy (at an angular 
separation of 2.5") which shows emission lines of [OII], H-beta and [OIII] at a 
redshift of 0.584.

We acknowledge the excellent support of the GTC staff.


GRB_name: GRB130418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14438
SUBJECT: GRB 130418A: Continued RATIR Optical and NIR Observations
DATE:    13/04/22 21:17:15 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130418A (de Pasquale et al., GCN 14377) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional
on Sierra San Pedro Mrtir from 2013/04 22.14 to 2013/04 22.33 UTC (80.35
to 84.95 hours after the BAT trigger), obtaining a total of 2.84 hours
exposure in the r' and i' bands and 1.19 hours exposure in the Z, Y, J, and
H bands.


At the position of the transient observed on 2013/04/19 (GCN 14388) and
2013/04/20 (GCN 14404), in comparison with SDSS DR8 and 2MASS, we obtain
the following upper limits (3-sigma) in the AB magnitude system:

 r'> 23.12
 i'> 22.93
 Z > 22.52
 Y > 21.89
 J > 21.85
 H > 21.25

These magnitudes are not corrected for Galactic extinction in the direction
of the GRB.  The source is thus more than about 1 magnitude fainter than it
was observed to be two days ago.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130420A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14439
SUBJECT: GRB 130420A: Continued RATIR Optical and NIR Observations
DATE:    13/04/22 21:22:43 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We again observed the field of GRB 130420A (Page et al., GCN Circular
14406) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 22.35 to
2013/04 22.47 UTC (48.84 to 51.69 hours after the BAT trigger),
obtaining a total of 0.71 hours exposure in the r' and i' bands and 0.29
hours exposure in the Z, Y, J, and H bands.

The afterglow is again detected in several bands.  In comparison with
SDSS DR8 and 2MASS, we obtain:

r' 22.63 +/- 0.17
i' 22.46 +/- 0.17
Z  21.62 +/- 0.25
Y > 21.32
J > 21.39
H > 20.91

These magnitudes are in the AB system, quoted with 1-sigma uncertainty,
and not corrected for Galactic extinction in the direction of the GRB. 
The upper limits are at the 3-sigma level.

In comparison with our earlier observations (Watson et al., GCN Circular
14409; Butler et al., GCN Circular 14431), we see that the afterglow
faded by about 2 magnitudes from about 3 to about 25 hours after the
Swift trigger, but then by only about another 0.5 magnitudes from about
25 to about 50 hours after the Swift trigger.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130420A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14440
SUBJECT: GRB 130420A: ROTSE-III data analysis
DATE:    13/04/24 21:13:55 GMT
FROM:    Farley V. Ferrante at Southern Methodist U/ROTSE  <fferrante@smu.edu>

F. V. Ferrante (SMU), G. Dhungana (SMU), T. Guver (Sabanci U), W. Zheng (UC Berkeley), H. Flewelling (IfA/Hawaii), F. Yuan (Australian National University), and R. Kehoe (SMU) report on behalf of the ROTSE collaboration:

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 130420A (Swift trigger 553977; Guidorzi et al., GCN 14405; Page et al., GCN 14406; Guver et al., GCN 14407). The first image was at 07:29:51.5 UT, 82.0 s after the burst (7.5 s after the GCN notice time). We continued to monitor the source reported in GCN 14405, 14406, and 14407. The unfiltered images are calibrated relative to USNO A2.0. We took 220 20-sec exposures and observed a maximum magnitude of 15.5.

Further analysis of ROTSE-IIIb data using RPHOT indicates that the afterglow of GRB 130420A displays a single power-law decay with index alpha = - 0.70 up to ~1500 s after the burst. After the power law fall-off, the afterglow continued to be detected in subsequent images for ~6 ks. The minimum observed magnitude was 17.5.


GRB_name: GRB130420A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14441
SUBJECT: GRB 130420A: Continued RATIR Optical and NIR Observations
DATE:    13/04/25 01:25:12 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We again observed the field of GRB 130420A (Page et al., GCN Circular
14406) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 24.26 to
2013/04 24.46 UTC (94.73 to 99.64 hours after the BAT trigger),
obtaining a total of 2.84 hours exposure in the r' and i' bands and 1.19
hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with SDSS
DR8 and 2MASS, we obtain the following upper limits (3-sigma) in the AB
magnitude system:

r' > 23.15
i' > 23.02
Z > 21.75
Y > 21.44
J > 21.72
H > 21.16

These magnitudes are not corrected for Galactic extinction in the
direction of the GRB.

In comparison with our earlier observations (Watson et al., GCN Circular
14409; Butler et al., GCN Circular 14431; Watson et al., GCN Circular
14439), the source has faded by about at least a magnitude in r' and i'
between about 50 and about 97 hours.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130425A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14442
SUBJECT: GRB 130425A: Fermi GBM detection
DATE:    13/04/25 15:24:49 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 07:51:16.23 UT on 25 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130425A (trigger 388569079 / 130425327).

The on-ground calculated location, using the GBM trigger data, 
is RA = 19.0, DEC = -72.2 (J2000 degrees, equivalent 
to 01 h 16 m, -72 d 12 '), with an uncertainty of 2.9 degrees 
(radius, 1-sigma containment, statistical only; there is additionally 
a systematic error which is currently estimated to be 2 to 3 degrees).

The angle from the Fermi LAT boresight is 150 degrees.

The GBM light curve shows two peaks  with a duration (T90) 
of about 66 s (50-300 keV). The time-averaged spectrum from 
T0-2.880 s to T0+69.825 s is best fit by a power law function 
with an exponential high-energy cutoff.  The power law index
 is -1.28 +/- 0.03  and the cutoff energy, parameterized as Epeak, is 254
(+14/-13) keV.

The event fluence (10-1000 keV) in this time interval is
(5.2 +/- 0.1)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+43.5207 s in the 10-1000 keV band
is 21.8 +/- 1.1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130420B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14444
SUBJECT: GRB 130420B:  CARMA and VLA radio observations
DATE:    13/04/25 20:44:52 GMT
FROM:    Ashley Zauderer at CfA  <bevinashley@gmail.com>

B. A. Zauderer and E. Berger (Harvard) report on behalf of the
CARMA Key Project "A Millimeter View of the Transient Universe"
and a larger collaboration:

"We observed the position of GRB 130420B (Oates et al.; GCN 14411) 
beginning 2013 Apr 23.29 UT (dt = 2.75 d) with the Very Large Array 
(VLA) and beginning 2013 Apr 22.91 (dt = 2.37 d) with the Combined Array 
for Research at Millimeter Astronomy (CARMA).  We do not find any 
significant radio emission at the position of the enhanced Swift-XRT 
position (Page et al.; GCN 14421) at a mean frequency of 5.8 GHz (VLA) 
to a 3-sigma limit of 32 uJy, at 21.8 GHz (VLA) to a 3-sigma limit of 47 
uJy, or at 85 GHz (CARMA) to a 3-sigma limit of 0.78 mJy.

We thank the VLA and CARMA observatories for their support of these 
observations."


GRB_name: GRB130420A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14445
SUBJECT: GRB 130420A: Continued Skynet/GORT Observations/Detections
DATE:    13/04/25 22:19:25 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, N. Frank, A. LaCluyze, D. Reichart, K. McLin, L. Cominsky, 
T. Berger, H. T. Cromartie, R. Egger, A. Foster, J. Haislip, K. Ivarsen, 
M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:

Skynet continued observing the field of GRB 130420A (Page et al., GCN 
14406, Swift trigger #553977) with the 14" GLAST Optical Robotic 
Telescope (GORT) at the Hume Observatory in California. It took 214 80-s 
exposures in Ic at times t=20.48-23.30h and t=26.25-28.56h after burst 
trigger, and 96 80-s exposures in Rc at t=23.33-26.15h. We performed 
photometry on the stacked exposures in each band, calibrated to six SDSS 
stars in the field. We detect the afterglow in both Ic and Rc bands at 
t~24h:

band   exp length   mean time since trig   mag(Vega)
Ic     4.76h        24.37h                 21.04 (+0.43,-0.31)
Rc     2.47h        24.77h                 21.00 (+0.25,-0.21)

As we note in Trotter et al. (GCN 14427), and as Elenin et al. (GCN 
14428) confirm, the afterglow exhibits a rising light curve at early 
times, peaking at t=330s (peak Rc~16, Ic~15.5). After the peak, the 
light curve fades with a power law index alpha~-0.9.

A preliminary light curve of the first and second nights' data is at: 
http://skynet.unc.edu/grb/grb130420a_2.png


GRB_name: GRB130425A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14446
SUBJECT: IPN Triangulation of GRB 130425A
DATE:    13/04/26 16:07:26 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

K. Hurley, and J. Goldsten, on behalf of the MESSENGER GRNS GRB team,

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima, on behalf of the Suzaku WAM
team, report:

The long-duration, intense GRB 130425A (Fermi/GBM detection: von 
Kienlin, GCN Circ. 14442) has been observed by Konus-Wind, MESSENGER 
(GRNS), INTEGRAL (SPI-ACS), and Suzaku (WAM), so far, at about 28280 s 
UT (07:51:20).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
---------------------------------------------
  Center:
     6.211 (00h 24m 51s) -70.183 (-70d 11' 00")
  Corners:
    14.165 (00h 56m 40s) -70.601 (-70d 36' 05")
    11.987 (00h 47m 57s) -70.402 (-70d 24' 09")
   358.255 (23h 53m 01s) -69.341 (-69d 20' 28")
     0.370 (00h 01m 29s) -69.740 (-69d 44' 24")
---------------------------------------------
The error box area is 0.683 sq. deg, and its maximum
dimension is 5.58 deg (the minimum one is 45 arcmin).

This box may be improved.

The center of the GBM location (von Kienlin, GCN Circ. 14442) is 4.6
deg from the center of the IPN box.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB130425_T28280/IPN/


GRB_name: GRB130425A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14447
SUBJECT: Konus-Wind observation of GRB 130425A
DATE:    13/04/26 16:17:46 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration intense GRB 130425A
(Fermi-GBM detection: von Kienlin, GCN 14442;
IPN triangulation: Hurley et al., GCN 14446)
triggered Konus-Wind at T0=28280.029s UT (07:51:20.029)

The light curve shows an initial pulse, from ~T0-9 s to
~T0+15 s, followed by a bright multi-peaked structure
from ~T0+30 s to ~T0+68 s.
A total duration of the burst is ~80 s.
The emission is seen up to 10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130425_T28280/

As observed by Konus-Wind, the burst
had a fluence of (5.9  0.7)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+39.808s,
of (7.1  0.6)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+73.216 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.29  0.08,
the high energy photon index beta = -2.46  0.23,
the peak energy Ep = 167  17 keV,
chi2 = 107/97 dof.

The spectrum at the maximum count rate (measured from T0+33.024
to T0+40.448 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.10  0.12,
the high energy photon index beta = -2.40  0.36,
the peak energy Ep = 237  45 keV,
chi2 = 91/97 dof.

All the quoted results are preliminary.


GRB_name: GRB130427A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14448
SUBJECT: GRB 130427A: Swift detection of a very bright burst with a likely bright optical counterpart
DATE:    13/04/27 08:24:13 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Maselli (INAF-IASFPA), A. P. Beardmore (U Leicester),
A. Y. Lien (NASA/GSFC/ORAU), V. Mangano (INAF-IASFPA),
C. J. Mountford (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 07:47:57 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130427A (trigger=554620).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 173.139, +27.692 which is 
   RA(J2000) = 11h 32m 33s
   Dec(J2000) = +27d 41' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows an extremely bright
complex peak about 20 seconds long starting at T-50, while Swift was 
slewing from the previous pre-planned target, followed by a smaller 
peak during the slew to the burst with emission through at least T+200. 
The peak count rate was ~ 100,000 counts/sec (15-350 keV), 
at T-40 sec, before the trigger. 

The XRT began observing the field at 07:50:17.7 UT, 140.2 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 173.1362, 27.7129 which is equivalent to:
   RA(J2000)  = +11h 32m 32.69s
   Dec(J2000) = +27d 42' 46.4"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 75 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 147 seconds after the BAT trigger.  A blurred bright source
appears to be located near the XRT position in the initial 2.7'x2.7'
sub-image.  However, the lack of reference stars and lack of star tracker
lock prevents a definitive identification and the measurement of a position
or magnitude. 

This is an extremely bright burst in all three instruments,
and it was also seen by Fermi/GBM. 

After the slew to the burst, the star trackers had trouble
locking on to give a spacecraft attitude, so the XRT position
may be inaccurate at the arcminute level. 

The apparent optical counterpart appears extremely blurred, 
possibly due to the lack of star tracker lock, but more likely to be 
due to instrumental effects on a very bright optical counterpart. 


Further follow-up is warranted for all ground-based observatories. 

Burst Advocate for this burst is A. Maselli (maselli AT ifc.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14449
SUBJECT: GRB 130427A: P60 early nondetection
DATE:    13/04/27 08:39:09 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration:

The Palomar 60-inch telescope automatically responded to GRB 130427A 
(Maselli et al., GCN 14448) and began taking observations at 07:52:22 UT 
(4.42 minutes after the BAT trigger).  A series of 60-second images were 
taken in r, i, and z filters; observations are still ongoing. Inspection 
of individual frames shows no detection of an optical transient 
consistent with the XRT position to approximately r > 20.6 mag, i > 20.7 
mag, z > 19.7 mag.

Nondetection of an afterglow in rapidly-triggered P60 observations is 
unusual (Cenko et al. 2009, ApJ 693, 1484), especially in the presence 
of an very bright GRB and early XRT afterglow.  This is suggestive of a 
highly extinguished (or possibly high-redshift) burst, and may indicate 
that the possible UVOT source reported by Maselli et al. was spurious. 
Further observations, especially in the NIR, are strongly encouraged.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14450
SUBJECT: GRB 130427A: early optical observations
DATE:    13/04/27 08:46:41 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

L. Elenin (KIAM),  A. Volnova ( IKI),  V. Savanevych (KNURE),   A. 
Bryukhovetskiy (NSFCTC),  I. Molotov (KIAM), A. Pozanenko (IKI) report on
behalf of  larger GRB  follow-up collaboration:

We started observation of  the field of  the Swift GRB 130427A (Maselli et 
al., GCN 14448)  with 0.45-m telescope of ISON-NM observatory on Apr. 27 
(UT)   07:50:17.
On the first images of 30 s exposure we identified very bright optical 
counterpart of GRB 130427A (Maselli et al., GCN 14448) at about 12m in the 
intitial images.

The coordinates of the counterpart are (J2000) 11 32 32.84 +27 41 56.2 with 
uncertainties of about 1".

Observations are continuing.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14451
SUBJECT: GRB 130427A: P60 early detection
DATE:    13/04/27 08:56:29 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration:

Upon further inspection of the P60 images, we identify a very bright 
optical source separated by about 51 arcseconds from the XRT afterglow 
location but consistent with the optical afterglow location reported by 
Elenin et al. (GCN 14450)   The source is saturated in the early images. 
  Further observations are ongoing.

We also note that there is an SDSS galaxy at this position, suggesting a 
low-redshift event.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14452
SUBJECT: GRB 130427A: Faulkes Telescope North detection
DATE:    13/04/27 09:21:48 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara), A. Gomboc,
J. Japelj (U. Ljubljana), C.G. Mundell (LJMU) report on
behalf of a larger collaboration:

The 2-m Faulkes Telescope North robotically followed up GRB130427A
(SWIFT trigger 554620,  Maselli et al. GCN 14448 ) starting 4.3 min
after the GRB trigger time. We detect a bright fading source
at the position reported by Elenin et al. (GCN 14450), Perley
(GCN 14451) with R ~11.5 mag.

We note also a faint, 21-mag, underlying source visible in SDSS
images that may suggest this GRB is nearby with a bright host galaxy.

Observations are ongoing.


GRB_name: GRB130427A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14453
SUBJECT: GRB 130427A: PAIRITEL NIR Detections
DATE:    13/04/27 09:47:41 GMT
FROM:    Adam Morgan at U.C. Berkeley  <qmorgan@gmail.com>

A. N. Morgan (UC Berkeley) reports:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) with the
1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at
2013-Apr-27 07h59m24s UT, 11.45 minutes after the Swift Trigger.  In
preliminary mosaics (consisting of 75 ~8 second images for a total
effective exposure time of 9.75 minutes) taken simultaneously in the J, H,
and Ks filters, we detect the optical afterglow (Elenin et al., GCN 14450;
Perley, GCN 14451; Melandri et al., GCN 14452).

The preliminary photometry yields:

post burst
t_mid (hr) exp.(m)   filt  mag   m_err
0.36       9.75      J     12.13  0.03
0.36       9.75      H     11.75  0.04
0.36       9.75      Ks    11.02  0.08

Observations continued until the source passed beyond telescope limits. All
magnitudes are given in the Vega system, calibrated to 2MASS. No correction
for Galactic extinction has been made to the above reported values.


GRB_name: GRB130427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14454
SUBJECT: GRB 130427A: MITSuME Akeno Optical observation(T0+8000s~)
DATE:    13/04/27 11:19:18 GMT
FROM:    Yoichi Yatsu at Tokyo Tech.  <yatsu@hp.phys.titech.ac.jp>

Y. Yatsu, Y. Yano,  R. Usui, Y. Tachibana, K. Ito, T. Yoshii,
S. Kurita, Y. Saito, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed GRB 130427A (Maselli et al., GCNC 14448) with an
optical tri-color (g, Rc, and Ic)  camera attached to the MITSuME
50 cm telescope of Akeno Observatory, Yamanashi, Japan.

The observation started on 2013-04-27 10:06:09.60 UT (8293 sec after the
trigger).
And we found the optical counterpart reported in the twilight sky.
The measured magnitudes were listed below.

MID-MJD  T-EXP[sec]         g'                 Rc                Ic
-------------------------------------------------------------------------------------------
 56409.4231929  360  15.66+/-0.10  15.03+/-0.07  14.71+/-0.09
-------------------------------------------------------------------------------------------
T-EXP: Total Exposure time [sec]
(The photon flux were calibrated against GSC2.3 catalog.)


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14455
SUBJECT: GRB 130427A: Gemini-North redshift
DATE:    13/04/27 11:43:31 GMT
FROM:    Andrew Levan at U.of Leicester  <A.J.Levan@warwick.ac.uk>

A.J. Levan (U. Warwick), S.B. Cenko (U.C. Berkeley), D.A. Perley
(Caltech) and N.R. Tanvir (U. Leicester) report for a larger
collaboration:

We obtained spectroscopy of the afterglow of GRB 130427A (Maselli
et al. GCN 14448, Elenin et al. GCN 14450, Perley et al. GCN 14451)
with Gemini-North / GMOS, begininnig at 09:19 UT roughly 1.5 hours
after the burst. Two different central wavelengths were observed
giving a coverage from ~3100-6700 A. The resulting spectra are of
very high signal to noise given the brightness of the afterglow.
In these spectra we identify absorption lines due to Ca H and K,
Mg I as well as the Mg II doublet at a common redshift of z=0.34.
We suggest this to be the redshift of GRB 130427A.

We do not see evidence for emission lines from an underlying host,
although given the brightness of the afterglow this is not surprising.
The absolute magnitude of object in SDSS, if at z=0.34 is M_R ~
-19.7, relatively bright for a GRB host.

We thank the Gemini-staff for their help in rapidly obtaining these
observations.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14456
SUBJECT: GRB 130427A: Continued P60 follow-up of an extremely bright optical afterglow
DATE:    13/04/27 11:52:44 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>

D. A. Perley (Caltech) and S. B. Cenko (UC Berkeley) report:

We have continued observations of the afterglow of GRB130427A (Maselli et
al., GCN 14448) with the Palomar 60-inch telescope until the field set.
Relative to SDSS reference stars in the field, in some select recent
images we estimate afterglow magnitudes of:

r' = 14.86 mag  (t = 1.40 hours)
r' = 15.32 mag  (t = 2.31 hours)
r' = 15.55 mag  (t = 3.10 hours)

This is brighter (by about 1 mag) than any other Swift burst as measured
at similar epoch (as of 2010; Kann et al. ApJ 720:1513), though still
significantly fainter than GRB 030329 which reached approximately 13 mag
at 0.1 day.  The rate of fading corresponds to a relatively shallow decay
index of approximately alpha~-0.85, suggesting that this afterglow will
remain bright for an extended period.  Worldwide small-telescope follow-up
(including by amateurs) is strongly encouraged.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14457
SUBJECT: GRB 130427A: iTelescope T11 optical observations
DATE:    13/04/27 12:26:03 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:

We have detected GRB 130427A optical afterglow at iTelescope 
observatory T11 (Mayhill, New Mexico) 0.50-m/6.8 astrograph and FLI 
ProLine PL11002M CCD. Three unfiltered and three photometric V filter 
images with 120 sec exposure time were made.

The afterglow was detected at following position RA 11:32:32.83
and DEC +27:41:56.4

The following magnitudes were obtained from the observations using
NOMAD1 1176-0248446 (R=13.520, V=13.120) as the comparison:

Tmid(sec)+T0   Filter         Exp. time    Mag          Mag err. 
4597              unfiltered     120            15.02CR     0.04
4743              unfiltered     120            15.09CR     0.05
4887              unfiltered     120            15.11CR     0.05
5438              V                120            14.89V       0.04
5582              V                120            14.89V       0.04
5726              V                120            14.86V       0.04


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14458
SUBJECT: GRB 130427A: Weihai optical observations
DATE:    13/04/27 13:08:24 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), C. Cao, S.-M. Hu, C.-M. Zhang (SDU) report:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) with
the 1m telescope located in Weihai, Shandong Province, China. A series
of I-, R-, V-, and B-band frames were obtained, and observations are
still ongoing.

Although under quite much cloud, at the afterglow position (Elenin et
al., GCN 14450; Perley, GCN 14451) we detect the optical counterpart
with R=15.5 mag, with a median time of 4.178 hr after the BAT trigger
and calibrated with nearby USNO B1 stars.


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14459
SUBJECT: GRB 130427A: RATIR Optical and NIR Observations
DATE:    13/04/27 13:30:44 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/04 27.34 to 2013/04 27.39 UTC (0.25 to
1.67 hours after the BAT trigger), obtaining a total of 1.07 hours exposure
in the r' and i' bands and 0.45 hours exposure in the Z, Y, J, and H bands.

For a source at afterglow location reported by Elenin et al. (GCN 14450),
in comparison with SDSS DR8 and 2MASS, we obtain the following detections:

  i' 14.46 +/- 0.01
  Z  14.13 +/- 0.03
  Y  14.02 +/- 0.03
  J  14.05 +/- 0.02
  H  13.77 +/- 0.03

These magnitudes are not corrected for Galactic extinction in the direction
of the GRB.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14460
SUBJECT: GRB 130427B: Swift detection of a burst with optical counterpart
DATE:    13/04/27 13:31:58 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Maselli (INAF-IASFPA), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
A. Y. Lien (NASA/GSFC/ORAU), V. Mangano (INAF-IASFPA),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
C. J. Mountford (U Leicester), D. M. Palmer (LANL) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 13:20:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130427B (trigger=554635).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 314.891, -22.530 which is 
   RA(J2000)  =  20h 59m 34s
   Dec(J2000) = -22d 31' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows 3 peaks
with a total duration of about 40 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 13:21:59.1 UT, 77.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 314.89766, -22.54548 which
is equivalent to:
   RA(J2000)  = 20h 59m 35.44s
   Dec(J2000) = -22d 32' 43.7"
with an uncertainty of 4.4 arcseconds (radius, 90% containment). This
location is 59 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 4.41
x 10^20 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 1.15e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 87 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
  RA(J2000)  = 20:59:35.64 = 314.89848
  DEC(J2000) = -22:32:46.5  = -22.54626
with a 90%-confidence error radius of about 1.10 arc sec. This position is 7.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.19. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.07. 

Burst Advocate for this burst is A. Maselli (maselli AT ifc.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130427B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14461
SUBJECT: GRB 130427B: Faulkes Telescope North afterglow detection
DATE:    13/04/27 13:39:57 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), J. Japeli, A. Gomboc
(U. Ljubljana), A. Melandri (INAF-OAB) on behalf of a
large collaboration report:

The 2-m Faulkes Telescope North automatically began observing
GRB 130427B (Maselli et al. GCN Circ. 14460) at 4.6 minutes from
the Swift/BAT trigger time.
The automatic LT-TRAP procedure identified a bright uncatalogued
object at the following position consistent with that reported
by Maselli et al.:

RA=   20:59:35.62
Dec= -22:32:46.9

(J2000).
Its magnitude is estimated to be 15.5 in the R band.


GRB_name: GRB130427A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14462
SUBJECT: GRB 130427A: MAXI/GSC detection
DATE:    13/04/27 15:19:38 GMT
FROM:    Satoshi Nakahira at JAXA/MAXI  <nakahira.satoshi@jaxa.jp>

T. Kawamuro, M. Shidatsu  (Kyoto U.), S. Nakahira (JAXA), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Nakano (AGU),
H. Tsunemi, M. Sasaki (Osaka U.),
M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.),
Y. Ueda, M. Shidatsu (Kyoto U.),
Y. Ueda (Kyoto U.),
Y. Tsuboi, M. Higa (Chuo U.),
M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.),
K. Yamaoka (Nagoya U.) report on behalf of the MAXI team

MAXI/GSC detected the bright GRB 130427A in the scan transit
at 2013-04-27T08:42 UT, about 50 min after the trigger by Swift-BAT (Maselli et al. GCN 14448).
The one-scan averaged 2-10 keV fluxes were 71 +- 19 mCrab and 23 +- 13 mCrab in the scan transits
at 2013-04-27T08:42 and 2013-04-27T10:13, respectively.

There were no significant excess fluxes in the previous scan transit at 07:12 UT and
in the transit at 11:46 with an upper limit of 30 mCrab for each.


GRB_name: GRB130427A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14463
SUBJECT: GRB 130427A: MAXI/GSC detection
DATE:    13/04/27 15:22:47 GMT
FROM:    Satoshi Nakahira at JAXA/MAXI  <nakahira.satoshi@jaxa.jp>

T. Kawamuro, M. Shidatsu  (Kyoto U.), S. Nakahira (JAXA), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Nakano (AGU),
H. Tsunemi, M. Sasaki (Osaka U.),
M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.),
Y. Ueda, M. Shidatsu (Kyoto U.),
Y. Ueda (Kyoto U.),
Y. Tsuboi, M. Higa (Chuo U.),
M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.),
K. Yamaoka (Nagoya U.) report on behalf of the MAXI team

MAXI/GSC detected the bright GRB 130427A in the scan transit
at 2013-04-27T08:42 UT, about 50 min after the trigger by Swift-BAT (Maselli et al. GCN 14448).
The one-scan averaged 2-10 keV fluxes were 71 +- 19 mCrab and 23 +- 13 mCrab in the scan transits
at 2013-04-27T08:42 and 2013-04-27T10:13, respectively.

There were no significant excess fluxes in the previous scan transit at 07:12 UT and
in the transit at 11:46 with an upper limit of 30 mCrab for each.


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14464
SUBJECT: GRB 130427A: Optical Observations
DATE:    13/04/27 15:40:25 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

M. Im (CEOU/SNU) on behalf of a larger collaboration

We observed GRB 130427A (Maselli et al., GCN 14448) 
in BVRI filters using T30 telescope (0.5m) of the iTelescope
network (AAO, Australia), and also are conducting 
follow-up imaging observations using facilities in Korea.

The T30 observation started at about 4 hours after the BAT alert,
and other observations starting at a similar epoch. We clearly 
identify the fading afterglow in T30 images, at the location 
reported earlier (Elenin et al. GCN 14450).

Preliminary BRI magnitudes of the afterglow in one of the epochs, 
calibrated against a USNO B-1 star in the vicinity of the afterglow,
are given below:

   T(mid, UT)         Mag
04-27 11:42:56     I=14.86 +- 0.12
04-27 11:45:29     R=15.60 +- 0.10
04-27 11:50:29     B=16.10 +- 0.15

Follow-up observations are still ongoing.


GRB_name: GRB130427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14465
SUBJECT: GRB 130427A: MITSuME Okayama Optical Observation
DATE:    13/04/27 16:22:27 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427A (Masell et al., GCNC 14448)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 013-04-27 10:57:02 UT (~3.2 h after the burst).
We detected the previously reported afterglow (Elenin et al., GCNC 14450)
in all the three bands.

Photometric results of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'   g'_err Rc    Rc_err Ic    Ic_err
-----------------------------------------------------------------------
0.13478    11:02:01     540.0    15.82  0.03  15.48  0.02  15.04  0.03
0.30675    15:09:39     540.0    16.45  0.06  16.27  0.03  15.87  0.04
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14466
SUBJECT: GRB 130427A: GMG optical observation
DATE:    13/04/27 17:32:43 GMT
FROM:    Xiao-hong Zhao at Yunnan Obs  <zhaoxiaohong78@gmail.com>

X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), Y. X. Xin(YNAO), J.-M. Bai 
(YNAO) report on behalf of a larger collaboration:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope. Observation
was started at 13:25:18 UT on 2013-04-27 (i.e., 5.6 hrs after the burst) under a bad weather condition. The sloan filters of g', r',i' and z' were used. The afterglow is very bright in every band with magnitudes of g'~16.36, r'~16.1, i'~15.9 and z'~15.8. The observations are ongoing. 
   
We thank the GMG staff, especially Hong-Yan Gao and Jian-Duo He for
performing these observations.


GRB_name: GRB130427B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14467
SUBJECT: GRB 130427B: Enhanced Swift-XRT position
DATE:    13/04/27 17:43:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1221 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 130427B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 314.89849, -22.54670 which is equivalent
to:

RA (J2000): 20h 59m 35.64s
Dec (J2000): -22d 32' 48.1"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14468
SUBJECT: GRB 130427A: Zadko observatory - Gingin optical observations
DATE:    13/04/27 17:43:48 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

B. Gendre, A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR),
D. Coward (UWA), M. Boer, K. Siellez, H. Dereli ,
O. Bardho (UNS-CNRS-ARTEMIS-OCA), A. Williams (PO-UWA),
R. Martin (PO-UWA) report:

We imaged the field of GRB 130427A detected by SWIFT
(trigger 554620) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 3.44h after the GRB trigger
(the event occured during the local afternoon).
The elevation of the field increased from
23 degrees above horizon and weather conditions
were good.

We detect the optical couterpart discovered by
Elenin et al. (GCNC 14450). The unfiltered images
are analyzed regarding the R magnitude of star
catalogues. The preliminary light curve is:

Tstart Tstop Rmag  1sig
(mins) (mins)
    207   219 15.50 0.1
    220   232 15.54 0.1
    238   250 15.37 0.1
    252   264 15.56 0.1
    265   277 15.51 0.1
    304   319 15.58 0.1
    447   450 16.27 0.2

Magnitudes are not corrected for galactic dust extinction.

This message may be cited.


GRB_name: GRB130427B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14469
SUBJECT: GRB 130427B: Swift-BAT refined analysis
DATE:    13/04/27 18:55:42 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), A. Maselli (INAF-IASFPA),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130427B (trigger #554635)
(Maelli, et al., GCN Circ. 14460).  The BAT ground-calculated position is
RA, Dec = 314.900, -22.548 deg, which is 
   RA(J2000)  =  20h 59m 36.0s 
   Dec(J2000) = -22d 32' 51.6" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 22%.
 
The mask-weighted light curve shows shows a very small peak at ~T-3 sec,
the main peak starting at ~T-1 sec, peaking at ~T+2 sec, and ending at
~T+40 sec.  T90 (15-350 keV) is 27.0 +- 7.3 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-1.29 to T+32.71 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.64 +- 0.15.  The fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+0.71 sec in the 15-150 keV band
is 3.0 +- 0.4 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/554635/BA/


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14470
SUBJECT: GRB 130427A: Swift-BAT refined analysis
DATE:    13/04/27 19:33:00 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), A. Maselli (INAF-IASFPA),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130427A (trigger #554620)
(Maselli, et al., GCN Circ. 14448).  The BAT ground-calculated position is
RA, Dec = 173.150, 27.706 deg which is 
   RA(J2000)  =  11h 32m 36.1s 
   Dec(J2000) = +27d 42' 20.3" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 14%.
 
The mask-weighted light curve shows the main emission occuring during a
pre-planned slew.  The burst location came into the BAT FoV at ~T-52 sec.
The first recorded peak started at ~T-51 sec and ending at ~T-50 sec.
The main, large peak started at ~T-50 sec, peaked at ~T-42 sec (~310 cnts/cm2/sec),
and ended at ~T-10 sec.  The spacecraft settled at T+0, and then BAT triggered
(a 64-sec image trigger) at the beginning a long slow peak starting at ~T+0 sec,
peaking at ~T+90 sec, and returning to baseline ~T+2000 sec.
T90 (15-350 keV) is 162.83 +- 1.36 sec (estimated error including systematics).
We note that (a) there is a possibility that there was emission from this burst
before it came into the BAT FoV at ~T-52 sec, and (b) that Fermi-GBM triggered
on this burst at 07:47:06.42 (T_bat-51 sec) [GCN/FERMI_GBM_FLIGHT_POSITION Notice,
TrigNum=388741629].
 
The time-averaged spectrum from T-51.05 to T+223.50 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.21 +- 0.02.  The fluence in the 15-150 keV band is 3.1 +- 0.03 x 10^-4 erg/cm2.
The 1-sec peak photon flux measured from T-44.25 sec in the 15-150 keV band
is 331.0 +- 4.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/554620/BA/


GRB_name: GRB130427A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14471
SUBJECT: GRB 130427A: Fermi-LAT detection of a burst
DATE:    13/04/27 20:10:41 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin@nasa.gov>

S. Zhu, J. Racusin, D. Kocevski, J. McEnery (NASA/GSFC), F. Longo (Univ of Trieste and INFN), J. Chiang (SLAC), G. Vianello (Stanford) report on behalf of the Fermi-LAT team:

At 07:47:06 UT on 27 April 2013, Fermi LAT detected high energy emission from GRB 130427A, which was also detected by Fermi-GBM (trigger 388741629/130427324) and by Swift (Maselli et al. GCN 14448).  The GBM detection triggered an autonomous repoint of the spacecraft.

The LAT on-ground location is consistent with the optical position reported in Elenin et al. (GCN 14450). The burst was about 47 deg from the LAT boresight at the time of the trigger and within the LAT field of view for the next 700 seconds.

The data from the Fermi LAT show a multi-peaked light curve consistent with the GBM trigger. More than 200 photons above 100 MeV are observed within 100 seconds with a TS of >1000.  Using the non-standard LAT Low Energy (LLE) data selection, thousands of counts above background were detected within a 100 s interval coinciding with the time of the GBM emission, with a significance of ~40 sigma. The highest energy LAT photon has an energy of 94 GeV.

A GBM circular is forthcoming.

The Fermi LAT point of contact for this burst is Sylvia Zhu (s.jc.zhu@gmail.com).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

[GCN OPS NOTE(30apr13): Per author's request, time in the first sentence was changed from "07:47:15" to "07:47:06".]


GRB_name: GRB130427A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14472
SUBJECT: GRB130427A: Swift/UVOT followup observations of an Optical Afterglow
DATE:    13/04/27 20:22:45 GMT
FROM:    Tyler Pritchard at PSU  <tapritchard@astro.psu.edu>

T. Pritchard (PSU), A. Maselli (INAF-IASFPA), N. P. M. Kuin (MSSL),
S. R. Oates (MSSL-UCL), M. De Pasquale (MSSL-UCL),
and M. H. Siegel (PSU), report on behalf of the Swift/UVOT team:

Further to Maselli et al., GCN Circ. 14448 we have performed manual
stacking and aspect corrections on the initial UVOT image.  These
resulting images still retain some instrumental effects due to the
brightness of the object and loss of star tracking lock.

Preliminary 3-sigma detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the UVOT
observations are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
wh          1522         1542           19.5         13.81.1
v         382          401           19.5        12.10.04
b            480          500           19.5        12.61.09
u            456          475           19.5        11.81.09
w1           430          450           19.5        11.20.04
m2           406          426           19.5        11.20.04
w2           358          377           19.5        11.20.04

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.24 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB130427A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14473
SUBJECT: GRB 130427A: Fermi GBM observation
DATE:    13/04/27 20:27:19 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 07:47:06.42 UT on 27 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130427A (trigger 388741629/130427324) which
was also detected by the Swift/BAT and Fermi/LAT (Maselli et al. 2013, 
GCN 14448  and S. Zhu et al., GCN 14471) The GBM on-ground location is 
consistent with the Swift position.

The angle from the Fermi LAT boresight is 48 degrees.

Based on hard and intense emission in a GBM BGO detector, GBM 
initiated an Autonomous Report Request. This request caused Fermi 
to reorient towards this GRB (GBM flight location).  

The GBM light curve consists of a bright structured peak followed 
at ~T0+120 s by a FRED-like pulse. The overall duration (T90) 
is about 138s s (50-300 keV).

Owing to the brightness of the burst, systematic effects are very large 
and no single model gives an adequate fit in this preliminary analysis.  
A Band function fit in the interval  from T0+0.002 s to T0+18.432 s yields 
the following parameters Epeak = 830 +/- 5 keV, alpha = -0.789 +/- 0.003, 
and beta = -3.06 +/- 0.02. 

The event fluence (10-1000 keV) in this time interval is
(1.975 +/- 0.003)E-03 erg/cm^2. The 1.024 sec peak photon flux measured
starting from T0+7.48808 s in the 8-1000 keV band
is 1052 +/- 2 ph/s/cm^2, making this the most intense and fluent GRB 
detected by Fermi GBM.

Further analysis is being performed"


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14474
SUBJECT: GRB 130427A: optical observations in CrAO
DATE:    13/04/27 21:13:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova ( IKI),   D. Shakhovskoy (CrAO),   V. Rumyantsev (CrAO), A. 
Pozanenko (IKI) report on behalf of  larger GRB  follow-up collaboration:

We started observation of the field of  the Swift GRB 130427A (Maselli et 
al., GCN 14448)  with AZT-11 telescope of CrAO observatory on Apr. 27 (UT) 
18:21:45 in VRI filters. We clearly detect  still bright optical counterpart 
of GRB 130427A (Maselli et al., GCN 14448, Elenin et al. GCN 14450, Perley 
GCN 14451).    Preliminary photometry is following

   filter   tstart (UT) exp,s   T-t0,d       OT +/- err
   R       18:21:45   120      0,76580   16,71 +/- 0,06
   R       18:27:52   120      0,77005   16,87 +/- 0,06
   R       18:34:00   120      0,77431   16,83 +/- 0,07
   R       18:40:07   120      0,77855   16,81 +/- 0,06

Observation is continuing.


GRB_name: GRB130427A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14475
SUBJECT: GRB 130427A: T100 observations
DATE:    13/04/27 22:39:19 GMT
FROM:    Eda Sonbas at NASA/GSFC  <edasonbas@gmail.com>

E. Sonbas (Adiyaman Univ.), T. Guver (Sabanci Univ.), E. Gogus (Sabanci
Univ.), H. Kirbiyik (TUG) report on behalf of a larger collaboration

We observed the field of Swift  GRB 130427A (Maselli et al. GCN#14448)
with  the  1.0 meter  T100  telescope  (TUBITAK National  Observatory,
Antalya - Turkey),  starting April, 27, 20:39:28 UT (~ 13 hours after
the trigger). Observations were carried out in the R filter under good
weather conditions. The afterglow is clearly  detected in 60 s R band
images at a position that is consistent with Elenin et al. GCN#14450

Using USNO-B1 star USNO-B1 1177-0254824  (RA=  11:32:31.23, Dec=
+27:42:23.02 ) in the field, the magnitudes of the OT were estimated as
follows;

t-t0 (hr)         exp.(s)      filt            mag             err (+/-)
12.850        60               R            16.2              0.05
12.871        60               R            16.6              0.03
12.874        60               R            16.3              0.03
12.877        60               R             16.5             0.01

Further observations using the same filter are ongoing.

We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their technical support.


GRB_name: GRB130427A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14476
SUBJECT: GRB 130427A: RAPTOR Bright Counterpart Before Swift Trigger
DATE:    13/04/28 00:12:42 GMT
FROM:    James Wren at LANL  <jwren@nis.lanl.gov>

J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:

Three RAPTOR full-sky persistent monitors at Maui, HI, and Los Alamos, NM,
independently detected  bright optical emission at the location of the
Swift trigger 554620 (Maselli, et al., GCN 14448).  Starting at 07:47:07.28
UT (50.2 seconds before the Swift trigger) we detect a brightening counterpart
which peaks at magnitude R~7.4.  After the peak, the source fades to below
10th magnitude at approximately the Swift trigger time.  The unfiltered images
from all three monitors are calibrated to the Tycho-2 V-band catalog.


GRB_name: GRB130427B
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14477
SUBJECT: GRB 130427B: MITSuME Okayama upper limits
DATE:    13/04/28 00:28:48 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427B (Maselli et al., GCNC 14460)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-04-27 18:47:30 UT (~5.4 h after the burst).
We did not find any new point source within the enhanced XRT circle
(Osborne et al., GCNC 14467) in all the three bands.

Photometric results of the OT are listed below.
We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.22892    18:50:19    2160.0   >18.0  >18.3  >17.9
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14478
SUBJECT: GRB 130427A: NOT optical photometry and redshift
DATE:    13/04/28 00:47:29 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), S.
Schulze (PUC and MCSS), J. Jessen-Hansen (AU), G. Leloudas (OKC,
Stockholm), T. Kruehler, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (U.
Iceland) report on behalf of a larger collaboration:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) with
the 2.5m Nordic Optical Telescope (NOT) equipped with the ALFOSC
camera. Observations started at 20:39:12 UT on 2013-04-27 (i.e., 12.85
hr after the BAT trigger).

We first obtained a series of frames in the sloan u-, g-, r-, i-, and
z-band filters. The optical afterglow (ref., Elenin et al., GCN 14450)
is clearly detected in the stacked images in each of these filters.
Preliminary analysis gives the following magnitudes

u=17.70+/-0.03
g=17.34+/-0.03
r=17.07+/-0.03
i=16.94+/-0.03
z=16.88+/-0.03

at a mean time of 12.96 hr post-trigger, calibrated with nearby stars
in the SDSS field.

We also carried out a 1800s spectroscopic exposure. The spectrum
covers 3200 - 9100 AA at a resolution of ~700 and has a high S/N. We
detect prominent absorption lines of the MgII doublet, MgI and CaII K
& H as well as weak emission lines of the [OII] doublet and H-beta,
all at a common redshift of z=0.338+/-0.002, consistent with the
redshift reported by Levan et al. (GCN 14455).


GRB_name: GRB130427B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14479
SUBJECT: GRB 130427B: Swift-XRT refined Analysis
DATE:    13/04/28 01:32:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. Mangano (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C.
Stroh (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU) and A. Maselli report on behalf of the Swift-XRT team:

We have analysed 7.3 ks of XRT data for GRB 130427B (Maselli  et al.
GCN Circ. 14460),  from 67 s to 24.2 ks after the  BAT trigger. The
data comprise 120 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by
Osborne et al. (GCN. Circ 14467).

The late-time light curve (from T0+11.6 ks) can be modelled with  a
power-law decay with a decay index of alpha=1.9 (+0.6, -0.5).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.93 (+0.14, -0.13). The
best-fitting absorption column is  8.3 (+2.8, -2.6) x 10^20 cm^-2, in
excess of the Galactic value of 4.4 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.79 (+0.23, -0.11)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.9 x 10^-11 (4.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      0 (+4.7, -0) x 10^20 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.79 (+0.23, -0.11)

If the light curve continues to decay with a power-law decay index of
1.9, the count rate at T+24 hours will be 9.7 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x
10^-14 (4.2 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00554635.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14480
SUBJECT: GRB 130427A:  VLA 5 GHz detection
DATE:    13/04/28 03:38:35 GMT
FROM:    Ashley Zauderer at CfA  <bevinashley@gmail.com>

B. A. Zauderer, E. Berger, S. Chakraborti, and A. Soderberg (Harvard)
report on behalf of a larger collaboration:

"We observed the position of GRB 130427A (Maselli et al.; GCN 14448)
beginning 2013 Apr 27.99 (dt = 0.67 d) with the Very Large Array in its
D configuration (synthesized beam ~18'' x 11'').  At a mean frequency of 
~5.8 GHz, we detect a source with a flux of ~1 mJy +/- 20 uJy at a
position consistent with the optical afterglow (e.g. Elenin et al., 
Perley et al.; GCNs 14450, 14451). Followup observations are planned for 
this nearby z~0.34 GRB (Levan et al., Xu et al; GCNs 14455, 14478).

We thank the VLA observatory staff for their support of these observations."


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14481
SUBJECT: GRB 130427A: SNUO/SOAO/BOAO Observation
DATE:    13/04/28 03:47:29 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

M. Im, C. Choi (CEOU/SNU), H.-I. Sung, Y.-B. Jeon (KASI), 
and Y. Urata (NCU) on behalf of a larger collaboration

We continued our follow-up imaging observation of
GRB 130427A (Maselli et al., GCN 14448) in BVRI filters at 
Seoul National University Observatory (SNUO, 0.6m), Sobaeksan 
Optical Astoronomy Observatory (SOAO, 0.6m), and Bohyunsan 
Optical Astronomy Observatory (BOAO), all located in Korea.

The observations span the time period of about 4 hrs 
between 04-27 11:28 and 04-27 15:48 UT. The GRB afterglow 
(e.g., Elenin et al. GCN 14450; Im GCN 14464) is identified 
in the observed frames at magnitudes of ~16-17 mag

Further analysis of the data is ongoing, and additional follow-up 
observation with these and other facilities is ongoing and planned.

We thank the staffs of SOAO for performing the ToO observation.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14482
SUBJECT: GRB 130427A:  CARMA 85 GHz detection
DATE:    13/04/28 05:22:11 GMT
FROM:    Ashley Zauderer at CfA  <bevinashley@gmail.com>

B. A. Zauderer, E. Berger, S. Chakraborti, and A. M. Soderberg (Harvard) 
report on behalf of the CARMA Key Project "A Millimeter View of the 
Transient Universe":

"We began observing the field of GRB 130427A (Maselli et al.; GCN 14448) 
with the Combined Array for Research in Millimeter Astronomy on 2013 Apr 
28.13 UT (dt ~ 0.8 d).  In 45 minutes integration on source at a mean 
frequency of 85 GHz, we detect a radio counterpart with a preliminary 
flux of ~3 mJy (>10-sigma) at a position consistent with the reported 
optical afterglow (Elenin et al., Perley et al.; GCNs 14450, 14451) and 
our VLA 5 GHz detection (Zauderer et al.; GCN 14480). Observations are 
ongoing.

We thank the CARMA observers and the observatory staff for their support."


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14483
SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations
DATE:    13/04/28 05:46:39 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We again observed the field of GRB 130427A (Maselli, et al., GCN 14448)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico
Nacional on Sierra San Pedro Mrtir from 2013/04 28.14 to 2013/04 28.20 UTC
(19.62 to 20.99 hours after the BAT trigger), obtaining a total of 1.07
hours exposure in the r' and i' bands and 0.45 hours exposure in the Z, Y,
J, and H bands.

We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450)
in all bands.  In comparison with SDSS DR8 and 2MASS, we find:

  r'    17.68 +/- 0.01
  i'    17.52 +/- 0.01
  Z     17.26 +/- 0.04
  Y     17.12 +/- 0.02
  J     17.21 +/- 0.02
  H     17.01 +/- 0.03

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertaints are 1-sigma.  The
source has faded by about 3 magnitudes in all bands as compared to our
measurements last night (Butler et al. 2013; GCN 14459).

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14484
SUBJECT: GRB 130427A: SPI-ACS/INTEGRAL observations
DATE:    13/04/28 06:38:27 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), P. Minaev (IKI), A. Volnova (IKI) report:

The SPI-ACS detector (> 80 keV) of INTEGRAL observatory was triggered by the 
Swift GRB 130427A  (Maselli et al., GCN 14448) on (UT) T0=07:47:06.36. Light 
curve of the GRB 130427A 
(http://www.isdc.unige.ch/integral/ibas/cgi-bin/ibas_acs_web.cgi) consists 
of the first peak of ~ 1 s duration  which coincides with bright optical 
emission detected by RAPTOR (Wren et al., GCN 14476). This peak is also 
clearly visible in the BAT light curve at ~T0_BAT-51 s ( 
http://gcn.gsfc.nasa.gov/notices_s/554620/BA/ ). Following the first peak 
extremely intense emission was detected coinciding with BAT/Swift and 
Fermi-LAT detection (Zhu et al., GCN 14471). The emission in SPI-ACS 
detector is significantly detectable at least up to 100 s after T0.

The SPI-ACS light curve can be also found at
http://grb.rssi.ru/GRB130427A/GRB130427A_SPI-ACS.png


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14485
SUBJECT: GRB 130427A: Swift-XRT refined Analysis
DATE:    13/04/28 08:29:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.
Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC)
and A. Maselli report on behalf of the Swift-XRT team:

We have analysed 2.4 ks of XRT data for GRB 130427A (Maselli  et al.
GCN Circ. 14448),  from 130 s to 48.1 ks after the  BAT trigger. The
data comprise 84 s in Windowed Timing (WT) mode (the first 9 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The refined XRT position is RA, Dec = 173.13594, +27.69769
which is equivalent to:

RA (J2000): 11 32 32.63
Dec(J2000): +27 41 51.7

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=7.9980 (+0.0021, -1.0800), followed by a break at T+252
s to an alpha of 0.61 (+/-0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.79 (+0.17, -0.16). The
best-fitting absorption column is  9.9 (+6.4, -6.0) x 10^20 cm^-2, at a
redshift of 0.34, in addition to the Galactic value of 1.8 x 10^20
cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed)
0.3-10 keV flux conversion factor deduced from this spectrum  is 4.0 x
10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 1.8 x 10^20 cm^-2
Intrinsic column:    9.9 (+6.4, -6.0) x 10^20 cm^-2 at z=0.34
Photon index:      1.79 (+0.17, -0.16)

If the light curve continues to decay with a power-law decay index of
0.61, the count rate at T+24 hours will be 2.3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.4 x
10^-11 (1.1 x 10^-10) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00554620.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14486
SUBJECT: GRB 130427A: Kanata/HOWPol optical imaging polarimetry
DATE:    13/04/28 10:21:20 GMT
FROM:    Koji Kawabata at HASC,Hiroshima U  <kawabtkj@hiroshima-u.ac.jp>

R. Itoh, K. Kawaguchi, Y. Moritani, K. Takaki, K. S. Kawabata, M. Ohno, 
H. Takahashi, Y. Tanaka, and M. Yoshida (Hiroshima Univ.) report on behalf 
of Kanata team:

We performed a series of optical imaging polarimetry for the optical 
afterglow of GRB 130427A (Elenin et al., GCN 14450) from 3.87 hr through
10.04 hr after the Swift/BAT trigger (Maselli et al., GCN 14448) with HOWPol 
attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Japan. 

Our quick-look analysis indicates that the R-band magnitude of the optical 
afterglow was 15.9 at the beginning of our observation, and then smoothly 
declined. Its decline rate between 3.87 hr and 10.04 hr can be approximated by 
a single power-low decay with an index -1.0. The polarization seems not so 
large (<~3%) in that period. Further analysis is ongoing.


GRB_name: GRB130427A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14487
SUBJECT: Konus-Wind observation of GRB 130427A
DATE:    13/04/28 10:22:50 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long extremely intense GRB 130427A (Swift-BAT trigger #554620:
Maselli et al., GCN 14448; Barthelmy et al., GCN 14470;
Fermi-LAT detection: Zhu et al., GCN 14471;
Fermi-GBM observation: von Kienlin, GCN 14473;
SPI-ACS/INTEGRAL observations: Pozanenko et al., GCN 14484)
triggered Konus-Wind (K-W) at T0=28029.501s UT (07:47:09.501)
~50 s before the BAT trigger.

The K-W light curve shows a huge mult-peaked emission complex
started at ~T0, peaked at ~T0+8 s, and having a duration of ~20 s.
The emission is seen up to ~12 Mev.
This extremely bright phase of the event passes into a weaker decaying
tail out to ~T0+120s, when the second emission episode started.
It shows a FRED-like pulse, ~100 times weaker in a peak count
rate than the initial complex.
The decaying emission is detectable by K-W in the 20-1200 keV band
out to ~T0+250s, when the instrument switched into the data readout mode.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130427_T28029/

As observed by Konus-Wind, the main phase of the burst had
a fluence of (2.68  0.01)x10^-3 erg/cm2 and a 16-ms peak flux,
measured from T0+7.774 s, of (6.9  0.1)x10^-4 erg/cm2/s
(both in the 20 - 1200 keV energy range).
The fluence of GRB 130427A is the highest observed by K-W
for ~18 years of GRB observations and its peak flux
is only ~30% lower than measured by K-W for the
ultra-luminous GRB 110918A.

The time-averaged spectrum of the main phase of the burst
(measured from T0 to T0+18.688 s) is best fit in the 20 keV-15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.958  0.006,
the high energy photon index beta = -4.17  0.16,
the peak energy Ep = 1028  8 keV,
chi2 = 124/96 dof.

The spectrum at the maximum count rate (measured from T0+7.680 to T0+7.936 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model, for which:
the photon index alpha = -0.57  0.02, and
the peak energy Ep = 1213  31 keV,
chi2 = 63/84 dof.

Modelling the 3-channel time-averaged spectrum
of the second emission episode (from T0+120 s to T0+250 s)
by a power law with exponential cutoff model
yiels the photon index alpha~-1.6 and
the peak energy Ep ~ 240 keV.
The 20-1200 keV energy fluence measured at this
phase of the event is ~9x10^-5 erg/cm2.

Assuming z=0.34 (Levan et al., GCN 14455; Xu et al. GCN 14478)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
the isotropic energy release E_iso is ~8.5x10^53 erg,
and the peak luminosity (L_iso)_max is ~2.7x10^53 erg/s.

All the quoted errors are estimated at the 1 sigma confidence level.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14488
SUBJECT: GRB 130427A: Continued iTelescope T21 optical observations
DATE:    13/04/28 11:37:46 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:

We have continued observing GRB 130427A optical afterglow at iTelescope
observatory T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph and
FLI-PL6303E CCD. Two unfiltered, two photometric R filter and two
photometric V filter images with 600 sec exposure time were made.

The following magnitudes were obtained from the observations using
NOMAD1 1176-0248446 (R=13.520, V=13.120) as the comparison:

Tmid(h)+T0      Filter     Exp. time         Mag          Mag err. 
22.67              V              600                17.73V         0.11
22.85              V              600                17.72V         0.11
23.10              unfiltered   600                18.01CR       0.07
23.27              unfiltered   600                18.22CR       0.09
23.56              R              600                18.18R          0.12
23.74              R              600                18.36R          0.14


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14489
SUBJECT: GRB 130427A, Optical Observations
DATE:    13/04/28 11:48:15 GMT
FROM:    Shashi Bhushan Pandey at ROTSE  <shaship@umich.edu>

S. B. Pandey and Brajesh Kumar (ARIES Nainital India, on behalf of larger
Indian GRB collaboration)

We observed Swift GRB 130427A field (Maselli et al., GCN 14448) using 1.04m
telescope at ARIES Nainital on 2013-04-27 starting at 14:25:16 UT in
UBV(RI)_c filters. Several frames were obtained in average sky conditions.

We clearly detect the bright optical counterpart of GRB 130427A (Maselli et
al. GCN 14448, Elenin et al. GCN 14450) in each individual exposures.

The preliminary photometry is as following:

 (UT)Start    filter    exp(sec)      mag
 14:25:16       B        300        16.61 +/- 0.06
 14:53:36       I         200       14.83 +/- 0.05

The photometry was performed in comparison to nearby USNO- B1 stars. Our
observations seem to follow the power-law decay exponent ~ -0.9 as noticed 
by Perley and Cenko GCN 14456.

Further observations are going on. This massage may be cited.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14490
SUBJECT: GRB 130427A optical time series
DATE:    13/04/28 13:46:40 GMT
FROM:    AAVSO GRB Network at AAVSO  <matthewt@aavso.org>

Patrick Wiggins (Stansbury Park, Utah, United States) reports the following 
optical observations of the error box of GRB 130427A (GCN Circ #14448,
Maselli et al.) to the AAVSO International High Energy Network:

P. Wiggins reports three hours of time-series photometry of the bright GRB 
130427A (Maselli et al., GCN Circ. #14448; Elenin et al., GCN Circ. # 
14450). Wiggins used a 0.35-m C-14 f/5.5 telescope with an SBIG ST-10XME 
camera and clear filter located in Stansbury Park, Utah.  Observations 
commenced 2013 April 27 08:05:12 UT -- less than 20 minutes post trigger 
-- and continued through 11:10:06 UT.  The first four observations were 
made with 60-second exposure times, which were found to be close to 
saturation; subsequent exposure times were 30 seconds.  The transient was 
detected by visual inspection of the first frame, and found to be very 
bright.  Time-series observations were begun immediately.

Thirty-three images of the field were taken, and the resulting light curve 
is as follows.  All magnitudes are taken with respect to the comparison 
star GSC 01984-00021, which has an r-magnitude of 12.553 (APASS DR7, 
http://www.aavso.org/apass ); the resulting magnitudes should be 
interpreted as through a clear filter with r'-band zero point.  Note that 
the first four magnitudes with integration times of 60 seconds may be 
saturated.  All times are given as the mid-point of the exposure, UT on 
2013 April 27, and T(0)+h is hours since trigger (07:47:57 UT):

     Obs. UT T(0)+h Exp. time magn. mag.err.
08:05:41.529 0.296    60.00 13.108  0.006
08:06:57.779 0.317    60.00 13.194  0.007
08:14:16.467 0.439    60.00 13.557  0.009
08:27:07.951 0.653    60.00 13.995  0.013
08:40:35.701 0.877    30.00 14.304  0.024
08:46:36.857 0.978    30.00 14.413  0.027
08:50:51.998 1.049    30.00 14.47  0.029
08:55:17.311 1.122    30.00 14.546  0.030
09:00:52.545 1.215    30.00 14.623  0.033
09:06:26.014 1.308    30.00 14.684  0.035
09:11:59.514 1.401    30.00 14.731  0.038
09:17:33.139 1.493    30.00 14.792  0.041
09:23:06.748 1.586    30.00 14.829  0.043
09:28:40.357 1.679    30.00 14.969  0.050
09:34:18.373 1.773    30.00 14.957  0.050
09:39:51.873 1.865    30.00 14.911  0.050
09:45:25.545 1.958    30.00 15.025  0.055
09:50:59.404 2.051    30.00 15.158  0.064
09:56:32.982 2.143    30.00 15.104  0.064
10:02:06.529 2.236    30.00 15.22  0.073
10:07:40.154 2.329    30.00 15.138  0.071
10:13:13.732 2.421    30.00 15.249  0.080
10:15:01.029 2.451    30.00 15.219  0.078
10:20:47.498 2.547    30.00 15.302  0.088
10:26:21.123 2.64    30.00 15.424  0.099
10:31:54.732 2.733    30.00 15.387  0.100
10:37:28.451 2.825    30.00 15.247  0.091
10:43:02.248 2.918    30.00 15.512  0.123
10:48:35.811 3.011    30.00 15.496  0.124
10:54:09.561 3.103    30.00 15.517  0.128
10:59:43.279 3.196    30.00 15.633  0.150
11:05:19.092 3.289    30.00 15.555  0.150
11:10:20.982 3.373    30.00 15.48  0.153

The AAVSO International High Energy Network is supported through the
AAVSO Endowment Fund.  We thank the Charles Curry Foundation and
NASA for past support.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14491
SUBJECT: GRB 130427A: VLT/X-shooter redshift confirmation
DATE:    13/04/28 15:05:53 GMT
FROM:    Hector Flores at Obs.de Paris,Meudon  <hector.flores@obspm.fr>

GRB 130427A: VLT/X-shooter redshift confirmation

H. Flores (Obs. de Paris), S. Covino (INAF), D. Xu, T. Kruehler,
J. Fynbo, B. Milvang-Jensen(DARK/NBI), A. de Ugarte Postigo (IAA-CSIC,
DARK/NBI), L. Kaper (UVA) and  K. Wiersema (U. Leicester) report on behalf
of the X-shooter GRB collaboration:

VLT/X-shooter observed the afterglow of GRB 130427A (Maselli et al.,
GCN 14448; Elenin et al., GCN 14450), starting on 2013-04-28 at UT
00:23. The observation consisted of 2x600s exposures.

In the spectra we detect the continuum in the complete range from 3000
to 24800 A. We find several absorption features including FeII, MnII,
MgII, MgI, TiII, CaII, NaI, and emission lines such as H-alpha,
H-beta,  [OIII], and [OII], all at a common redshift of z=0.3399 +/- 0.0002,
consistent with the measurement in Levan et al. (GCN 14455) and
Xu et al. (GCN 14478).

We thank the Paranal staff for excellent support, in particular Andrea
Mehner and Christophe Martayan.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14492
SUBJECT: GRB 130427A : Xinglong TNT optical observation
DATE:    13/04/28 17:55:49 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L.P. Xin, J. Y. Wei, Y. L. Qiu,  J. Wang, 
J. S. Deng, C. Wu, X.H. Han  report on behalf of EAFON team:

We began to observe the field of GRB 130427A  (Maselli, et al., GCN 14448)
using  80cm TNT telescope located at Xinglong observatory, China
at 12:52:38 UT on 2013-04-28.  We obtained several B, V, R-band images.  

The optical counterpart is detected in all images. The prelinary analysis shows that
its brightness is about R=18.3 mag, calibrated with USNO B2 stars, 
at the mean time of  29.08 h after the trigger time.

This message may be cited.


GRB_name: GRB130427B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14493
SUBJECT: GRB 130427B: Tentative VLT/X-shooter redshift
DATE:    13/04/28 18:13:02 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

H. Flores (GEPI/Obs. de Paris),  S. Covino (INAF),  A. de Ugarte
Postigo (IAA-CSIC, DARK/NBI), J. Fynbo, T. Kruehler, D. Xu (DARK/NBI)
and N. Tanvir (U. Leicester)  report on behalf of the X-Shooter GRB
collaboration:

We have observed the afterglow of the GRB 130427B (Maselli et al., GCN
14460) with the ESO VLT equipped with the X-shooter spectrograph. The
observation started on  2013-04-28 at 9:45 UT. A total exposure of
2x600 s was obtained just before morning twilight, covering the
spectral range from 300 to 2500 nm.

In the spectrum we detect a  feature consistent with a damped
Lyman-alpha line in the UVB arm at redshift of z=2.78 +/-  0.02. Given
the low S/N of the spectrum, this redshift measurement should be
considered tentative.

We thank the Paranal staff for enthusiastic support, in particular
Andrea Mehner and Christophe Martayan.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14494
SUBJECT: GRB 130427A: CARMA 3mm observations
DATE:    13/04/28 22:38:23 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration:

We observed the position of GRB 130427A (Maselli et al.; GCN 14448) with 
the Combined Array for Research in Millimeter Astronomy on two epochs on 
2013-04-28 (UT), between 01:45 and 02:46 and again between 07:22 and 
08:14, at a frequency of 93 GHz (3 mm).  The afterglow is well-detected 
in both epochs.  Preliminary reduction gives fluxes of:

3.7 +/- 0.4 mJy  (t_mid = 0.769 day)
2.6 +/- 0.4 mJy  (t_mid = 1.000 day)

These values are consistent with the flux reported by Zauderer et al. 
(GCN 14482) as also measured by CARMA at a time intermediate between 
these epochs.

The source location is:

RA = 11:32:32.82
Dec = +27:41:56.06
(J2000, uncertainty 0.4 arcsec)

Further observations are planned.

We thank the CARMA staff for their support in executing these observations.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14495
SUBJECT: GRB 130427A: Nishi-Harima NIR Observations
DATE:    13/04/29 00:11:01 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

J. Takahashi, K. Morihana, S. Honda and Y. Takagi (Univ. of Hyogo)
report on behalf of Nayuta team:

We observed the field of GRB 130427A (Masell et al., GCNC 14448)
in near-infared three bands (J, H and Ks) with NIC attached to the
Nayuta 2-m telescope at the Nishi-Harima Astronomical Observatory.

The observations were conducted from 2013-04-27 12:26 UT to 2013-04-27
17:25 UT (from ~4.7 h to ~9.6 h after the burst).
We detected the previously reported afterglow (Elenin et al., GCNC 14450)
in all the three bands.

Photometric results of our observations are listed below.
We used 2MASS 11323755+2743196 as the reference star for flux calibration.

# MID-UT   T-EXP[sec]  J    J_err H    H_err  Ks    Ks_err
-----------------------------------------------------------------------
12:26:56     150       14.7  0.2  13.5  0.2   13.5   0.2
13:27:59     150       14.7  0.2  14.2  0.2   13.2   0.3
14:39:42     150       14.7  0.3  14.3  0.2   13.4   0.3
17:17:31     150       --*   --*  14.8  0.2   14.6   0.2
17:24:52     300       15.2  0.2  14.8  0.2   14.0   0.2
------------------------------------------------------------------------
T-EXP: Total Exposure time [sec]
* Photometry was not possible because the signal from the reference star
was too low.


GRB_name: GRB130427B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14496
SUBJECT: GRB 130427B: RATIR Optical and NIR Observations
DATE:    13/04/29 01:39:53 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130427B (Maselli, et al., GCN 14460) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/04 28.44 to 2013/04 28.48 UTC (21.26 to
22.19 hours after the BAT trigger), obtaining a total of 0.71 hours
exposure in the r' and i' bands and 0.29 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Osborne, et al., GCN
14467), in comparison with USNO-B1 and 2MASS, we obtain the following upper
limits (3-sigma):

  r' > 22.08
  i' > 22.06
  Z  > 21.28
  Y  > 20.77
  J  > 20.57
  H  > 19.84

These limits,  in the AB system and not corrected for Galactic extinction
in the direction of the GRB, were derived from PSF-fitting photometry,
because of the presence of a 16.5 magnitude star only 5 arcseconds to the
south of the SWIFT-XRT source position.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14497
SUBJECT: GRB 130427A: Skynet/PROMPT Observations
DATE:    13/04/29 05:45:38 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, T. Berger, H. T. 
Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. 
Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:

Skynet observed the Swift/XRT localization of GRB 130427A (Maselli et 
al., GCN 14448, Swift trigger #554620) with four 16" telescopes of the 
PROMPT array at CTIO, Chile, starting at 2013-04-27, 23:28 UT, and 
continuing until 04-28, 05:30 UT (t=15.69h-21.67h post-trigger). It took 
~124 160-s exposures, simultaneously in each of the BVRI bands. We 
performed photometry on each exposure, calibrated to two SDSS stars in 
the field. We detect a fading afterglow in BVRI at the position reported 
by Elenin et al. (GCN 14450), which is ~50" south of the initial XRT 
localization.

A preliminary light curve of the first night's data is at:
http://skynet.unc.edu/grb/grb130427a.png

Further Skynet observations are ongoing.


GRB_name: GRB130427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14498
SUBJECT: GRB 130427A: MITSuME Okayama and Ishigakijima Optical Observation after 1 day
DATE:    13/04/29 06:06:15 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa,
Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, NAOJ),
S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427A (Masell et al., GCNC 14448)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory
and the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

We detected the previously reported afterglow (Elenin et al., GCNC 14450)
in all the three bands. Photometric results of the OT are listed below.
We used SDSS catalog for flux calibration.

Okayama Astrophysical Observatory:
The observation started on 2013-04-28 11:29:25 UT (~1.15 days after the burst).

#T0+[day]  MID-UT    T-EXP[sec]   g'   g'_err Rc    Rc_err Ic    Ic_err
-----------------------------------------------------------------------
1.16123    11:40:06    1440.0    18.4   0.2   17.9   0.1   17.7   0.1
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

Ishigakijima Astronomical Observatory:
The observation started on 2013-04-28 14:02:08 UT (~1.26 days after the burst).
#T0+[day]  MID-UT    T-EXP[sec]   g'   g'_err  Rc   Rc_err  Ic   Ic_err
-----------------------------------------------------------------------
1.31290    15:18:30    1020.0    18.61 0.06   18.22 0.04   17.37 0.05
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130427B
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14499
SUBJECT: GRB 130427B: MITSuME Ishigakijima upper limits
DATE:    13/04/29 06:41:41 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda (OAO, NAOJ),  H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427B (Maselli et al., GCNC 14460)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

The observation started on 2013-04-28 18:47:24 UT (~1.23 days after the burst).
We did not find any new point source within the enhanced XRT circle
(Osborne et al., GCNC 14467) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
1.25418    19:26:42    3540.0   >20.6  >20.7  >20.1
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB100728A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14500
SUBJECT: GRB 100728A: GROND host detection and X-shooter redshift
DATE:    13/04/29 11:32:33 GMT
FROM:    Thomas Kruehler at Dark Cosmology Center  <tom@dark-cosmology.dk>

T. Kruehler (DARK), J. Greiner (MPE) and D. A. Kann (TLS) report:

We performed deep observations of the field of GRB 100728A
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405). GRB 100728A triggered Swift (Cannizzo et al.,
GCN 11004), GBM (von Kienlin, GCN 11006), Konus-Wind (Golenetskii
et al., GCN 11021) and Suzaku WAM (Tsai et al., GCN 11037).

Our late observations were performed on 2010-11-10, 105 days
after the trigger, and consisted of dithered images with a total of
4427 s exposure in g'r'i'z' and 3600 s in JHK under clear sky
conditions and a seeing of 0.8".

Inside the enhanced X-ray error-circle
(http://www.swift.ac.uk/xrt_positions), we detect an extended
object with an r'-band AB magnitude of r' = 25.0 +/- 0.2.

Its barycentric coordinates are:

RA (J2000) = 05:55:01.98
Dec. (J2000) = -15:15:19.7

with uncertainties of 0.3" in each coordinate.
Registering the early afterglow images (Olivares et al., GCN 11020)
against the late host frame, we derive an offset between galaxy
center and afterglow of approximately 0.4".

A spectrum of this galaxy was taken on 2012-11-15 with the ESO VLT
UT2 equipped with the X-shooter spectrograph, covering the
wavelength range 3000-25000 AA. The seeing was 1.2" and the
total exposure of our spectrum was 2400 s. In the VIS and NIR arm,
we detect emission lines, which we interpret as being due to
[O II](3729) and Halpha at a common redshift of z = 1.567.

The bright X-ray emission (Evans et al., GCN 11014), coupled with the
faint and red optical/NIR afterglow (Olivares et al., GCN 11020) is
characteristic of dust-extinguished events. Fitting the available
afterglow data with synchrotron models, the visual extinction along
the GRB sightline is constrained to 1.5 mag < A_V < 3 mag at z = 1.567.


GRB_name: GRB130425A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14501
SUBJECT: GRB 130425: MASTER-Net optical observations
DATE:    13/04/29 12:59:52 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

H. Levato and C. Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

C. Mallamaci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA)

E. Gorbovskoy, V. Lipunov,  V. Kornilov, D. Denisenko, A. Kuznetsov,
D. Kuvshinov, A. Belinski, N. Tyurina, N. Shatskiy, P. Balanutsa, D. 
Zimnukhov, V.V. Chazov
Lomonosov Moscow State University, Sternberg Astronomical Institute

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V. Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

K. Ivanov, S. Yazev, N.M. Budnev, O. Gres, O. Chuvalaev, V.A. Poleshchuk
Irkutsk State University

V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

V. Krushinski, I. Zalozhnich,  A. Popov, A. Bourdanov, A. Punanova
Ural Federal University

MASTER-ICATE robotic very wide field cameras (FOV=2x384 square degrees,
D=72mm, f/1.2, 1 pix = 22 arcsec, http://observ.pereplet.ru) located
in Argentina (Observatorio Astronomico Felix Aguilar,
http://master.sai.msu.ru:8080/) were pointed to the
GRB 130425A (von Kienlin, GCN 14442, K. Hurley et. al GCN 14446, S. 
Golenetskii et. al 14447) 40 sec after FERMI trigger Time  at 2013-04-25 
07:52:08 UT. We cover full IPN error box (K. Hurley et. al GCN 14446).

We haven't found optical transient within IPN error box on our 5-s
frames and on the coadded image made of 60 frames and total exposure of 
300 seconds. The 3-sigma upper limit (with the reference to V magnitudes 
from Tycho-2 catalog) has been about 11.0 mag on single images and 13.0 
mag on coadded image.

The coverage map available here:
http://master.sai.msu.ru/static/MASTER_ARG_GRB130425A_single.jpeg

The reduction of the whole data set is continuing.
This message can be cited.


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14502
SUBJECT: GRB 130427A: Improved Swift-XRT analysis
DATE:    13/04/29 14:32:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, K.L. Page (U. Leicester), A. Maselli, V. Mangano, M. Capalbi 
(INAF-IASFPA), D.N. Burrows (PSU) report on behalf of the Swift-XRT team:

We have reanalysed the XRT data for GRB 130427A (Maselli  et al. GCN 
Circ. 14448) from 144 s to 141 ks  after the BAT trigger. The data 
comprise 1.9 ks of  Windowed Timing (WT) mode data, with the rest taken 
in Photon Counting (PC) mode.

The star trackers on Swift failed to find a correct aspect solution 
during the first 1.9 ks of exposure (when the WT mode data were 
collected; see GCN Circ. 14448), and the GRB is seen to be drifting on 
the XRT detector. We have fitted this drift as a linear function, which 
is a good representation to the data. We have then rebuilt the GRB light 
curve and spectrum using this information. However, the time-tag of 
individual photon events may be incorrect by up to 1 second, and the 
method that we have used to correct the attitude may introduce low-level 
fluctuations. It is therefore inappropriate to perform any detailed 
timing or periodicity analysis with the current XRT data. We are working 
to rectify this situation.

The light curve can be modelled as a broken power-law with an initial 
decay index of 2.81 (+/- 0.04) with a break at T+421 s to a slope of 
alpha=1.17 (+/-0.01). This then breaks again at T+53.4ks to a final 
slope of 1.79 (+0.5, -0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed 
power-law with a photon spectral index of 1.91 (+/-0.11). The best 
fitting absorption column is 2.8 (+/-0.05) x 10^21 cm^-2 at a redshift 
of 0.34, in addition to the Galactic value of 1.8 x 10^20 cm^-2 
(Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV 
flux conversion factor deduced from this spectrum  is 3.8 x 10^-11 (5.2 
x 10^-11) erg cm^-2 count^-1.

If the light curve continues to decay with a power-law decay index of 
1.79, the count rate at T+3 days will be 0.14 count/sec, corresponding 
to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x 10^-12 (7.3 x 
10^-12) erg cm^-2 s^-1.

The automated light curve of this GRB is online at 
http://www.swift.ac.uk/xrt_curves/00554620/


This circular is an official product of the Swift-XRT team.


GRB_name: GRB130427A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14503
SUBJECT: GRB 130427A in the Ep,i - Eiso plane
DATE:    13/04/29 17:09:35 GMT
FROM:    Lorenzo Amati at INAF-IASF/Bologna  <amati@iasfbo.inaf.it>

L. Amati (INAF - IASF Bologna, Italy), S. Dichiara, F. Frontera, C. 
Guidorzi (University of Ferrara, Italy), report:

Based on the preliminary values of fluence and spectral parameters 
reported by the Fermi/GBM (Kienlin et al., GCN 14473) and Konus-Wind 
(Golenetskii et al., GCN 14487) teams, and by assuming a redshift of 0.34 
(Levan et al., CGN 14455; Flores et al., GCN 14491) and a standard 
Lambda_CDM cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_Lambda 
= 0.73, we estimate for GRB 130427A an intrinsic spectral peak energy Ep,i 
of 1250+/-150 keV and an isotropic-equivalent radiated energy of 
(1.05+/-0.15)x10^54 erg (1-10000 keV cosmological rest-frame).

These values are fully consistent with the best-fit power-law of the 
Ep,i-Eiso correlation holding for all long-bright cosmological GRBs (as 
determined, e.g., by Amati et al. 2009, A&A 508, 173). This is further 
evidence that the prompt emission properties of GRB 130427A, the most 
energetic GRB detected at z < 1, are the same as those of very bright, 
high-redshift events. Hence, its relatively low redshift makes it a unique 
case for investigating wether this class of events is associated to SNe 
with properties similar to those associated to "local" sub-luminous GRBs.


GRB_name: GRB130418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14504
SUBJECT: GRB 130418A: Bassano Bresciano Observatory lightcurve analisis
DATE:    13/04/29 17:30:35 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs  <oabb@ulisse.bs.it>

U.Quadri, L.Strabla, R.Girelli and A.Quadri 
report:

Photometric optical measurements of GRB 130418A detected by SWIFT trigger 553847 
(de Pasquale et al. 2013; GCN Circ. 14377) have been done using the Schmidt 
telescope 0.32m F/3.1 and Starlight CCD camera HX-516 applied at direct focus. 
120 sec. exposure time and 2x2 binning were used for all photos. 
All exposure were unfiltered. 
Flat field and dark have been captured and all images were corrected with them. 
Astrometrica software version 4.6.5.390 was used to perform differential photometry on 
the reduced images. 

began of period: 2013/04/18.80415 -  17 min after  the burst.
end   of period: 2013/04/18.92338 - 188 min after  the burst.


The photometric results as follow:

------------------------------------
Date UTC             Mag.   1 sigma.
------------------------------------
 
2013 04 18.80485    15.68    0.08
2013 04 18.80846    16.12    0.13
2013 04 18.82000    16.44    0.10
2013 04 18.90014    17.64    0.08
2013 04 18.85910    17.21    0.13
2013 04 18.87354    17.39    0.12
2013 04 18.88799    17.53    0.09
2013 04 18.90968    17.74    0.09

------------------------------------

Magnitudes were estimated with the USNO-B1 cat. 
and are not corrected for galactic dust extinction.

Images and analisis are available at the following address:

http://www.osservatoriobassano.org/archivio/grb/GRB130418A-Trig-553847-2013-04-18.htm

This message may be cited.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14505
SUBJECT: GRB 130427A: CrAO RT-22 36 GHz observation
DATE:    13/04/29 20:35:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volvach (CrAO), L. Volvach (CrAO), A. Pozanenko (IKI) on behalf of 
larger  collaboration report:

We observed the field of GRB 130427A (Maselli et al., GCN 14448) on Apr. 
28 between (UT) 16:22-18:41 with 22-m radio telescope RT-22 of
Crimean Astrophysical Observatory at mean frequency of 36 GHz. At the 
position of  the optical (Elenin et al., GCN 14450; Perley et al., GCN 
14451) and radio afterglow (Zauderer et al., GCN 14480; Zauderer et al., 
GCN 14482; Perley, GCN 14494) we detected a source with a flux 1.9 Â± 0.4 
mJy  at T_mid = 1.405 days after burst trigger.


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14506
SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations
DATE:    13/04/29 20:41:58 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We again observed the field of GRB 130427A (Maselli, et al., GCN 14448)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico
Nacional on Sierra San Pedro Mrtir from 2013/04 29.14 to 2013/04 29.27 UTC
(43.64 to 46.60 hours after the BAT trigger), obtaining a total of 3.02
hours exposure in the r' and i' bands and 1.57 hours exposure in the Z, Y,
J, and H bands.

We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450)
in all bands.  In comparison with SDSS DR8 and 2MASS, we find:

  r'    18.90 +/- 0.01
  i'    18.67 +/- 0.01
  Z     18.38 +/- 0.03
  Y     18.19 +/- 0.02
  J     18.29 +/- 0.02
  H     18.01 +/- 0.02

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertaints are 1-sigma.  The
source has faded by about 1 magnitude in all bands as compared to our
measurements on the previous night (Butler et al. 2013; GCN 14483).

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14507
SUBJECT: GRB 130427A: SARA-N detection
DATE:    13/04/29 21:18:59 GMT
FROM:    Dieter Hartmann at Clemson.U  <hdieter@clemson.edu>

William C. Keel (U. of Alabama, Tuscaloosa), Dieter Hartmann and Aman Kaur
(Clemson University) report:

We observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the
SARA 0.9m telescope at KPNO  (http://saraobservatory.org) from 0350-0420 UT
on April 29, obtaining a total of 30 min exposure in the B,V, and R band.

We detect the optical afterglow (Elenin et al; GCN14450) in all bands.
In comparison with Landolt (PG 0942) standard stars we find

B = 19.32
V = 19.00
R = 18.53

These magnitudes are not corrected for Galactic extinction, but include
KPNO airmass corrections at the time of observation.

This message may be cited


GRB_name: GRB130427A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14508
SUBJECT: GRB 130427A: Fermi-LAT refined analysis
DATE:    13/04/29 21:30:22 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin@nasa.gov>

S. Zhu, J. Racusin (NASA/GSFC), J. Chiang (SLAC), G. Vianello (Stanford) report on behalf of the Fermi LAT team:

Using LAT source class events >100 MeV between T0+0 and 700 seconds after the GBM trigger, we find a LAT localization of RA = 173.148, Dec = +27.709, with a 68% containment radius of 0.068 degrees (statistical only). This localization is consistent with other reported positions.

The >100 MeV emission spectrum during the GBM T90 (T0+0 to 138 seconds) is fit by a power law with an index of -1.96 +/- 0.07. The fluence during this time is (1.1 +/- 0.1)E-4 erg/cm^2, making this the highest fluence LAT-detected burst in the LAT energy range (Fermi LAT Collaboration, arXiv:1303.2908). The >100 MeV peak flux, measured from 11.52 to 37.33 seconds, is (1.4 +/- 0.2)E-3 ph/cm^2/s.

The LAT Low Energy (LLE) emission during the bright structured peak (0 to 20 seconds) is roughly correlated with the GBM emission. A spike at T0+0 seconds is coincident in both LAT and LLE, but precedes the onset of the GBM emission. There are peaks in the LAT light curve at approximately 13 and 22 seconds; neither peak is coincident with the LLE or GBM.

Significant emission >100 MeV was detected throughout the first orbit until ~735 seconds, at which point the burst became occulted by the Earth. The LAT emission was still significantly detected when the burst emerged from occultation at ~3000 seconds, and remained detectable for about a day. The extended emission light curve can be fit by a broken power-law that has a power-law index = -0.89 +/- 0.04 at early times, and at late times, it has an index in the range -1.3 to -1.5; the temporal break occurs around 550-800 seconds after the GBM trigger.

We clarify that the Swift-BAT trigger time (Barthelmy et al., GCN 14470) is ~51 seconds after the GBM trigger, so the emission detected by RAPTOR beginning ~50 seconds before the Swift trigger with a peak magnitude of R~7.4 (Wren et al., GCN 14476) is therefore coincident with the GBM and LAT emission onset.

The Fermi LAT point of contact for this burst is Sylvia Zhu (s.jc.zhu@gmail.com).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14509
SUBJECT: GRB 130427A: further GMG observations
DATE:    13/04/29 22:59:58 GMT
FROM:    Xiao-hong Zhao at Yunnan Obs  <zhaoxiaohong78@gmail.com>

X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J. G. Wang(YNAO), J.-M. Bai 
(YNAO) report on behalf of a larger collaboration:

We further observed the afterglow of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope on Apr 28 and Apr 29. 
The sloan filter of r' was used. The magnitudes of the afterglow are 
r'~18.2  31.16 hrs after trigger
r'~18.9  53.37 hrs after trigger 

We thank the GMG staff, especially Hong-Yan Gao, Jian-Duo He and Gui-Hua He for performing these observations.


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14510
SUBJECT: GRB 130427A: Continued Skynet/PROMPT Observations
DATE:    13/04/30 01:26:11 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, T. Berger, H. T. 
Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. 
Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:

Skynet continued observing the Swift/XRT localization of GRB 130427A 
(Maselli et al., GCN 14448, Swift trigger #554620) with four 16" 
telescopes of the PROMPT array at CTIO, Chile, starting at 2013-04-28, 
23:06 UT, and continuing until 04-29, 3:51 UT (t=39.28h-44.03h 
post-trigger). It took ~110 160-s exposures, simultaneously in each of 
the BVRI bands. We performed photometry on each exposure, calibrated to 
two SDSS stars in the field. B-band photometry was performed on stacks 
of 3-4 images in order to provide at least 3sigma detections.

A preliminary light curve of the second's data is at:
http://skynet.unc.edu/grb/grb130427a_2.png

A light curve of both the first and second nights' data is at:
http://skynet.unc.edu/grb/grb130427a_1_2.png

See Trotter et al. (GCN 14497) for a description of the first night's 
observations.  Further Skynet observations are ongoing.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14511
SUBJECT: GRB 130427A: Challis Observatory optical observations
DATE:    13/04/30 03:59:05 GMT
FROM:    Jay Norris at Boise State U.  <jnorris@custertel.net>

Jay Norris, Daryl Macomb (Boise State U.) report:

We observed GRB 130427A with the Challis Observatory's 0.4-m telescope
(114.33 deg W, 44.5 deg N, 2165 m elevation) on April 29, 05:58 to 06:22 UT.
Using seventeen 10-second frames in the R filter acquired in a clear sky,
centered at ~ 06:06 UT, 22.3 hours after the Swift/BAT trigger (GCN 14448),
we clearly detected the optical afterglow.

Comparison with six stars in the field of view (R = 15.5 to 16.8 mag)
yielded an estimate of R = 17.6 mag for the afterglow with uncertainty
of ~ 0.15 mag.  Further observations were interrupted by clouds.

[GCN OPS NOTE(30apr13): Per author's request, the affiliation in the FROM-line
was changed to Boise State U.]


GRB_name: GRB130427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14513
SUBJECT: GRB 130427A: MITSuME Ishigakijima Optical Observation after 2 days
DATE:    13/04/30 14:33:12 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda (OAO, NAOJ),  H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427A (Masell et al., GCNC 14448)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

We detected the previously reported afterglow (Elenin et al., GCNC 14450)
in all the three bands. The observation started on 2013-04-29 15:02:55 UT (~2.30
days after the burst).

Photometric results of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'   g'_err  Rc   Rc_err  Ic   Ic_err
-----------------------------------------------------------------------
2.31262    15:18:06   1500.0     19.19 0.05   18.87 0.04   18.65 0.09
2.33383    15:48:38   1440.0     19.29 0.06   18.90 0.05   18.76 0.11
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14514
SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations
DATE:    13/04/30 14:42:55 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We again observed the field of GRB 130427A (Maselli, et al., GCN 14448)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico
Nacional on Sierra San Pedro Mrtir from 2013/04 30.14 to 2013/04 30.37 UTC
(67.58 to 73.15 hours after the BAT trigger), obtaining a total of 3.91
hours exposure in the r' and i' bands and 1.64 hours exposure in the Z, Y,
J, and H bands.

We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450)
in all bands.  In comparison with SDSS DR8 and 2MASS, we find:

  r'    19.39 +/- 0.01
  i'    19.31 +/- 0.01
  Z     18.89 +/- 0.03
  Y     18.75 +/- 0.03
  J     18.87 +/- 0.02
  H     18.56 +/- 0.03

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.  Uncertaints are 1-sigma.  The
source has faded by about 0.5 magnitude in all bands as compared to our
measurements on the previous night (Butler et al. 2013; GCN 14506).

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14515
SUBJECT: GRB 130427A: high energy gamma-ray detection by AGILE
DATE:    13/04/30 15:57:24 GMT
FROM:    Francesco Verrecchia at ASDC  <francesco.verrecchia@asdc.asi.it>

=========================================================================
F. Verrecchia, C. Pittori (ASDC and INAF/OAR), A. Giuliani (INAF/IASF-Mi),
M. Marisaldi (INAF/IASF-Bo), F. Longo (University of Trieste and INFN
Trieste), F. Lucarelli (ASDC and INAF/OAR), E. Del Monte, F. Lazzarotto, I.
Donnarumma, Y. Evangelista, M. Feroci, L. Pacciani, P. Soffitta, E. Costa,
I. Lapshov, M. Rapisarda (INAF/IAPS Rome), G. Barbiellini, (INFN Trieste),
A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, V.
Fioretti, F. Fuschino, M. Galli (INAF/IASF-Bo), A. Chen, S. Mereghetti,
F. Perotti, P. Caraveo (INAF/IASF-Mi), M. Cardillo, E. Striani, M. Tavani
(INAF/IAPS Rome, and Univ. Roma Tor Vergata), A. Argan, G. Piano, S.
Sabatini, V. Vittorini (INAF/IAPS Rome), G. Pucella (ENEA Frascati), A.
Pellizzoni, A. Trois (INAF/OA Cagliari), M. Pilia (ASTRON), S. Vercellone
(INAF/IASF-Pa), P. W. Cattaneo, A. Rappoldi (INFN Pavia), A. Morselli, P.
Picozza (INFN Roma-2), M. Prest, E. Vallazza (Universita' 
dell'Insubria), P.
Lipari, D. Zanello (INFN Roma-1), P. Giommi (ASI), and G. Valentini (ASI),
on behalf of the AGILE Team, report:

The AGILE Gamma Ray Imaging Detector (GRID) detected high energy emission
from GRB 130427A (A. Maselli et al., GCN 14448), also reported
by Fermi-LAT (S. Zhu et al., GCN 14471).
A preliminary analysis of the AGILE-GRID data in temporal coincidence with
the GRB shows a significant excess of gamma-ray photons above 50 MeV at the
location of the event. The emission detected by the AGILE-GRID mostly
occurred between ~ t0 + 180 sec and t0 + 700 sec where t0 is 27 April 2013
at 07:47:15 UT. During this interval, the burst position was inside the
instrument FOV.

A maximum likelihood analysis of the AGILE-GRID data integrating over 12
hours, from 2013-04-27 05:00 UT to 2013-04-27 17:00 UT, using the standard
parameters used by AGILE quick look to detect persistent gamma-ray sources,
yields a detection at a significance level larger than 6 sigma, and a mean
flux F = (8.0+/-2.7) 10-6 ph/cm2/s (E > 100 MeV).
The preliminary photon spectral index obtained with this integration is
1.55 +/- 0.30.
Due to the exceptionally high fluence above 100 MeV of this burst, it is
possible for the first time to derive its properties using the maximum
likelihood techniques routinely used in the standard data analysis of
AGILE-GRID point sources.

The GRB also triggered the AGILE Minicalorimeter (MCAL), sensitive to
gamma-rays above 350 keV, at the time 07:47:06 UT.
According to the MCAL light curve, the emission lasts for about 20 s 
divided
into three main episodes. Although the large initial off-axis angle (more
than 120 degrees) prevents an accurate spectral analysis of MCAL data,
significant emission above 15 MeV is detected.

This measurement was obtained with AGILE observing a large portion of the
sky in spinning mode.

This message may be cited.
=========================================================================


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14516
SUBJECT: GRB 130427A: photo-z of possible SDSS host galaxy
DATE:    13/04/30 16:59:55 GMT
FROM:    Alina Volnova at SAI MSU  <alinusss@gmail.com>

A. Vonova (IKI), L. Elenin (KIAM), A. Pozanenko (IKI)

We have investigated photo-z of possible host galaxy (Melandri et al., GCN
14452, Levan et al., 14455). Using LePhare sw (Arnouts et al. 1999, MNRAS,
310, 540; Ilbert et al. 2006, A&A, 457, 841) and SDSS  magnitudes  we
estimated a redshift of the galaxy z = 0.49 (+0.12,-0.24). This photo-z
value is compatible with a spectroscopy redshift (Levan et al., GCN 14455;
Xu et al., GCN 14478; Flores et al., 14491) and  confirms the SDSS galaxy
as the host.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14517
SUBJECT: GRB 130427A: Nishi-Harima Optical Spectroscopic Observations
DATE:    13/04/30 18:06:47 GMT
FROM:    Akira Arai at Nishi-Harima Astro._Obs/U_of_Hyogo  <arai@nhao.jp>

A. Arai, J. Takahashi, K. Morihana, S. Honda and Y. Takagi (Univ. of Hyogo)
report on behalf of Nayuta team:

We performed low resolution ( R ~ 500) optical spectroscopic observations
of a source on the position of GRB 130427A (Masell et al., GCNC 14448)
with MALLS attached to the Nayuta 2-m telescope at the Nishi-Harima
Astronomical Observatory.

The observations were conducted from 2013-04-27 12:48 UT to 2013-04-27
22 : 09 UT (from ~5.1 h to ~ 5.4 h after the burst).

The resulting spectrum ( S/N ~ 5) shows a feature less continuum light
without any emission nor absorption line features in the wavelength
range between 450 nm and 680 nm.

[GCN OPS NOTE(30apr13): Per operator, I have corrected a mistake I made 
in assigning the affiliation for this submitor.]


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14518
SUBJECT: GRB 130427A: Continued GMG optical observations
DATE:    13/04/30 23:02:28 GMT
FROM:    Xiao-hong Zhao at Yunnan Obs  <zhaoxiaohong78@gmail.com>

X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), L. Chang (YNAO), J.-M. Bai 
(YNAO) report on behalf of a larger collaboration:

We again observed the afterglow of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope from 15:46:37 UT on 2013-04-30. 
We used the sloan filter of r' and obtained two images with the exposure time of 900s each image. The GRB afterglow decayed to r'~19.4 with a middle time of
80.2 hrs post-burst. 

We thank the GMG staff, especially Jian-Duo He and Gui-Hua He for performing these observations.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14519
SUBJECT: GRB 130427A: GMRT radio detection
DATE:    13/05/01 08:20:09 GMT
FROM:    Poonam Chandra at TIFR  <poonam@ncra.tifr.res.in>

Poonam Chandra (NCRA-TIFR) reports on behalf of a larger team:

We carried out Giant Metrewave Radio Telescope (GMRT) observations of
GRB 130427A at 1390 GHz band on 2013 Apr 30.57 UT. In our preliminary
analysis we detect the GRB with a flux density of 500+/-94 uJy at
RA, Decl (J200) of 11 32 32.81, +27 41 56.00 which is consistent with
optical position reported by Elenin et al. (GCN 14450) within error bars.

We thank GMRT staff for making these observations possible. More
observations are planned.


GRB_name: GRB130427A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14520
SUBJECT: GRB 130427A: High-energy neutrino search
DATE:    13/05/01 14:09:45 GMT
FROM:    Erik Blaufuss at U. Maryland/IceCube  <blaufuss@icecube.umd.edu>

Search for high-energy neutrinos in coincidence with GRB 130427A

The IceCube collaboration (icecube.wisc.edu) reports:

We used the data from IceCube to perform several searches for high-energy neutrinos in spatial and temporal 
coincidence with GRB 130427A (A. Maselli et al., GCN 14485). 

The first analysis is an automated online search for muon neutrino multiplets of two or more neutrinos in coincidence
within 100 seconds and 3.5 degrees. The search has a threshold of ~1 TeV and does not depend on an external GRB
trigger. No such multiplet was found. 

A second offline analysis is a likelihood based search for muon neutrinos with energies ~1 TeV and higher, with a primary 
background of atmospheric neutrinos and atmospheric muons. Data was scanned in the T90=162.83 s window reported by Swift BAT (S. D. 
Barthelmy et al., GCN 14470), and found no neutrinos.  We also performed a series of rolling time-window searches 
covering a window of interest of +/- 1 hour relative to the burst time and again found no neutrinos.

A final search focused on  neutrinos of all flavors with energies ~100 TeV and higher that have interaction vertices that fall within the detector in a window 
of interest of +-1 day. Because the intrinsic background for this search is very low only temporal information was used 
in this search. No neutrinos were found in this search.

Implications with respect to neutrino fluence for this GRB will be reported elsewhere. 

IceCube is a kilometer cubed neutrino telescope located at the geographic South Pole sensitive to neutrinos above 
~100 GeV. Previous limits on the emission of neutrinos by GRBs have been presented in R. Abbasi et al., Nature 484, 
351354 (2012). A description of the multiplet search is found in R. Abbasi et al., A&A 539, A60 (2012). Funding 
acknowledgement and author list for IceCube are listed [http://icecube.wisc.edu/collaboration/authors/current here]


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14521
SUBJECT: GRB 130427A: ABT optical observations
DATE:    13/05/01 14:15:39 GMT
FROM:    Klaas Wiersema at U Leicester  <kw113@leicester.ac.uk>

I. van de Stadt (AWSV Metius, the Netherlands), K. Wiersema (U. of Leicester),
T. Bekkers (AWSV Metius), M. Seynen (AWSV Metius) and
F. Nieuwenhout (AWSV Metius) report:

We observed the afterglow of GRB 130427A with the ABT, a 10-inch remote controlled observatory in Alkmaar,
The Netherlands. In a series of V band exposures the afterglow is detected with
V=18.70 +/- 0.13 mag at midtime 1.633 days after burst.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14522
SUBJECT: GRB 130427A: VLA 20 GHz detection
DATE:    13/05/01 14:19:24 GMT
FROM:    Alessandra Corsi at GWU  <corsi@email.gwu.edu>

A. Corsi (GWU) reports on behalf of a larger collaboration:
 
We imaged the position of GRB 130427A (Maselli et al., GCN 14448) with
the Very Large Array in the 20-22 GHz frequency band, starting at about
1.9 days after the burst. A provisional reduction shows a source consistent
with the location of the GRB optical (e.g., Elenin et al., GCN 14450; Perley et al.,
GCN 14451) and radio (e.g., Zauderer et al., GCN 14480) afterglow. At this time
and frequency (~21 GHz), we estimate a preliminary flux of about 1.3 mJy.
 
Further observations are planned.
We thank the VLA staff for their support.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14523
SUBJECT: GRB 130427A: SARA-N optical observations
DATE:    13/05/01 20:29:14 GMT
FROM:    Dieter Hartmann at Clemson.U  <hdieter@clemson.edu>

Aman Kaur, Dieter Hartmann (Clemson University), and William C. Keel (U.
of Alabama, Tuscaloosa),  report:

We continued our observations of GRB 130427A (Maselli, et al., GCN 14448) 
with the SARA 0.9m telescope at KPNO  (http://saraobservatory.org)
starting on April 29. We obtained a total of 190 min exposure in the R
band, with a sequence of 36 five min exposures,  and one ten  min
exposure.

We detect the optical afterglow (Elenin et al; GCN14450) decay between  R
= 19.2 and R = 19.4
during that sequence, which implies a temporal power law decay of the flux
density with a slope of
alpha ~ 0.8

Magnitudes are not corrected for Galactic extinction.

This message may be cited


GRB_name: GRB130425A
Detection_method: Suzaku WAM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14524
SUBJECT: GRB 130425A: Suzaku WAM observation of the prompt emission
DATE:    13/05/02 04:34:53 GMT
FROM:    Norisuke Ohmori at Miyazaki U  <ohmori@astro.miyazaki-u.ac.jp>

M. Akiyama, M. Yamauchi, N. Ohmori (Univ. of Miyazaki),
M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa
(Hiroshima U.),
M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida, H. Ueno, S. Sugimoto (Saitama U.),
K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun,
T. Takahashi (ISAS/JAXA), W. Iwakiri(RIKEN), Y. Hanabata (ICRR), Y. Urata
(NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku
WAM team, report:

The long GRB 130425A (Fermi-GBM detection: von Kienlin, GCN 14442;
IPN localization: Hurley et al., GCN14446) triggered by the 
Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of
50 keV - 5 MeV at 07:51:22.243 UT (=T0).

The observed light curve shows a weak initial single peak from T0-2s to 
T0-1s and multi-peaked structure starting from T0+30s from T0+61s,
with a duration (T90) of about 61 seconds.
The fluence in 100 - 1000 keV was 2.74(+0.12/-0.18) x 10^-5^  erg/cm^2^ .
The 1-s peak flux measured from T0+37s was 6.51(+0.96/-1.26) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from T0-2s to
T0+61s is well fitted by a single power-law with a photon index of
2.41 (+0.19/-0.17) (chi^2/d.o.f = 14.7/14).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curves for this burst will be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14525
SUBJECT: GRB 130427A: KAIT optical observations
DATE:    13/05/02 07:17:53 GMT
FROM:    Weikang Zheng at U.of Michigan  <zwk@umich.edu>

WeiKang Zheng, S. Bradley Cenko, Alexei V. Filippenko and Adam Morgan
(UC Berkeley) report on behalf of the KAIT GRB team:

We observed the afterglow of GRB 130427A (e.g., Maselli et al., GCN
14448; Elenin et al., GCN 14450; Perley, GCN 14451) with the 0.76-m
Katzman Automatic Imaging Telescope (KAIT) located at Lick Observatory
on Apr. 28, 29, 30, and May 1 UT. Observations were carried out in the
B, V, R, and I filters. A series of images, lasting for about an hour,
was taken on each night. The afterglow is well detected in all filters,
and the estimated R-band magnitudes (calibrated to SDSS, transformed to
R) are as follows, with times relative to the BAT trigger:

t_mid(hr) exp(s) R(mag) err

20.2 60.0 17.4 +/- 0.1
45.1 60.0 18.5 +/- 0.1
69.1 360.0 19.1 +/- 0.1
93.1 600.0 19.6 +/- 0.2

A power-law fit to the data shows the afterglow continues to decay with
an index of roughly -1.0 (Itoh et al., GCN 14486).

Further observations are planned.


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14526
SUBJECT: GRB 130427A: Predictions about the occurrence of a supernova
DATE:    13/05/02 09:15:09 GMT
FROM:    Remo Rufinni at ICRA  <ruffini@icra.it>

R. Ruffini, C.L. Bianco, M. Enderli, M. Muccino, A.V. Penacchioni, G.B. Pisani, J.A. Rueda, N. Sahakyan, Y. Wang, L. Izzo report:

The late x ray observations of GRB 130427A by Swift-XRT clearly evidence a pattern typical of a family of GRBs associated to supernova (SN) following the Induce Gravitational Collapse (IGC) paradigm (Rueda & Ruffini 2012; Pisani et al. 2013). We assume that the luminosity of the possible SN associated to GRB 130427A would be the one of 1998bw, as found in the IGC sample described in Pisani et al. 2013. Assuming the intergalactic absorption in the I-band (which corresponds to the R-band rest-frame) and the intrinsic one, assuming a Milky Way type for the host galaxy, we obtain a magnitude expected for the peak of the SN of I = 22 - 23 occurring 13-15 days after the GRB trigger, namely between the 10th and the 12th of May 2013.

Further optical and radio observations are encouraged.


GRB_name: GRB130502A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14527
SUBJECT: GRB 130502A: Swift detection of a burst
DATE:    13/05/02 18:07:57 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

E. Troja (NASA/GSFC/UMCP), A. A. Breeveld (UCL-MSSL),
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
S. T. Holland (STScI), H. A. Krimm (CRESST/GSFC/USRA),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU),
M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. C. Stroh (PSU),
C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the
Swift Team:

At 17:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130502A (trigger=554996).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 138.578, -0.143 which is 
   RA(J2000) = 09h 14m 19s
   Dec(J2000) = -00d 08' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 5 sec.  The rapidly available light
curve also shows a peak in the lowest energy at T+10 sec, but it is
not clear at this time whether or not the second peak is real. The 
peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after 
the trigger. 

The XRT began observing the field at 17:52:01.8 UT, 91.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 138.5690, -0.1232 which
is equivalent to:
   RA(J2000)  = 09h 14m 16.56s
   Dec(J2000) = -00d 07' 23.7"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 78 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.49 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5
(+1.77/-1.57) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 95 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.03. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130502A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14528
SUBJECT: GRB 130502A: T100 Observations
DATE:    13/05/02 19:42:53 GMT
FROM:    Tolga Guver at UA  <tolga@physics.arizona.edu>

T.  Guver  (Sabanci  Univ.),  B.  Ozcan  (Adiyaman  Univ.)  E.  Sonbas
(Adiyaman  Univ.),   M.  Kocak   (TUG),  E.  Gogus   (Sabanci  Univ.),
H. Kirbiyik (TUG) report on behalf of a larger collaboration

We observed  the field of Swift  GRB 130502A (Troja  et al. GCN#14527)
with  the  1.0 meter  T100  telescope  (TUBITAK National  Observatory,
Antalya - Turkey),  starting May, 02, 18:17:41 UT  (~ 27 minutes after
the trigger). Observations were carried out in the R filter under good
weather conditions.

We do  not detect an optical  afterglow within the  reported XRT error
circle down to  a limiting magnitude of 20.8 in the  R band. Our image
is calibrated  using USNO A2.0 R1 magnitude of the star at  RA :
135.578498, DEC : -00.149362 (J2000).

We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their technical support.

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GRB_name: GRB130502A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14529
SUBJECT: GRB 130502A: T100 Observations
DATE:    13/05/02 19:43:10 GMT
FROM:    Tolga Guver at UA  <tolga@physics.arizona.edu>

T.  Guver  (Sabanci  Univ.),  B.  Ozcan  (Adiyaman  Univ.)  E.  Sonbas
(Adiyaman  Univ.),   M.  Kocak   (TUG),  E.  Gogus   (Sabanci  Univ.),
H. Kirbiyik (TUG) report on behalf of a larger collaboration

We observed  the field of Swift  GRB 130502A (Troja  et al. GCN#14527)
with  the  1.0 meter  T100  telescope  (TUBITAK National  Observatory,
Antalya - Turkey),  starting May, 02, 18:17:41 UT  (~ 27 minutes after
the trigger). Observations were carried out in the R filter under good
weather conditions.

We do  not detect an optical  afterglow within the  reported XRT error
circle down to  a limiting magnitude of 20.8 in the  R band. Our image
is calibrated  using USNO A2.0 R1 magnitude of the star at  RA :
135.578498, DEC : -00.149362 (J2000).

We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their technical support.

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GRB_name: GRB130502B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14530
SUBJECT: GRB 130502B: Fermi GBM detection of a burst
DATE:    13/05/02 20:15:24 GMT
FROM:    George A. Younes at USRA/NASA/MSFC  <younes.ge@gmail.com>

A. Von Kienlin (MPE) and G. Younes (NASA/USRA) report on behalf of the Fermi GBM Team:

"At 07:51:11.76 UT on May 2 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130502B (trigger 389173874 / 130502327).

The on-ground calculated location, using the GBM trigger
data, is RA = 74.5, DEC = 70.6 (J2000 degrees), with an uncertainty
of 1.0 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 47 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of multiple spikes
with a duration (T90) of about 24 s (50-300 keV).
The time-averaged spectrum from T0-4.1 s to T0+71.7 s is
best fit by a Band function with Epeak = 323.00 +/- 7.00 keV,
alpha = -0.75 +/- 0.01, and beta = -2.47 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(1.21 +/- 0.01)E-04 erg/cm^2. The 1.024 sec peak photon flux
measured starting from T0+30.3 s in the 8-1000 keV band
is 45.8 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

[GCN OPS NOTE(02may13):  The "April" in the first sentence was changed to "May".]


GRB_name: GRB130502A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14531
SUBJECT: GRB 130502A: TNG candidate counterpart
DATE:    13/05/02 21:37:53 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), P. D'Avanzo (INAF/OABr), M. Cecconi (INAF/FGG), 
C. P. Padilla-Torres (INAF/FGG), report on behalf of the CIBO collaboration:

We observed the field of GRB 130502A (Troja et al., GCN 14527) with the 
TNG equipped with DOLoRes. A 10-minute image in the SDSS r filer was 
taken starting on May 2.872 UT (3.08 hr after the GRB trigger).

Close to the edge of the current XRT error circle (see 
http://www.swift.ac.uk/xrt_positions/), we detect a faint object, with 
coordinates (J2000):

RA = 09:14:16.42
Dec = -00:07:23.0

The object has r = 23.49 +- 0.16 AB, calibrated against nearby SDSS DR8 
stars.

At the present time, we cannot assess the variability of the target, nor 
its relation with GRB 130502A. Further observations are planned.


GRB_name: GRB130502B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14532
SUBJECT: GRB 130502B: Fermi LAT Detection
DATE:    13/05/02 21:50:17 GMT
FROM:    Daniel Kocevski at SLAC  <dankocevski@gmail.com>

GRB 130502B: Fermi-LAT detection of a burst

D. Kocevski (NASA/GSFC), G. Vianello (Stanford), J. Chiang (SLAC), J. Racusin (NASA/GSFC), and E. Troja (CRESST) report on behalf of the Fermi-LAT team:

At 07:51:11 UT on 2nd May 2013, Fermi-LAT detected high energy emission from GRB 130502B, which was also detected by Fermi-GBM (trigger 389173874/130502327) (GCN 14530) .

The best LAT on-ground location is found to be RA, DEC 66.648, 71.0841 (J2000) with an error radius of 0.093 deg (68% containment, statistical error only), this was about ~45 deg from the LAT boresight at the time of the trigger. The data from the Fermi-LAT show a multi-peaked light curve consistent with the GBM data. More than 100 photons above 100 MeV are observed within 200 seconds with a TS of > 158. The multi-peak structure is clearly seen in the non-standard LAT Low Energy (LLE) data selection, with a significance of ~8 sigma. The highest energy LAT photon consistent with the burst position has an energy of 30 GeV and arrived ~220s after the trigger.

A Swift TOO request has been submitted.

The Fermi LAT point of contact for this burst is Daniel Kocevski (daniel.kocevski@nasa.gov).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB130502A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14533
SUBJECT: GRB 130502A: z-band observations from GTC
DATE:    13/05/02 22:23:16 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J. Gorosabel (UPV/EHU, IAA-CSIC), 
N. Tanvir (U. Leicester), J. P. U. Fynbo (DARK/NBI), A. Cabrera-Lavers (IAC-ULL), 
and C.C. Thoene (IAA-CSIC) report:

We observed the afterglow of GRB 130502A (Troja et al. GCN 14527) 
with the 10.4m GTC telescope starting at 21:01 UT (3.18 hrs after the burst). 
The observation had a total exposure time of 340 s in z-band. The object 
reported by Malesani et al. GCN 14531 is detected with an AB magnitude of 
22.6+/-0.15 as compared to stars in the SDSS DR9 catalogue.


GRB_name: GRB130427A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14534
SUBJECT: GRB 130427A: MITSuME Ishigakijima Optical Observation after 5 days
DATE:    13/05/03 00:10:46 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda (OAO, NAOJ),  H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130427A (Masell et al., GCNC 14448)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

We detected the previously reported afterglow (Elenin et al., GCNC 14450)
in only Rc-band. The observation started on 2013-05-02 13:08:42 UT
(~5.2 days after the burst).

Photometric result and three sigma upper limits of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'   Rc   Rc_err  Ic
---------------------------------------------------------
5.25248    13:51:30    540.0    >20.7  20.3 0.3   >19.1
---------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130502A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14535
SUBJECT: GRB 130502A: OSN and IAC80 I-band observations
DATE:    13/05/03 00:16:29 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu@iaa.es>

J. Gorosabel (IAA-CSIC/UPV-EHU), A. de Ugarte Postigo (IAA-CSIC/DARK-NBI),
J.C. Tello (IAA-CSIC),  A.J. Castro-Tirado (IAA-CSIC), J. Cepa (IAC), D.
Jimenez-Mejias (IAC), R. Alonso (IAC), R. Sanchez-Ramirez (IAA-CSIC), V.
Casanova (IAA-CSIC), report on behalf of a larger collaboration:

We observed the GRB 130502A (Troja et al. GCN 14527) optical afterglow
(Malesani et al. GCN 14531; de Ugarte Postigo et al. GCN 14533) in I-band
with both the 1.5m OSN and 0.82m IAC80 telescopes as follows;

  Tel.  Hr post-GRB  Texp  Vega(Mag)
 -------------------------------------
 OSN    3.13-3.71  10x200s  > 22.0
 IAC80  3.43-5.14  16x300s 22.75+/-0.35
 -------------------------------------

calibrated against the USNO B1.0 catalogue.


GRB_name: GRB130502A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14536
SUBJECT: GRB 130502A: Enhanced Swift-XRT position
DATE:    13/05/03 00:24:15 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 511 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130502A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 138.56888, -0.12341 which is equivalent
to:

RA (J2000): 09h 14m 16.53s
Dec (J2000): -00d 07' 24.3"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14537
SUBJECT: GRB 130418A: TNG NIR observations
DATE:    13/05/03 02:14:30 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, M. Cecconi, C. P. Padilla-Torres (INAF/TNG) report on behalf
of the CIBO collaboration:

We observed the field of GRB 130418A (De Pasquale et al., GCN 14377) with
the TNG telescope located in the Canary Islands. We obtained a set of
J-band images with the NICS camera on May 1.891 (mean observing time;
about 13.1 days from the GRB).

No source is detected at the optical afterglow position (De Pasquale et
al. GCN 14377; Gorosabel et al. GCN 14378; Quadri et al. 14379; Kuin et
al., GCN 14384; Hentunen et al., GCN 14394) down to a 3sigma limiting
magnitude of J~21.3 (calibrated against the 2MASS catalogue).


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14538
SUBJECT: GRB 130427A: Pan-STARRS 1 optical observations
DATE:    13/05/03 04:00:34 GMT
FROM:    Heather Flewelling at IfA/Hawaii  <flewelling.heather@gmail.com>

H. Flewelling, A. Schultz, N. Primak, K. C. Chambers, E. A. Magnier, W.
Sweeney, C. Z. Waters, S. Chastel, M. E. Huber, I. Smith, report on behalf
of Pan-STARRS 1:

Pan-STARRS 1, a 1.8 m survey telescope located at Haleakala, Hawaii,
observed GRB 130427A (Masell et al., GCNC 14448) a total of 4 times in the
z and y filters using the 1.4 Gigapixel camera, in the course of normal
survey operations. PS1 detected the afterglow (Elenin et al., GCNC 14450),
and the observations were calibrated with the "ubercal" technique (Schafly
et al 2011) and the PS1 reference catalog (Magnier et al 2012). The results
are:

t_mid(hr) exp(s) filter      mag
108.18    80.0    y      19.52 +/- 0.10
108.21    80.0    y      19.66 +/- 0.09
111.35    60.0    z      19.84 +/- 0.07
111.37    60.0    z      19.81 +/- 0.06

Note the host galaxy pre-outburst has been observed in the PS1 3pi survey
and thus photometry of the host galaxy is available.

This discovery was made possible by the PS1 system operated by the
 PS1 Science Consortium and its member institutions (
http://www.ps1sc.org/PS1_System_GCN.shtml ). We thank the telescope
 operators of the PS1 telescope for their support.


GRB_name: GRB130502A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14539
SUBJECT: GRB 130502A: RATIR Optical and NIR Observations
DATE:    13/05/03 06:08:32 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130502A (Troja, et al., GCN 14527) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/05 3.14 to 2013/05 3.17 UTC (9.48 to
10.34 hours after the BAT trigger), obtaining a total of 0.71 hours
exposure in the r' and i' bands and 0.30 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Beardmore, et al., GCN
14536), in comparison with SDSS DR8 and 2MASS, we obtain the following
upper limits (3-sigma):

  r'    > 22.82
  i'    > 22.66
  Z    > 21.65
  Y    > 21.45
  J    > 21.16
  H    > 20.99

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130502B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14540
SUBJECT: GRB 130502B Swift-XRT observations 
DATE:    13/05/03 13:17:58 GMT
FROM:    Stefan Immler at NASA/GSFC  <stefan.m.immler@nasa.gov>

A. Melandri (INAF-OAB) and S. Immler (NASA/CRESST/GSFC) report on behalf of the Swift-XRT team:

We have analysed 3.4 ks of XRT data for the Fermi/LAT-detected burst:
GRB 130502B,  from 55.1 ks to 67.9 ks after the  Fermi/LAT trigger. The
data are entirely in Photon Counting (PC) mode.  An X-ray source is
detected within the Fermi/LAT error circle. Using 3614 s of PC mode
data and 6 UVOT images, we find an enhanced XRT position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue): RA, Dec = 66.76207, +71.06071 which is equivalent to:

RA (J2000): 04h 27m 02.90s
Dec(J2000): +71d 03' 38.5"

with an uncertainty of 1.5 arcsec (radius, 90% confidence). This
position is 157 arcsec from the Fermi/LAT position.  The light curve is
consistent with a constant source of mean count rate 1.1e-01 ct/sec. A
power-law fit gives an index of 0.8 (+/-1.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.88 (+0.28, -0.26). The
best-fitting absorption column is  2.8 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.3 x 10^-11 (6.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.8 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 3.1 sigma
Photon index:      1.88 (+0.28, -0.26)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020266.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130502B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14541
SUBJECT: GRB 130502B: P60 Observations
DATE:    13/05/03 13:48:50 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>

S. B. Cenko (UC Berkeley), D. A. Perley, and L. P. Singer (Caltech) report
on behalf of a larger collaboration:

We imaged the field of the Fermi GBM (Von Kienlin et al., GCN 14530) and
LAT (Kocevski et al., GCN 14532) GRB130502B with the robotic Palomar 60
inch telescope.  Observations began at 03:34 UT on 3 May 2013 (~ 0.82 d
after the GBM trigger) and were obtained under poor seeing conditions.  We
detect no significant emission at the position of the candidate X-ray
afterglow (Melandri et al., GCN 14540).  Using nearby point sources from
the USNO-B1 catalog for reference, we measure an upper limit of r' > 20.4
mag at this time.


GRB_name: GRB130502B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14542
SUBJECT: Konus-Wind observation of GRB 130502B
DATE:    13/05/03 14:32:02 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration intense GRB 130502B
(Fermi-GBM detection: von Kienlin et al., GCN 14530;
Fermi-LAT detection: Kocevski et al., GCN 14532)
triggered Konus-Wind at T0=28272.763s UT (07:51:12.763)

The light curve shows a bright multi-peaked structure
from ~T0 s to ~T0+30s.
The emission is seen up to 10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130502_T28272/

As observed by Konus-Wind, the burst
had a fluence of (1.13  0.04)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+29.944s,
of (1.81  0.08)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+27.392 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.84  0.04,
the high energy photon index beta = -2.7  0.1,
the peak energy Ep = 293  9 keV,
chi2 = 107/91 dof.

The spectrum at the maximum count rate
(measured from T0+26.624 to T0+27.392 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.81  0.06,
the peak energy Ep = 264  14 keV,
chi2 = 104/93 dof.

All the quoted results are preliminary.


GRB_name: GRB130502A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14543
SUBJECT: GRB 130502A: Swift/UVOT Upper Limits
DATE:    13/05/03 15:08:05 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (MSSL-UCL) and E. Troja (NASA/GSFC/UMCP) report on behalf 
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130502A 96 
s after the BAT trigger (Troja et al., GCN Circ. 14527).
An optical afterglow consistent with the position of the TNG candidate 
(Malesani et al. GCN Circ. 14531) is detected in the initial white 
exposure. Preliminary magnitude and 3-sigma upper limits using the UVOT 
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for 
the first white finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)    Exp(s)     Mag

white_FC         96         246          147        20.90  0.3
white           588         608           20        >20.06
u               309         559          246        >20.6
b               564         584           20        >19.25
v              5288        5488          197        >19.81
uvw1           5698        5898          197        >20.16
uvm2           5492        5692          197        >19.96

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.03 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB130502B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14544
SUBJECT: GRB 130502B: Swift/UVOT Upper Limits
DATE:    13/05/03 15:09:16 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (MSSL-UCL) and S. Immler (NASA/CRESST/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130502B 
55101 s after the LAT trigger (Kocevski et al., GCN Circ. 14532). No 
optical afterglow consistent with the refined XRT position (Melandri et 
al., GCN Circ. 14540) is detected in the UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system 
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial 
exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC         55101        55208          105         >20.3
white            55101        89746         4493         >22.1

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.21 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB130502A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14545
SUBJECT: GRB 130502A: Fermi GBM detection
DATE:    13/05/03 17:11:22 GMT
FROM:    George A. Younes at USRA/NASA/MSFC  <younes.ge@gmail.com>

G. Younes (NASA/USRA) reports on behalf of the Fermi GBM Team:

"At 17:50:30.74 UT on May 2 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130502A (trigger 389209833 / 130502743),
which was also detected by the Swift/BAT (Troja et al. 2013, GCN 14527).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 20 degrees from Swift location.

The GBM light curve consists of a single pulse with a FRED-like shape
with a duration (T90) of about 3 s (50-300 keV).
The time-averaged spectrum from T0-0.384 s to T0+2.880 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.0 +/- 0.3 and
the cutoff energy, parameterized as Epeak, is 83 +/- 17 keV.

The event fluence (10-1000 keV) in this time interval is
(5.0 +/- 0.6)E-07 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0-0.064 s in the 8-1000 keV band
is 7 +/- 1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130502B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14546
SUBJECT: IPN Triangulation of GRB 130502B
DATE:    13/05/03 19:38:51 GMT
FROM:    Kevin Hurley at UCBerkeley/SSL  <khurley@ssl.berkeley.edu>

K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team, 

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, 
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

D. M. Smith, on behalf of the RHESSI GRB team, 

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of
the Swift-BAT team,

E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, I. Lapshov,
F. Lazzarotto, and M. Marisaldi, on behalf of the AGILE Team, and

V. Connaughton, M. S. Briggs, C. Meegan, and V. Pelassa, 
on behalf of the Fermi GBM team, report:

GRB 130502B (von Kienlin et al., GCN 14530, Kocevski et al., GCN 14532,
Golenetskii et al., GCN 14542) has been observed by AGILE MCAL, Fermi
GBM, INTEGRAL (SPI-ACS), Konus-Wind, MESSENGER (GRNS), RHESSI, Suzaku
WAM, and Swift BAT (outside the coded field of view), so far.  We have
triangulated it to a long, narrow error box which reduces the
size of the LAT (statistical-only) error circle (GCN 14532) and produces 
the following error box:


              RA(2000)                                  DEC(2000)

CENTER:  66.6391 deg = 04 h 26 m 33 s         71.0809 deg = 71 d 04 ' 51 "
CORNERS: 66.8800 deg = 04 h 27 m 31 s         71.0295 deg = 71 d 01 ' 46 "
         66.4487 deg = 04 h 25 m 48 s         71.1511 deg = 71 d 09 ' 04 "
         66.8267 deg = 04 h 27 m 18 s         71.0114 deg = 71 d 00 ' 41 "
         66.4008 deg = 04 h 25 m 36 s         71.1314 deg = 71 d 07 ' 53 "

The area of this box is about 17 square arcminutes, and it contains the
Swift-XRT source (Melandri et al., GCN 14540).  Maps have been posted at
ssl.berkeley.edu/ipn3/130502

The triangulation can be improved.


GRB_name: GRB130502A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14547
SUBJECT: GRB 130502A: Swift-XRT refined Analysis
DATE:    13/05/03 20:29:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.C. Stroh (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C.
Pagani (U. Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti
(INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), J.A. Kennea
(PSU) and E. Troja report on behalf of the Swift-XRT team:

We have analysed 2.3 ks of XRT data for GRB 130502A (Troja  et al. GCN
Circ. 14527),  from 76 s to 16.0 ks after the  BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.68 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+/-0.3). The
best-fitting absorption column is  1.6 (+0.8, -0.7) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.4 x 10^-11 (5.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 3.2 sigma
Photon index:      2.2 (+/-0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00554996.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130502A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14548
SUBJECT: GRB130502A: MASTER-Net optical observations
DATE:    13/05/03 21:26:20 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, 
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko, A.Sankovich
Sternberg Astronomical Institute, Moscow State University

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB130502A 55 sec  after notice 
time and 266 sec after GRB time at 2013-05-02 17:54:56.337 UT in two 
polarizations. On our first (50s exposure) set we haven't found optical transient  within SWIFT 
error-box (E. Troja et. al. GCN 14527).
The 5-sigma upper limit has been about 18.5 mag
The message may be cited.


GRB_name: GRB130427A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14549
SUBJECT: GRB 130427A: Non-observation of VHE emission with HAWC
DATE:    13/05/04 01:24:00 GMT
FROM:    Dirk Lennarz at HAWC  <dirk.lennarz@gatech.edu>

D. Lennarz, I. Taboada (Georgia Tech) report on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration/):

We used data from the partially built HAWC detector to perform a search
for VHE emission in temporal coincidence with GRB 130427A (A. Maselli et
al., GCN 14448). This search was conducted using the scaler data
acquisition only, as the main data acquisition was not operational at
the time. At the time of the GBM trigger, the elevation of the burst in
HAWC's field of view, was only 33.13 degrees and setting. The
sensitivity of HAWC at this elevation is more than 2 orders of magnitude
poorer than near the zenith. Furthermore, while near zenith the nominal
threshold of the scaler system is a few GeV, towards the horizon the
nominal threshold is much higher.

We used six search windows with respect to the GBM trigger time: one in
the range 0 s to 20 s, which covers the bright structured peak seen by
Fermi-GBM that seems to be correlated with the Fermi-LAT emission (S.
Zhu et al., GCN 14508), an extended window from -5 s to 55 s and a
window from -5 s to 145 s, which is slightly larger than the T90
reported by GBM. We also searched around the second peak in the GBM
light curve (120 s to 300 s), -10 s to 10 s around the time of the
highest energy LAT photon and in an extended window from -10 s to 290 s.
We find a deviation of +38960 / -77884 / -337877 / -165991 / -519485 /
-1036 of the global PMT count with respect to a moving average in the
six time windows mentioned above. The p-value for these deviations
assuming background hypothesis are 17 % / 78 % / 95 % / 71 % / 90 % and
50 % respectively. Our observations are consistent with background only.

The implications of this non-detection with respect to the VHE fluence
of this GRB will be reported elsewhere.

HAWC is a gamma-ray detector under construction in Central Mexico. It
currently consists of 29 operational Water Cherenkov Detectors out of
300 planned. A detailed description of the sensitivity of HAWC to GRBs
can be found in A.U. Abeysekara et al., Astroparticle Physics 35,
641-Â–650 (2012).


GRB_name: GRB130502A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14550
SUBJECT: GRB 130502A: Swift-BAT refined analysis
DATE:    13/05/04 01:58:01 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), A. Y. Lien (NASA/GSFC/ORAU),
T. Sakamoto (AGU), C. B. Markwardt (GSFC), W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU),
E. Troja (NASA/GSFC/UMCP), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130502A (trigger #554996)
(Troja, et al., GCN Circ. 14527).  The BAT ground-calculated position is
RA, Dec = 138.579, -0.134 deg, which is
   RA(J2000)  =  09h 14m 19.1s
   Dec(J2000) = -00d 08' 04.2"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 47%.

The mask-weighted light curve consists a single FRED pulse starting at
~T-0.3 sec, peaking at ~T+0.1 sec, and returning to baseline at ~T+4 sec.
T90 (15-350 keV) is 3.0 +- 0.3 sec (estimated error including systematics).

The time-averaged spectrum from T-0.19 to T+3.20 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.78 +- 0.16.  The fluence in the 15-150 keV band is 3.8 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.21 sec in the 15-150 keV band
is 2.9 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/554996/BA/


GRB_name: GRB130502B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14552
SUBJECT: GRB 130502B: possible TNG counterpart
DATE:    13/05/04 09:19:10 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), P. D'Avanzo (INAF/OABr), S. Covino (INAF/OABr), 
A. Melandri (INAF/OABr), V. D'Elia (INAF/OAR and ASI/ASDC), S. Campana 
(INAF/OABr), D. Fugazza (INAF/OABr), G. Tagliaferri (INAF/OABr), B. Blu, 
L. Di Fabrizio (INAF/FGG), C. P. Padilla-Torres (INAF/FGG), report on 
behalf of the CIBO collaboration:

We observed the field of the LAT-detected GRB 130502B (Von Kienlin & 
Younes, GCN 14530; Kocevski et al., GCN 14532; Golenetskii et al., GCN 
14542) with the TNG equipped with the DOLoRes imager. Observations were 
carried out starting on 2013 May 3.872 UT (1.54 days after the trigger), 
for a total of 30 min on source in the R band, at a high airmass of 
around 2.2. The seeing was 1.2".

No bright object is detected inside the X-ray error circle (Melandri & 
Immler, GCN 14540; see also http://www.swift.ac.uk/xrt_positions/), down 
to a 3-sigma limit of R = 23.7 (calibration based on several nearby USNO 
stars). However, a faint flux enhancement is seen consistent with the 
XRT position, at coordinates (J2000):

RA = 04:27:02.82
Dec = +71:03:38.5

A finding chart is shown at 
http://www.astro.ku.dk/~malesani/GRB/130502B/GRB130502B_finder.jpg

We estimate the magnitude of this marginally detected source to be R = 
24.7 +- 0.5. At the moment, we have no information about its 
variability, and it could be either the GRB counterpart or its host galaxy.

Last, independently of the reality of the object, this GRB can be 
classified as dark. Considering the limit R > 23.7, and a Galactic 
extinction A_V = 0.57 (Schlafly & Finkbeiner 2011, ApJ, 737, 103), the 
optical-to-X-ray spectral index is beta_OX < 0.47 (if the object is 
real, then beta_OX = 0.34 +- 0.07). The presence of significant excess 
column density in the X-ray spectrum (Melandri & Immler, GCN 14540; see 
also http://www.swift.ac.uk/xrt_spectra/00020266/) suggests an 
extinguished event.

[GCN OPS NOTE(04may13): Per author's request, the URL in the last paragraph
was change from the team-internal version to the public version.]


GRB_name: GRB130504A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14553
SUBJECT: Swift-XRT X-ray afterglow candidate for GRB 130504A (BAT trigger 555096)
DATE:    13/05/04 09:28:24 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB), K.L. Page (U.
Leicester), P.A. Evans (U. Leicester)  report on behalf of the
Swift-XRT team:

We have analysed 654 s of XRT data for GRB 130504A,  from 99 s to 754 s
after the  BAT trigger. The data are entirely in Photon Counting (PC)
mode.

No X-ray afterglow is detected within the BAT error circle (Cummings et
al. GCN 14551). We note however the presence of a bright, uncatalogued,
fading X-ray source at the following refined position RA, Dec =
272.45484, -16.31423 which is equivalent to:

RA (J2000): 18 09 49.16
Dec(J2000): -16 18 51.2

with an uncertainty of 3.5 arcsec (radius, 90% confidence). This
position is about 5.5 arc min away from the BAT position. Given its
fading nature, we propose it as the X-ray afterglow of GRB 130504A.

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.79 (+/-0.19).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+/-0.4). The
best-fitting absorption column is  1.6 (+0.5, -0.4) x 10^22 cm^-2, in
excess of the Galactic value of 8.1 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 7.4 x 10^-11 (1.3 x 10^-10) erg
cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column:    1.6 (+0.5, -0.4) x 10^22 cm^-2
Galactic foreground:      8.1 x 10^21 cm^-2
Excess significance:      2.8 sigma
Photon index:    1.7 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
0.79, the count rate at T+24 hours will be 0.021 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x
10^-12 (2.8 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555096.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130504A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14554
SUBJECT: GRB 130504A, Swift-BAT refined analysis
DATE:    13/05/04 11:08:22 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC),
T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
  
Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130504A (trigger #555096)
(Cummings, et al., GCN Circ. 14551).  The BAT ground-calculated position is
RA, Dec = 272.459, -16.320 deg which is
    RA(J2000)  =  18h 09m 50.1s
    Dec(J2000) = -16d 19' 13.1"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).  The
partial coding was 100%.

This position is 5.3 arcmin away from the automated flight position reported
in GCN circular# 14551.  The imaging interval selected onboard was not optimum.
The refined error circle includes the position of the XRT afterglow candidate
reported by D'Avanzo et al. in GCN circular# 14553, hence we believe that
fading x-ray source to be the correctly identified afterglow of GRB 130504A.

The mask-weighted light curve shows multiple weak peaks.  T90 (15-350 keV) is
50 +- 10 sec (estimated error including systematics).
  
The time-averaged spectrum from T-31.07 to T+36.84 sec is best fit by a power
law with an exponential cutoff.  This fit gives a photon index 0.52 +- 0.68,
and Epeak of 84.5 +- 47.6 keV (chi squared 82.16 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV band is
0.9 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.41 +- 0.15 (chi squared 88.43 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555096/BA/


GRB_name: GRB130502B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14555
SUBJECT: GRB 130502B: Swift-XRT refined Analysis
DATE:    13/05/04 13:30:51 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri (INAF-OAB) and S. Immler (NASA/CRESST/GSFC) report on  
behalf of the Swift-XRT team:

We have analysed  8.3 ks of XRT data for the Fermi/LAT-detected burst:  
GRB 130502B (Kocevski  et al. GCN Circ. 14532), from 55.1 ks to 101.8  
ks after the Fermi/LAT trigger.

The object dectected in the first 3.4 ks of XRT data (Melandri &  
Immler GCN Circ. 14540) is now clearly fading. The light curve can be  
modelled with  a power-law decay with a decay index of alpha=1.52  
(+/-0.25).

A spectrum formed from the PC mode data can be fitted with an absorbed  
power-law with a photon spectral index of 1.89 (+/-0.20). The best- 
fitting absorption column is  1.73 (+0.78, -0.71) x 10^21 cm^-2, in  
addition to the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al.  
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion  
factor deduced from this spectrum  is 4.3 x 10^-11 (6.3 x 10^-11) erg  
cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Galactic foreground:    1.1 x 10^21 cm^-2
Intrinsic column:         1.73 (+0.78, -0.71) x 10^20 cm^-2
Photon index:          1.89 (+0.21, -0.20)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020266.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130504A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14556
SUBJECT: GRB 130504A: Swift/UVOT Upper Limits
DATE:    13/05/04 13:46:27 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (MSSL-UCL) and J. R. Cummings (GSFC/UMBC) report on 
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130504A 
89s after the BAT trigger (Cummings et al., GCN Circ. 14551), but the 
GRB position is outside the field of view for several exposures. No 
optical afterglow consistent with the XRT position (D'Avanzo et al. GCN 
Circ. 14553) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system 
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the u filter 
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               301          551          246         >19.8
white              858         1008          147         >20.5
w1                 680         6058          333         >20.2
m2                 655         7093          356         >20.4
w2                 606         6878          549         >20.8

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 3.22 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB130502B
Detection_method: Suzaku WAM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14557
SUBJECT: GRB 130502B: Suzaku WAM observation of the prompt emission
DATE:    13/05/04 15:15:48 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro@phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno,
S. Sugimoto (Saitama U.), M. Ohno, K. Takaki, T. Kawano,
R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.),
M. Yamauchi, N. Ohmori, M. Akiyama (Univ. of Miyazaki),
K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.),
Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA),
W. Iwakiri(RIKEN), Y. Hanabata (ICRR),
Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo)
on behalf of the Suzaku WAM team, report:

The bright, long GRB 130502B (Fermi-GBM detection : von Kienlin and
Younes, GCN 14530; Fermi-LAT detection : Kocevski et al., GCN 14532)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 07:51:15.113 UT (=T0).

The observed light curve shows a multi-peaked structure starting at
T0-2 s, ending at T0+34 s with a duration (T90) of about 24 seconds.
The fluence in 100 - 1000 keV was 7.38 (+0.37/-0.29) x10-5 erg/cm^2.
The 1-s peak flux measured from T0+22 s was
14.53 (-0.77/+0.73) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-2 s to T0+34 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -1.04 (+0.49/-0.36),
the high-energy photon index beta: -2.73 (+0.10/-0.12),
and the peak energy Epeak: 359 (+22/-33) keV (chi^2/d.o.f = 65.7/50).

Due to the high flux of this burst, a 3% systematic error was added
for low energy channels.
All the errors are quoted at 90% confidence level.

The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html


GRB_name: GRB130504A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14558
SUBJECT: GRB 130504A: Enhanced XRT position
DATE:    13/05/04 16:47:01 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo (INAF-OAB), P.A. Evans and M.R. Goad (U. Leicester) report on
behalf of the Swift-XRT team:

Using 3463 s of XRT Photon Counting mode data and 5 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
272.45604, -16.31339 which is equivalent to:

RA (J2000):  18 09 49.45
Dec (J2000): -16 18 48.2

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received.  The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130504A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14559
SUBJECT: GRB 130504A: Bassano Bresciano Observatory optical upper limit
DATE:    13/05/04 17:23:59 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs  <oabb@ulisse.bs.it>

U.Quadri, L.Strabla, R.Girelli and A.Quadri report:

We imaged the field of GRB 130504A detected 
by SWIFT(trigger 555096) with the robotic 
telescopes of (IAU station 565) Bassano Bresciano 
Observatory, Italy.

The observations started automatically 2 min 42 sec after the 
GRB trigger, with our schmidt telescope D=400 mm F/D=3 
and our Newton telescope D=250mm F/D=5.5.

Weather conditions were good.

We co-added 2 series of 10 unfiltered CCD exposures of 120s each.

We did not found any optical counterpart in the error box of 
the XRTcandidate (Cummings et al. GCN 14551) and in error box of
X-ray afterglow candidate (P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB)
et al. GCN 14553) at our following limiting magnitude:
.

Start      End       Vlim
2.7min     52min     18.0


Magnitudes were estimated with the USNO-B1 cat. 
and are not corrected for galactic dust extinction.

The message may be cited.


GRB_name: GRB130504B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14560
SUBJECT: GRB 130504B: Fermi GBM detection
DATE:    13/05/04 19:49:10 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 07:32:03.39 UT on 04 May 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130504B (trigger 389345526/ 130504314).

The on-ground calculated location, using the GBM trigger
data, is RA = 353.5, DEC = -5.6 (J2000 degrees, equivalent to 23 h 34 m, -05
d 34'),
with an uncertainty of 1 degree (radius, 1-sigma containment, statistical
only; 
there is additionally a systematic error which is currently estimated to be
2 to 3 degrees).

The angle from the Fermi LAT boresight is 57 degrees. Moreover, this 
burst was bright enough to result in a Fermi spacecraft autonomous 
rapid repoint (ARR) maneuver. 

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of a single spike with a duration (T90) 
of about 0.4 s (50-300 keV). The time-averaged spectrum from T0-0.064 s 
to T0+0.448 s is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.42 +/- 0.04  and the 
cutoff energy, parameterized as Epeak, is 1300 (+80/-70)keV.

The event fluence (10-1000 keV) in this time interval is
(6.01 +/- 0.14)E-06 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0+0.32 s in the 10-1000 keV band
is 40 +/- 2 ph/s/cm^2.

A Band function fits the spectrum equally well with 
Epeak= 1300 +/-80 keV, alpha = -0.42 +/-0.04 
and beta = -3.4 (+0.4/-0.9).

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130504B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14561
SUBJECT: IPN Triangulation of GRB 130504B
DATE:    13/05/04 22:39:03 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,

V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on
behalf of the Swift-BAT team, report:

The short-duration, hard spectrum, intense GRB 130504B (von Kienlin et 
al., GCN Circ. 14560) has been observed by Fermi GBM, INTEGRAL 
(SPI-ACS), Konus-Wind, Swift (BAT), and MESSENGER (GRNS), so far, at 
about 27123 s UT (07:32:03). The burst was outside the coded field of 
view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   347.952 (23h 11m 49s)  -5.739 ( -5d 44' 20")
  Corners:
   347.658 (23h 10m 38s)  -5.056 ( -5d 03' 20")
   348.087 (23h 12m 21s)  -6.133 ( -6d 07' 58")
   348.256 (23h 13m 01s)  -6.420 ( -6d 25' 10")
   347.821 (23h 11m 17s)  -5.345 ( -5d 20' 41")
  ---------------------------------------------
The error box area is 196 sq. arcmin, and its maximum
dimension is 1.5 deg (the minimum one is 2.9 arcmin). The Sun distance 
was 57 deg.

This box can be improved.

The center of the GBM location (von Kienlin, GCN Circ. 14560) is 5.6
deg from the center of the IPN box.

A triangulation map will be posted at
http://www.ioffe.ru/LEA/GRBs/GRB130504_T27119/IPN/


GRB_name: GRB130504A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14562
SUBJECT: GRB 130504A: MITSuME Okayama upper limits
DATE:    13/05/05 02:16:31 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130504A (Cummings et al., GCNC 14551)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-05-04 15:09:24 UT (~13.1 h after the burst).
We did not find any new point source within the enhanced XRT circle
(D'Avanzo et al., GCNC 14558) in all the three bands.

Photometric results of the OT are listed below.
We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.58630    16:09:50    6360.0   >19.9  >19.7  >18.6
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130505A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14563
SUBJECT: GRB 130505A: Swift detection of a burst with optical afterglow
DATE:    13/05/05 08:36:39 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), P. T. O'Brien (U Leicester),
B. Sbarufatti (INAF-OAB/PSU) and M. Stamatikos (OSU/NASA/GSFC) report
on behalf of the Swift Team:

At 08:22:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130505A (trigger=555163).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 137.060, +17.485 which is 
   RA(J2000)  =  09h 08m 14s
   Dec(J2000) = +17d 29' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a bright peak
followed by a much weaker peak with a total duration of about 20 sec. 
The peak count rate was ~35,500 counts/sec (15-350 keV), at ~0 sec 
after the trigger. 

The XRT began observing the field at 08:24:04.7 UT, 96.4 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 137.0626, 17.4857 which is equivalent to:
   RA(J2000)  = +09h 08m 15.02s
   Dec(J2000) = +17d 29' 08.5"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 9.3 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 7.35e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 106 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 09:08:14.64 = 137.06100
  DEC(J2000) = +17:29:05.2  =  17.48479
with a 90%-confidence error radius of about 0.74 arc sec. This position is 6.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.14 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.04. 

Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130504A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14564
SUBJECT: GRB 130504A: IAC80 optical candidate
DATE:    13/05/05 08:38:59 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu@iaa.es>

J. Gorosabel (IAA-CSIC/UPV-EHU), A. de Ugarte Postigo (IAA-CSIC/DARK-NBI),
J.C. Tello (IAA-CSIC),  A.J. Castro-Tirado (IAA-CSIC), J. Cepa (IAC), D.
Jimenez-Mejias (IAC),  J.L. Doreste Caballero (HGT), D. Hernandez Ojados
(SECAT), R. Sanchez-Ramirez (IAA-CSIC),  report on behalf of a larger
collaboration:

We observed the GRB 130504A field (BAT trigger 555096; Cummings et al. GCN
14551) with the 0.82m IAC80 telescope. The data were acquired in the
I-band. The observations started at 02:22:30.6 UT (~17 min post burst) and
lasted ~1.5 hours.

An object, coincident with the enhanced XRT position (D'Avanzo et al.
14558), shows a clear fading in our images. The optical candidate is
placed at RA(J2000)=18:09:49.44, DEC(J2000)=-16:18:48.0 with a Vega
magnitude of I=18.1 (against USNO B1.0) in our first images.


GRB_name: GRB130504B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14565
SUBJECT: Konus-Wind observation of GRB 130504B
DATE:    13/05/05 09:20:24 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The short-duration hard GRB 130504B
(Fermi-GBM detection: von Kienlin, GCN 14560;
IPN triangulation: Golenetskii et al., GCN 14561)
triggered Konus-Wind at T0=27119.723s UT (07:31:59.723)

The light curve shows a double-peaked structure
from ~T0-0.064 s to ~T0+0.368s.
The total duration of the burst is ~0.430 s
The emission is seen up to ~8 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130504_T27119/

As observed by Konus-Wind, the burst
had a fluence of (9.3  0.9)x10-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.320s,
of (5.0  0.9)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.50  0.13,
the peak energy Ep = 980  125 keV,
chi2 = 40/36 dof.

All the quoted results are preliminary.


GRB_name: GRB130505A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14566
SUBJECT: GRB 130505A: MAXI/GSC detection
DATE:    13/05/05 10:13:07 GMT
FROM:    Satoshi Nakahira at JAXA/MAXI  <nakahira.satoshi@jaxa.jp>

GRB 130505A: MAXI/GSC detection

S. Nakahira (JAXA), M. Serino (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Nakano (AGU),
H. Tsunemi, M. Sasaki (Osaka U.),
M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro, (Kyoto U.),
Y. Tsuboi, M. Higa (Chuo U.),
M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.),
K. Yamaoka (Nagoya U.) report on behalf of the MAXI team

At 2013-05-05T08:22:29 UT, the MAXI/GSC detected an uncatalogued X-ray
transient source. Assuming that the source flux was constant over the
transit, we obtain the source position at
(R.A., Dec.) = (136.955 deg, 17.585 deg)= (09 07 49 , +17 35 05)(J2000)
with a 90% C.L. statistical error of 0.07 deg and an additional systematic
uncertainty of 0.1 deg (90% containment radius).

The position and time are consistent with those of GRB 130505A (Cannizzo
et al, GCN #14563). The transit by MAXI occurred from
2013-05-05T08:22:18 (=T0-10 s, where T0 is the Swift/BAT trigger time) to T0+40s.
The averaged X-ray flux was 3.17 +/- 0.21 Crab (2-20 keV).
The spectrum is fitted by a power-law model with a photon index of
1.37 (-0.10/+0.10). There was no significant excess flux at the previous
transit at 2013/05/05 06:46 UT and at the next transit at 2013/05/05
09:55 UT with an upper limit of 20 mCrab for each.


GRB_name: GRB130505A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14567
SUBJECT: GRB 130505A - Gemini-N/GMOS redshift determination
DATE:    13/05/05 10:30:19 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), T. Matulonis
and A. B. Smith (Gemini) report on behalf of a larger collaboration:

We observed the afterglow of GRB 130505A (Cannizzo et al. GCN 14563)
with the GMOS-N spectrograph on Gemini-N, beginning approximately 60 min
after the BAT trigger.

In our provisional reduction we detect numerous absorption lines, including
Lyman alpha, SiII/SiII*1260, SiII*1264, OI1302, SiII/OI*1304, SiII*1309,
CII/CII* 1334/1335, SiIV1394/1403, SiII 1527, SiII* 1533, CIV 1548/1551,
FeII 1608, AlII 1671 and AlIII 1855/1863 at a common redshift of z=2.27.

The presence of fine structure lines, in particular, confirms this to be the
redshift of this burst.


GRB_name: GRB130505A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14568
SUBJECT: GRB 130505A: MITSuME Okayama Optical Observation
DATE:    13/05/05 12:02:12 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130505A (Cannizzo et al., GCNC 14563)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-05-05 10:52:56 UT (~2.5 h after the burst).
We detected the previously reported afterglow (Cannizzo et al., GCNC 14563)
in all the three bands.

Photometric results of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'  g'_err   Rc  Rc_err   Ic  Ic_err
-----------------------------------------------------------------------
0.11507    11:08:09    1620.0    18.2  0.1    18.2  0.1    17.6  0.1
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130505A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14569
SUBJECT: GRB 130505A: Enhanced Swift-XRT position
DATE:    13/05/05 13:07:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1875 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 130505A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 137.06069, +17.48471 which is equivalent
to:

RA (J2000): 09h 08m 14.57s
Dec (J2000): +17d 29' 05.0"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130505A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14570
SUBJECT: GRB 130505A; Weihai optical observations
DATE:    13/05/05 13:43:31 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), C. Cao, S.-M. Hu, J.-M. Ai (SDU) report:

We observed the field of GRB 130505A (Cannizzo et al., GCN 14563) with
the 1m telescope located in Weihai, Shandong Province, China. We
obtained 2x600s frames in the solan r-filter with a mean time of
3.3724 hr after the BAT trigger.

The optical afterglow is clearly detected at the UVOT position with
r=18.4 +/- 0.1 mag, calibrated against the SDSS field.


GRB_name: GRB130505A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14571
SUBJECT: GRB 130505A:  Xinglong TNT optical observations
DATE:    13/05/05 14:32:29 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L. P. Xin, J. Y. Wei, Y. L. Qiu,  J. Wang, 
J. S. Deng, C. Wu, X. H. Han  report on behalf of EAFON team:

We began to observe the field of GRB 130505A  (Cannizzo, et al., GCN 14563)
using  80cm TNT telescope located at Xinglong observatory, China
at 12:25:39 UT on 2013-05-05.  We obtained several R-band images.  

The reported optical counterpart (Cannizzo, et al., GCN 14563) is detected in all images. 
A prelinary analysis shows that its brightness is decaying from R~18.05 to R~18.68 mag
during  4.05h and 4.85h after the trigger time. 
These magnitudes are calibrated with USNO B1.0 R2 stars, 

This message may be cited.


GRB_name: GRB130505A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14572
SUBJECT: GRB 130505A: iTelescope T12 optical observations
DATE:    13/05/05 15:03:03 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:

We have detected GRB 130505A optical afterglow at iTelescope 
observatory T12 (Siding Spring, Australia) Takahashi FSQ ED 
0.10m/5.0 astrograph and SBIG STL-11000M CCD. Five 
unfiltered images with 600 sec and 300 sec exposure time were made.

The afterglow was detected at following position RA 09:08:14.6 and
DEC +17:29:04.

The following magnitudes were obtained from the observations using
NOMAD1 1075-0205635 (R=14.240) as the comparison:

Tmid(sec)+T0    Filter          Exp. time        Mag          Mag err. 
2485                  unfiltered      600            16.78CR     0.06
3370                  unfiltered      3x300        17.15CR     0.02
5061                  unfiltered      600            17.45CR     0.08


GRB_name: GRB130505A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14573
SUBJECT: Swift/UVOT observations of GRB130505A
DATE:    13/05/05 16:28:36 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <m.depasquale@ucl.ac.uk>

M. De Pasquale (MSSL/UCL) and J. K. Cannizzo (NASA/UMBC) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130505A
107 s after the BAT trigger (Cannizzo et al., GCN Circ. 14563). A bright 
but
rapidly fading source is detected in the finding chart and initial exposures
within the XRT error circle (Evans et al., GCN Circ. 14569).

The preliminary UVOT position is:
   RA(J2000)  =    09:08:14.64 = 137.0610
   DEC(J2000) =   +17:29:05.2  = +17.48478
with a 90%-confidence error radius of about 0.5 arc sec.

Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the early exposures are:

Filter         T_start(s)   T_stop(s)    Exp(s)           Mag

white (FC)         107          256        147          14.14  0.05
white             3952         4151        197          17.96  0.07
v                 4362         4561        197          17.50  0.11
b                 3503         3946        197          17.71  0.08
u                  320          542        218          14.66  0.04
uvw1              4772         4971        197          19.28  0.29 (~3 
sigma)
uvm2              4567         4766        197          >19.6
uvw2              4158         4357        197          >19.9

The non-detection of the optical source in um2 and uw2 filters is
consistent with the redshift z=2.27 found by Tanvir et al (GCN Circ. 14567)

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction of
the burst (Schlegel et al. 1998).


GRB_name: GRB130504C
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14574
SUBJECT: GRB 130504C: Fermi-LAT detection of a burst
DATE:    13/05/05 16:40:11 GMT
FROM:    Daniel Kocevski at SLAC  <dankocevski@gmail.com>

D. Kocevski (NASA/GSFC), M. Ohno (Hiroshima U.), J. Racusin (NASA/GSFC), G. Vianello (Stanford), V. Vasileiou (LUPM), and E. Troja (CRESST) report on behalf of the Fermi-LAT team:

At 23:30:15 UT on 04 May 2013, Fermi LAT detected high energy emission from GRB 130504C, which was also detected by Fermi-GBM (trigger 389402940 / 130504979).  The GBM detection triggered an autonomous repoint of the spacecraft.

The best LAT on-ground location is found to be RA=91.715, DEC=3.846 (J2000) with an error radius of 0.155 deg (68% containment, statistical error only). 

The burst was about 40 deg from the LAT boresight at the time of the trigger and the spacecraft slew brought the source within the LAT field of view for the next 2200 seconds. The data from the Fermi LAT show long lasting emission with >70 photons above 100 MeV observed out to 1000s seconds with a TS of >70.  Multi-peaked emission lasting roughly 40 seconds can be seen using the non-standard LAT Low Energy (LLE) with a significance of ~26 sigma. The highest energy LAT photon has an energy of ~5 GeV arriving 251 seconds after the trigger.

A Swift TOO request has been submitted.

A GBM circular is forthcoming.

The Fermi LAT point of contact for this burst is Daniel Kocevski (daniel.kocevski@nasa.gov).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.





Daniel Kocevski
NASA Goddard Space Flight Center
www.kocevski.com
510.316.3208


GRB_name: GRB130505A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14575
SUBJECT: Konus-Wind observation of GRB 130505A
DATE:    13/05/05 19:19:22 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long very intense GRB 130505A (Swift-BAT trigger #555136:
Cannizzo et al., GCN 14564) triggered Konus-Wind (K-W)
at T0=30147.038s UT (08:22:27.038).

The K-W light curve shows a bright pulse with a duration of ~5s
followed by a weaker decaying emission out to ~T0+30s with
a slight increase in the count rate at ~T0+15s.
The emission is seen up to ~10 Mev.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130505_T30147/

As observed by Konus-Wind, the main phase of the burst had
a fluence of (3.13  0.06)x10^-4 erg/cm2 and a 64-ms peak flux,
measured from T0+2.496 s, of (6.9  0.3)x10^-5 erg/cm2/s
(both in the 20 - 1200 keV energy range).

The time-averaged spectrum (measured from T0 to T0+21.248 s)
is best fit in the 20 keV-15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.69  0.04,
the high energy photon index beta = -2.03  0.03,
the peak energy Ep = 631  31 keV,
chi2 = 113/92 dof.

The spectrum at the maximum count rate
(measured from T0+2.304 to T0+2.816 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.31  0.09,
the high energy photon index beta = -2.26  0.07,
the peak energy Ep = 604  49 keV,
chi2 = 105/90 dof.

Assuming z=2.27 (Tanvir et al., GCN 14567)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
the isotropic energy release E_iso is ~3.8x10^54 erg,
the peak luminosity (L_iso)_max is ~2.7x10^54 erg/s,
and the rest-frame peak energy Ep,i = 2030 keV

All the quoted errors are estimated at the 1 sigma confidence level.


GRB_name: GRB130505A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14576
SUBJECT: GRB 130505A: Largest E_iso ever measured
DATE:    13/05/05 20:03:36 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann (TLS Tautenburg), and S. Schulze (PUC, MCSS) report:

Using the energetics provided by the Konus-Wind detection (Golenetskii et
al. 2013, GCN 14575) of the extremely intense Swift GRB 130505A (Cannizzo
et al. 2013, GCN 14564), and employing k-correction (Bloom et al. 2003,
ApJ, 594, 674), we determine the isotropic energy release in the
bolometric band (rest-frame 1 keV - 10 MeV) to be (5.65 +/- 0.13) x 10^54
erg (log E_iso = 54.75 +/- 0.01).

The most isotropically energetic GRBs known so far (all in the rest-frame
bolometric band) are GRBs 990123, 080916C and 090323, for which log E_iso
~ 54.5 - 54.6 has been found (e.g., Kann et al. 2010, ApJ, 720, 1513).

This makes GRB 130505A the most energetic GRB known, and may indicate
either an ultra-luminous event or a high degree of collimation.

We additionally note that the nearby GRB 130427A (Maselli et al. 2013, GCN
14448; Golenetskii et al. 2013, GCN 14487) is also highly energetic, with
log E_iso,bol = 54.21 +/- 0.05, but this is about 3.5 times less than GRB
130505A.

This message may be cited.


GRB_name: GRB130505A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14577
SUBJECT: GRB 130505A: Swift-XRT refined Analysis
DATE:    13/05/05 20:36:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), G. Stratta (ASDC), P. D'Avanzo
(INAF-OAB), V. D'Elia (ASDC), J.A. Kennea (PSU), M.C. Stroh (PSU) and
J.K. Cannizzo report on behalf of the Swift-XRT team:

We have analysed 11 ks of XRT data for GRB 130505A (Cannizzo  et al.
GCN Circ. 14563),  from 102 s to 29.4 ks after the  BAT trigger. The
data comprise 503 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN. Circ 14569).

The late-time light curve (from T0+3.7 ks) can be modelled with  a
power-law decay with a decay index of alpha=1.06 (+0.03, -0.04).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.86 (+/-0.03). The
best-fitting absorption column is  10.0 (+/-0.7) x 10^20 cm^-2, in
excess of the Galactic value of 3.6 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.92 (+/-0.07) and a
best-fitting absorption column of 8.8 (+1.6, -1.5) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.8 x 10^-11 (4.7 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.8 (+1.6, -1.5) x 10^20 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: 5.6 sigma
Photon index:      1.92 (+/-0.07)

If the light curve continues to decay with a power-law decay index of
1.06, the count rate at T+24 hours will be 0.27 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-11 (1.3 x 10^-11) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555163.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130505A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14578
SUBJECT: GRB 130505A: correction to GCN 14575
DATE:    13/05/05 21:14:09 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, on behalf of the Konus-Wind team, reports:

We have found a typo in our GCN Circ. 14575 "Konus-Wind observation of GRB 130505A":
the correct energy range for the K-W energy fluence and peak flux estimations
for GRB 130505A is 20-10000 keV, not  "20 - 1200 keV", as mentioned.
The 20-10000 keV range is a standard for the K-W estimations of GRB energetics
in the observer frame.

We are sorry for the inconvenience.


GRB_name: GRB130427A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14579
SUBJECT: GRB 130427A: correction to GCN 14487
DATE:    13/05/05 21:50:56 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, on behalf of the Konus-Wind team, reports:

We have also found a typo in our GCN Circ. 14487 "Konus-Wind observation of GRB 130427A":
the correct energy range for the total K-W energy fluence and the peak flux estimations
for GRB 130427A is 20-10000 keV, not "20 - 1200 keV", as mentioned.

The 20-10000 keV range is a standard for K-W estimations of GRB energetics
in the observer frame.

We thank D.A.Kann for his help in clearing this issue and sorry again for the inconvenience.


GRB_name: GRB130505A
Detection_method: retraction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14580
SUBJECT: GRB 130505A: E_iso record retraction
DATE:    13/05/05 21:56:21 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann (TLS Tautenburg), and S. Schulze (PUC, MCSS) report:

Following the corrected Konus-Wind energy range (Frederiks, GCN 14578), we
recalculated E_iso for GRBs 130505A and 130427A (affected by the same
error in GCN 14487, Frederiks, GCN 14579), finding log E_iso,bol = 54.48
+/- 0.01 and 53.89 +/- 0.002, respectively.

This makes GRB 130505A comparable to GRB 080916C, and still one of the
most energetic GRBs ever discovered, but not the most energetic of all.


GRB_name: GRB130502A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14581
SUBJECT: GRB 130502A: optical upper limit
DATE:    13/05/05 22:25:32 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Rumyantsev (CrAO), K.Antoniuk (CrAO), A. Pozanenko (IKI) report on 
behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 130502A (Troja et al., GCN 14527) 
with AZT-11 telescope of CrAO observatory on May 02 starting on (UT) 
18:20:46, i.e. ~30 min after burst trigger. We took several images in 
R-filter of 180 s exposure.  Within enchanced XRT position (Beardmore et 
al., GCN  14536) we do  not detect any source. Preliminary photometry of 
a combined image is following

T_start (UT)           T0+     Filter  Exp. OT  UpperLimit (3 sigma)
                        mid,days        s

2013-05-02T18:20:46.18 0.0419  R      3600  n/d 20.8

The photometry is based on USNO-B1.0  star 0898-0181247
09 14 15.80 -00 08 13.7 assuming R=18.02.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14582
SUBJECT: GRB 130427A: optical observations in CrAO
DATE:    13/05/05 22:29:40 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Rumyantsev (CrAO), K.Antoniuk (CrAO),  D. Shakhovskoy (CrAO), A. 
Pozanenko (IKI) report on  behalf of larger GRB follow-up collaboration:

We continue observation of the Swift GRB 130427A (Maselli et  al., GCN 
14448)  with AZT-11 telescope of CrAO observatory. Preliminary 
photometry the optical afterglow of GRB 130427A (Maselli et al., GCN 
14448, Elenin et al. GCN 14450, Perley GCN 14451) is following

T_start (UT)             T0+     Filter Exp.  OT
                          mid,days       s     mag
2013-05-02T19:34:45.35   5.5618  R      6120  19.75 +/- 0.15
2013-05-03T20:41:27.17   6.5581  R      3600  20.30 +/- 0.25
2013-05-04T18:26:22.25   7.4747  R      5400  20.20 +/- 0.18

Photometry is based on SDSS star
SDSS id             B      eB    V      eV    R      eR    I      eI
J113220,11+274133,5 17,421 0,020 16,911 0,020 16,561 0,015 16,124 0,016


GRB_name: GRB130504C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14583
SUBJECT: GRB 130504C: Fermi GBM detection
DATE:    13/05/05 23:54:40 GMT
FROM:    Michael Burgess at UAH  <james.m.burgess@nasa.gov>

J. Michael Burgess (UAH), Valerie Connaughton (UAH) and Shaolin Xiong (UAH)
report on behalf of the Fermi GBM Team:

"At 23:28:57.518 UT on 04 May 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130504C (trigger 389402940 / 130504978).

High peak flux from the GRB caused GBM to issue a repoint request
that reoriented the satellite to place the GRB near the LAT boresight
for 2.5 hours, subject to Earth limb contraints.

The on-ground calculated location, using the GBM trigger
data, is RA = 90.71, DEC = 4.45 (J2000 degrees,
equivalent to 06 h 02 m, 4 d 27 '), with an uncertainty
of 1.0 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
This location is consistent with the LAT location.
The angle from the Fermi LAT boresight is 47 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of about 5 peaks associated with the GRB and 1 peak 
associated with a solar flare about 100 seconds prior to T0.
The duration (T90) of the GRB is about 74 s (50-300 keV).
The time-averaged spectrum from T0-2.0 s to T0+120.0 s is
adequately fit by a Band function with 
Epeak = 637 +/- 34 keV, alpha = -1.23 +/- 0.01, 
and beta = -2.28 +/- 0.08

The event fluence (10-1000 keV) in this time interval is
(1.34 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+30.8 s in the 10-1000 keV band
is 43 +/- 0.5 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130504C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14584
SUBJECT: GRB 130504C: Swift-XRT observations
DATE:    13/05/06 00:33:18 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, A. Melandri (INAF-OAB) report on behalf of  the Swift team:

We have analysed 1.3 ks of Swift-XRT data for the Fermi 130504C (Kocevski
GCN Circ. 14574; Burgess et al. GCN Circ. 14583), from 65.6 ks to 70.1 ks
after the LAT trigger. The data are all in Photon Counting (PC) mode.

We detect an uncatalogued X-ray source inside the LAT error circle
(Kocevski GCN Circ. 14574), at the following position: RA, Dec=91.63047,
3.83388 which is equivalent to:

RA (J2000): 06 06 31.3
Dec (J2000): +03 50 01.96

with an uncertainty of 4.8 arcsec (radius, 90% confidence).
The count rate at this position is (4.4 +/- 0.7) x 10^-2 cts/s. At the
present stage, it is not possible to determine whether the source is
fading.


GRB_name: GRB130505A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14585
SUBJECT: GRB 130505A: optical observations
DATE:    13/05/06 02:27:34 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

Yu. Krugly (IA KhNU), I. Slyusarev (IA KhNU),  I. Molotov (KIAM), A. 
Pozanenko (IKI) report on behalf of larger collaboration:

We observed a filed of the Swift GRB 130505A (Cannizzo  et al. GCN 14563) 
with  0.7m  telescope of Institute of Astronomy, Kharkiv National University 
between  May 05 (UT) 20:52:35 - 21:19:57. A set of images of 180 s were 
taken in R-filter. In the combined image we clearly  detect optical 
afterglow (Cannizzo  et al., GCN 14563; Tanvir et al., GCN 14567; Kuroda et 
al., GCN 14568). Preliminary photometry is based on the nearby SDSS stars:

T_start (UT)                 T0+                Filter   Exp.     OT
                                  mid,days                   s         mag

2013-05-05T20:52:35    0.5309            R        8x180   19.4 +/- 0.07


GRB_name: GRB130505B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14586
SUBJECT: GRB 130505B: MAXI/GSC detection
DATE:    13/05/06 09:23:09 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

M. Serino (RIKEN), H. Negoro (Nihon U.), 
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa (JAXA), 
T. Mihara, M. Sugizaki, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), 
N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Nakano, Y. Kawakubo (AGU), 
H. Tsunemi, M. Sasaki (Osaka U.), 
M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.), 
Y. Ueda, M. Shidatsu, T. Kawamuro (Kyoto U.), 
Y. Tsuboi, M. Higa (Chuo U.), 
M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.), 
K. Yamaoka (Nagoya U.) report on behalf of the MAXI team

At 2013-05-05T23:54 UT, the MAXI/GSC detected an uncatalogued X-ray
transient source. Assuming a constant source flux over the scan transit,
we obtain the source position at 

 (R.A., Dec.) = (139.500 deg 1.500 deg) = (09 18 00, +01 30 00)(J2000)

with a 90% C.L. statistical error of 0.3 deg and an additional systematic 
uncertainty of 0.1 deg (90% containment radius). 

The averaged X-ray flux was 160 +/- 40  mCrab (4-10 keV). 
There were no significant excess fluxes at the previous
and followed scan transits at 2013/05/05 22:20 UT and 2013/05/06 01:26 UT, respectively, 
with an upper limit of 20 mCrab for each.


GRB_name: GRB130504C
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14587
SUBJECT: Konus-Wind observation of GRB 130504C
DATE:    13/05/06 11:08:40 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration intense GRB 130504C
(Fermi-LAT detection: Kocevski et al., GCN 14574;
Fermi-GBM detection: Burgess et al., GCN 14583)
triggered Konus-Wind at T0=84544.491s UT (23:29:04.491)

The light curve shows multiple partly overlapped peaks
from ~T0-15 s to ~T0+105s.
The emission is seen up to 12 MeV.

A possible hard precursor is seen in the 360-1400 keV
light curve at ~T0-50s, but its attribution to GRB 130504C
is yet unclear.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130504_T84544/

As observed by Konus-Wind, the burst
had a fluence of (2.0  0.1)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+21.440s,
of (2.6  0.2)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+105.216 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.32  0.04,
the high energy photon index beta = -2.15  0.1,
the peak energy Ep = 452  49 keV,
chi2 = 110/97 dof.

The spectrum at the maximum count rate
(measured from T0+21.248 to T0+23.296 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.74  0.12,
the high energy photon index beta = -1.93  0.06,
the peak energy Ep = 251  38 keV,
chi2 = 61/66 dof.

All the quoted results are preliminary.


GRB_name: GRB130504C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14588
SUBJECT: GRB 130504C: further Swift-XRT observations
DATE:    13/05/06 14:14:28 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, A. Melandri (INAF-OAB), P.A. Evans (U. Leicester) report on
behalf of the Swift-XRT team:

We have analysed 7.7 ks of XRT data for the Fermi-LAT-detected burst: GRB
130504C,  from 65.6 ks to 93.3 ks after the  Fermi-LAT trigger. The data
are entirely in Photon Counting (PC) mode. The  X-ray source reported by
D'Avanzo et al. (GCN Circ. 14584) displays behaviour consistent with
fading. We propose it as the X-ray afterglow of GRB 130504C.

The refined XRT position is RA, Dec = 91.63038, +3.8339 which is
equivalent to:

RA (J2000): 06 06 31.29
Dec(J2000): +03 50 02.0

with an uncertainty of 3.6 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay index
of alpha=1.3 (+/-1.0).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.8 (+/-0.3). The best-fitting
absorption column is  5.1 (+2.0, -1.6) x 10^21 cm^-2, in excess of the
Galactic value of 2.5 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to
observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 5.0 x 10^-11 (7.9 x 10^-11) erg cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column:             5.1 (+2.0, -1.6) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^21 cm^-2
Excess significance: 2.7 sigma
Photon index:             1.8 (+/-0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020267.

This circular is an official product of the Swift-XRT team.

[GCN OPS NOTE(06may13): Per author's request, the extra "further" was removed
from the ubject-line.]


GRB_name: GRB130505A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14589
SUBJECT: GRB 130505A, Swift-BAT refined analysis
DATE:    13/05/06 17:01:01 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (NASA/GSFC/ORAU), J. R. Cummings (GSFC/UMBC), T. Sakamoto (AGU),
C. B. Markwardt (GSFC), S . D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. K. Cannizzo (NASA/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), D. M. Palmer (LANL),
M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130505A (trigger #555163)
(Cannizzo, et al., GCN Circ. 14563).  The BAT ground-calculated position is
RA, Dec = 137.060, 17.485 deg which is
   RA(J2000)  =  09h 08m 14s
   Dec(J2000) = +17d 29' 06"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 2%.

The mask-weighted light curve starts at ~T-3 sec, peaks at ~T+0.3 sec,
drops sginificantly at ~T+5 sec, and then has a long tail out to ~T+350 sec.
T90 (15-350 keV) is 88 +- 10 sec (estimated error including systematics).

The time-averaged spectrum from T-3.0 to T+363.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.18 +- 0.07.  The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-05 erg/cm2.
The 1-sec peak photon flux measured from T+1.44 sec in the 15-150 keV band
is 30.0 +- 3.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. The spectral results may be skewed toward harder values because of
the effects of the extreme partial coding.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555163/BA/


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14590
SUBJECT: GRB 130427A: RHESSI observations
DATE:    13/05/06 17:37:44 GMT
FROM:    Kevin Hurley at UCBerkeley/SSL  <khurley@ssl.berkeley.edu>

David M. Smith (UC Santa Cruz), Andre Csillaghy (Fachhochschule Nordwestschweiz),
Kevin Hurley (UC Berkeley), Hugh Hudson (UC Berkeley, U. Glasgow), Steven Boggs
(UC Berkeley), and Andrew Inglis (NASA Goddard/CUA) report:

The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)
satellite observed the prompt emission of GRB 130427A (Maselli et
al. , GCN 14448), with usable data over the approximate range 50 keV to
15 MeV, and a time resolution of 1us on each photon recorded.
Absolute timing accuracy is ~1ms.  Since the GRB was 122 degrees from
the Sun, the photons entered through the rear of the spectrometer.

The lightcurve of the main outburst in three energy bands is shown binned to 25ms 
resolution at:
http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_longplot.gif
The black, red, and orange lightcurves represent the energy ranges 50 keV to 1 MeV,
1-5 MeV, and 5-15 MeV, respectively.  

The lightcurve of the slower, fainter peak of the GRB, about two minutes after
the primary outburst, is shown here:
http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_lateplot.gif
The black, red, and orange lightcurves in this case represent the energy ranges 
50-200 keV, 200-500 keV, and 500 keV to 1 MeV, respectively.

RHESSI data are publicly available.  We invite anyone intending to use the RHESSI
data to consult with us about instrumental issues associated with the observation.


GRB_name: GRB130502B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14591
SUBJECT: Refined IPN Triangulation of GRB 130502B
DATE:    13/05/06 22:33:41 GMT
FROM:    Kevin Hurley at UCBerkeley/SSL  <khurley@ssl.berkeley.edu>

K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team, 

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, 
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team,

D. M. Smith, on behalf of the RHESSI GRB team, 

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of
the Swift-BAT team,

E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, I. Lapshov,
F. Lazzarotto, and M. Marisaldi, on behalf of the AGILE Team, and

V. Connaughton, M. S. Briggs, C. Meegan, and V. Pelassa, 
on behalf of the Fermi GBM team, report:

GRB 130502B (von Kienlin et al., GCN 14530, Kocevski et al., GCN 14532,
Golenetskii et al., GCN 14542, Hurley et al. 14546) was also observed by 
Odyssey.  Using Odyssey data reduces the size of the previous error box
by about a factor of two: 

              RA(2000)                    DEC(2000)

CENTER:  66.714= 4 h 26 m 51 s      71.066= 71 d 03 ' 58 "
CORNERS: 66.893= 4 h 27 m 34 s      71.032= 71 d 01 ' 55 "
         67.092= 4 h 28 m 21 s      70.975= 70 d 58 ' 29 "
         66.334= 4 h 25 m 20 s      71.156= 71 d 09 ' 22 "
         66.535= 4 h 26 m 08 s      71.100= 71 d 05 ' 59 "

The area of this box is about 8 square arcminutes, and it still contains the
Swift-XRT source (Melandri et al., GCN 14540).  A new map has been posted at
ssl.berkeley.edu/ipn3/130502

Some improvement in this error box is possible.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14592
SUBJECT: GRB 130427A: Tautenburg afterglow observations
DATE:    13/05/06 22:41:33 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann, B. Stecklum, and F. Ludwig (TLS Tautenburg) report:

We observed the optical afterglow (Elenin et al., GCN 14450) of the nearby
(Levan et al., GCN 14455), extremely bright GRB 130427A (Maselli et al.,
GCN 14448; Zhu et al., GCN 14471; von Kienlin, GCN 14473; Golenetskii et
al., GCN 14487) with the 1.34m Schmidt telescope of the Thueringer
Landessternwarte Tautenburg equipped with a 4k CCD camera under good
weather conditions. We obtained 3 x 600 sec frames in the Rc band. The
afterglow is detected in each frame.

Using the nearby star given in Rumyantsev et al. (GCN 14582), we derive a
preliminary magnitude of Rc = 20.27 +/- 0.07 at 8.55173 days after the
GRB.

This value is in good agreement with detections from the last few days
(Kuroda et al., GCN 14534; Rumyantsev et al., GCN 14582). The afterglow
does not yet show clear signs of flattening associated with either a
rising supernova component or a significant contribution from the
underlying host galaxy.

This message may be cited.


GRB_name: GRB130505A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14593
SUBJECT: GRB 130505A: Tautenburg afterglow observations
DATE:    13/05/06 22:41:36 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann, B. Stecklum, and F. Ludwig (TLS Tautenburg) report:

We observed the optical afterglow (Cannizzo et al., GCN 14563) of the
extremely luminous GRB 130505A (Cannizzo et al., GCN 14563; Golenetskii et
al., GCN 14575) with the 1.34m Schmidt telescope of the Thueringer
Landessternwarte Tautenburg equipped with a 4k CCD camera under good
weather conditions. We obtained 3 x 300 sec frames in the Rc band. The
afterglow is detected in each frame.

For a nearby SDSS star (RA = 137.082047, Dec. = 17.486120), using the
transformations of Lupton (2005), we find: B = 18.118, V = 17.080, Rc =
16.501, Ic = 15.967.

Using this star for calibration, we derive a preliminary magnitude of Rc =
19.09 +/- 0.06 at 0.49118 days after the GRB.

This message may be cited.


GRB_name: GRB130505B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14594
SUBJECT: GRB 130505B: Swift Candidate Afterglow
DATE:    13/05/06 23:15:51 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

D. Kocevski (NASA/GSFC/ORAU), F. E. Marshall (NASA/GSFC), 
M. De Pasquale (MSSL-UCL), P. D'Avanzo (INAF-OAB), 
and A. Melandri (INAF-OAB) report on behalf of the Swift team:

The Swift began tiling observations of the field of GRB 130505B
16 hours after the MAXI trigger (Serino et al., GCN Circ. 14586).
A bright source not in the DSS is seen in the UVOT observation
at a preliminary position of 
   RA(J2000)  =    09:17:22.18 = 139.34124
   DEC(J2000) =   +01:42:03.1  =  +1.70085
with a 90%-confidence error radius of about 0.6 arc sec.
It is not possible to determine whether the source is varying
with the currently available data.

The position is consistent with that of SDSS J091721.89+014203.2,
but more than 5 magnitudes brighter in the u band.
The SDSS source could be the host galaxy for the burst,
or could indicate that the MAXI source is a galactic transient.

The preliminary detection using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposure is:

Filter         T_start(s)   T_stop(s)      Exp(s)        Mag
u                58617        59042         425        18.0 +/- 0.1

The magnitude is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.024 in the direction of the burst
(Schlegel et al. 1998).

We have also analysed 426 s of Swift-XRT data from 58.6 ks 
to 59.0 ks after the MAXI trigger. The data are all in 
Photon Counting (PC) mode. A preliminary
analysis reveals the presence of a source at the following position 
RA, Dec = 139.34180, +1.70215 which is equivalent to:

RA (J2000): 09 17 22.03
Dec(J2000): +01 42 07.7

with an uncertainty of 4.5 arcsec (radius, 90% confidence). 
This position is consistent with the UVOT one. The observed count rate 
is (3.0 +/- 1.0) x 10^-2 cts/s.  Given the low significance of 
the detection, at the present stage, it is not possible to determine 
whether the source is variable.

Automated analysis of the XRT data can be found online at
http://www.swift.ac.uk/xrt_products/TILED_GRB00015/

Details of the XRT automated analysis methods are detailed in 
Evans et al. (2007, A&A, 469, 379; and 2009, MNRAS, 397, 1177).

Additional observations with Swift are scheduled. Observations
with other observatories of this interesting object are encouraged.


GRB_name: GRB130505A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14595
SUBJECT: GRB 130505A: RATIR Optical and NIR Observations
DATE:    13/05/07 18:14:30 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We observed the field of GRB 130505A (Cannizzo, et al., GCN Circular
14563) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronmico Nacional on Sierra San Pedro Mrtir from 2013/05 7.13 to
2013/05 7.22 UTC (42.84 to 44.87 hours after the BAT trigger), obtaining
a total of 0.36 hours exposure in the r' and i' bands and 0.14 hours
exposure in the Z, Y, J, and H bands.

The optical counterpart (Evans et al., GCN Circular 14569) is clearly
identified. We obtain the following detections and 3-sigma upper limits:

 r' = 21.10  0.27
 i' = 20.98  0.23
 Z > 21.17
 Y > 19.15
 J > 18.38
 H > 17.15

These magnitudes are in the AB system, are calibrated by comparison with
SDSS DR8 and 2MASS, and not corrected for Galactic extinction in the
direction of the GRB. The quoted uncertainties on the detections are 1
sigma.

We thus confirm the fading reported by other observers at earlier epochs
(Kuroda et al., GCN Circular 14568; Xu et al, GCN Circular 14570; Xin et
al., GCN Circular 14571; Hentunen et al, GCN Circular 14572; Krugly et
al., GCN Circular 14585; and Kann et al., GCN Circular 14593).

No further observations of this source are planned.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14596
SUBJECT: GRB 130427A: Amateur observations from Sweden
DATE:    13/05/07 19:05:46 GMT
FROM:    Lars Hermansson at Uppsala Amateur Astronomers  <lars.hermansson4@comhem.se>

L. Hermansson, P. Holmstrm, M. Johansson (Sandvreten Observatory, Sweden)

We observed the field of GRB 130427A (Maselli et al., GCN 14448; Elenin et
al., GCN 14450) with the 0.45 m f/4.5 Newton located at Sandvreten
Observatory, Sweden.

Observations were obtained between 2013-Apr-27 22:29:03 and 23:48:43 UT. Two
images each were obtained in each of B, V, Rc and Ic bands with Schler
Johnson-Cousins photometric filters and an SBIG ST-7E CCD.

The following magnitudes were obtained from the observations with Maxim DL
software using four SDSS comparison stars transformed to the BVRI system
using Lupton (2005). Magnitudes are not corrected for extinction.

Filter    Tmid (T0+day)   Exp (s)    Mag         Err
B         0.65231         2x600      17.74       0.06
V         0.63317         2x300      17.38       0.03
Rc        0.61726         2x300      16.99       0.03
Ic        0.66821         2x300      16.78       0.05

We wish to thank D. A. Kann and the Cosmoquest forum for alerting us to GRB
130427A. We are also grateful for the guidance D.A. Kann provided during the
preparation of this report.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14597
SUBJECT: GRB 130427A: Excess optical emission consistent with an emerging supernova
DATE:    13/05/07 21:28:28 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T.
Kruehler, D. Malesani (DARK/NBI), G. Leloudas (OKC, Stockholm and
DARK/NBI), J.P.U. Fynbo, J. Hjorth, (DARK/NBI), S. Schulze (PUC and
MCSS), P. Jakobsson, Z. Cano (U. Iceland), J. Gorosabel
(IAA-CSIC/UPV-EHU), report:

We have been monitoring the optical counterpart of GRB 130427A
(Maselli et al., GCN 14448; Elenin et al., 14450) starting 12.85 hr
after the GRB trigger (Xu et al., GCN 14478), mainly using the 2.5
Nordic  Optical Telescope (NOT) equipped with the ALFOSC camera.
Observations were carried out using the SDSS filters.

The light curve between ~1.0 and 5.0 days after the trigger (observer
frame) is well fit by a power law with decay index 1.3. Starting from
day 5.0, however, the light curve gradually flattens. The flattening,
albeit reduced, is still evident after subtracting the (known) flux
contribution of the host galaxy. In particular, clear flux in excess
of the afterglow and host contribution is apparent on May 5 and 6,
that is 8.6 and 9.6 days after the GRB.

Photometry in the Sloan griz filters was secured during the night of
May 6. After subtracting from the observed flux the host contribution,
and correcting for the (small) Galactic extinction, the SED clearly
deviates from a power-law, in sharp contrast with our earlier
measurements and the typical spectrum of GRB afterglows. Instead, the
griz SED shows a broad hump peaking in the i and r bands, which is
roughly consistent with the spectrum of other broad-lined SNe
associated with GRBs at comparable epochs (e.g., SN 1998bw: Patat et
al. ApJ, 555 900; SN 2006aj: Pian et al., Nat. 442,1011).

The flattening in the decay, the change of the spectral shape, and the
overall flux level are all consistent with the emergence of a SN,
though detailed spectroscopy and long-term monitoring will be required
to fully assess the nature of the flux excess.


GRB_name: GRB130427A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14598
SUBJECT: GRB 130427A, Watcher afterglow detection
DATE:    13/05/07 22:00:53 GMT
FROM:    Martin Topinka at UCD, Dublin  <martin.topinka@gmail.com>

Martin Topinka, Lorraine Hanlon, Pete Tisdall, Seamus Meehan, Antonio Martin-Carrillo (UCD, Dublin) and Petr KubÃ¡nek (FZÃš AVÄŒR, Praha) on behalf of the Watcher telescope team, report:

We followed the Swift detection of GRB 130427A (Maselli et al., GCN 14448, Swift trigger 554620) with the Watcher robotic telescope (D=40cm) located at Boyden Observatory, near Bloemfontein in South Africa.

We started imaging the field at 16:43:55 UT on 2013-04-27 (i.e. 8.9 hr after the BAT trigger) taking 2 minute exposures in the clear filter using an Andor CCD camera.

The optical afterglow (Elenin et al., GCN 14450) is clearly detected. Preliminary analysis of some of the initial images gives a magnitude for the optical afterglow of 16.59+/-0.04 @ 17:00:35 UT and 16.79+/-0.07 @ 18:59:13 UT.

Magnitudes were estimated using several nearby USNO-B1 stars as references and are not corrected for galactic dust extinction. Further analysis of these images is on-going. The field continues to be regularly observed with Watcher.

This message is quotable in publications.


GRB_name: GRB130505A
Detection_method: Suzaku WAM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14599
SUBJECT: GRB 130505A: Suzaku WAM observation of the prompt emission
DATE:    13/05/08 04:30:49 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro@phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno, S. Sugimoto
(Saitama U.), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui,
Y. Fukazawa (Hiroshima U.), M. Yamauchi, N. Ohmori, M. Akiyama
(Univ. of Miyazaki), K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.),
Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri
(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:


The bright, long GRB 13505A (GCN 14563; Cannizzo et al.)
triggered the Suzaku Wide-band  All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at  UT 08:22:24.527 (=T0).

The observed light curve shows a bright peak followed by a weaker
emission seen up to T0+30 s with a duration (T90) of about 14 seconds.
The fluence in 100 - 1000 keV was 1.06 (+0.05/-0.05) x10^-4 erg/cm^2.
The 1-s peak flux measured from T0+4 s was
53.1 (+2.0/-2.5) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-2 s to T0+30 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -0.99 (+0.17/-0.11),
the high-energy photon index beta: -2.33 (+0.06/-0.07),
and the peak energy Epeak: 1094 (+131/-175) keV (chi^2/d.o.f = 23.9/23).
Using a redshift of z = 2.27 (Tanvir et al., GCN 14567), we estimate
the isotropic energy release in the 1 keV - 10 MeV range to be
2.55 (+0.12/- 0.11) x10^54 erg and the peak energy at the rest frame
to be 3615 (+532/-469) keV, where cosmological parameters of the Omega
matter, the Omega lambda and the Hubble constant are fixed at 0.27, 0.73
and 70 km/s/Mpc respectively.

Due to the brightness of this burst, a 3% systematic error was added for
low energy channels.
All the quoted errors are at statistical 90% confidence level.

The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html


GRB_name: GRB130504B
Detection_method: Suzaku WAM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14600
SUBJECT: GRB 130504B: Suzaku WAM observation of the prompt emission
DATE:    13/05/08 04:30:55 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro@phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno, S. Sugimoto
(Saitama U.), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui,
Y. Fukazawa (Hiroshima U.), M. Yamauchi, N. Ohmori, M. Akiyama
(Univ. of Miyazaki), K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.),
Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri 
(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:


The bright, short, IPN localized GRB 130504B (GCN 14560;  von Kienlin et
al., GCN 14561; Golenetskii et al.) triggered the Suzaku Wide-band
All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV
at 07:32:03.063 UT (=T0).

The observed light curve shows a double-peaked structure starting at
T0+0.25 s, ending at T0+0.75 s with a duration (T90) of about
0.38 seconds.
The fluence in 100 - 1000 keV was 4.97(+0.15/-0.30) x10^-6 erg/cm^2.
The 1-s peak flux measured was 7.60 (+0.28/-0.54) photons/cm^2/s
in the same  energy range.

Preliminary result shows that the time-averaged spectrum from T0 to T0+1
s is well fitted by a power-law with exponential cutoff model:
dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha       0.41 (+0.20/-0.22), and
Epeak      1321 (+139/-129) keV (chi^2/d.o.f. = 35.1/24).

All the quoted errors are at statistical 90% confidence level.

The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html


GRB_name: GRB130504C
Detection_method: Suzaku WAM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14601
SUBJECT: GRB 130504C: Suzaku WAM observation of the prompt emission
DATE:    13/05/08 04:31:01 GMT
FROM:    Makoto Tashiro at Saitama U/Swift  <tashiro@phy.saitama-u.ac.jp>

T. Yasuda, M. Tashiro, Y. Terada, Y. Ishida, H. Ueno, S. Sugimoto
(Saitama U.), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui,
Y. Fukazawa (Hiroshima U.), M. Yamauchi, N. Ohmori, M. Akiyama
(Univ. of Miyazaki), K. Yamaoka (Nagoya U.),  S. Sugita (Ehime U.),
Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri
(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:


The bright, long GRB 130504C (GCN 14574; Fermi-LAT detection : Kocevski
et al.) triggered the Suzaku Wide-band  All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 23:29:00.540 UT (=T0).

The observed light curve shows a multi-peaked structure starting at T0-9
s, ending at T0+110 s with a duration (T90) of about 67 seconds.
The fluence in 100 - 1000 keV was 9.11 (+0.14/-0.51) x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+ 27 s was
15.9 (+0.3/-4.0) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-9 s to T0+110 s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha:  -1.59 (+0.17/-0.12),
the high-energy photon index beta: -2.43 (+0.17/-0.33),
and the peak energy Epeak: 845 (+227/-159) keV (chi^2/d.o.f = 77.0/50).

Due to the brightness of this burst, a 1% systematic error was added for
low energy channels.
All the quoted errors are at statistical 90% confidence level.

The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html


GRB_name: GRB130505A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14602
SUBJECT: GRB 130505A: MITSuME Akeno Optical observation
DATE:    13/05/08 11:41:21 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

T. Yoshii, Y. Yatsu, Y. Yano,  R. Usui, Y. Tachibana, K. Ito,
S. Kurita, Y. Saito, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed GRB 130505A (Maselli et al., GCNC 14563) with an
optical tri-color (g, Rc, and Ic)  camera attached to the MITSuME
50 cm telescope of Akeno Observatory, Yamanashi, Japan.

The observation started at 2013-05-05 11:04:17 UT (9709 sec after the
trigger).
And we detected the previously reported afterglow .
The measured magnitudes were listed below.

T0+[MID]   MID-UT   T-EXP[sec]    g'                 Rc                Ic
-----------------------------------------------------------------------------------------------------
 15550s     12:41:38     3480    18.8+/-0.1     18.9+/-0.2      18.0+/-0.1
-----------------------------------------------------------------------------------------------------
T-EXP: Total Exposure time [sec]
(The photon flux were calibrated against GSC2.3 catalog.)


GRB_name: GRB130504C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14603
SUBJECT: GRB 130504C: Swift-XRT afterglow confirmation
DATE:    13/05/08 15:13:43 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo (INAF-OAB), A.Y. Lien (NASA-GSFC), P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team:

We have analysed 12.3 ks of XRT data for the Fermi-LAT-detected burst GRB
130504C (Kocevski et al. GCn Circ 14574),  from 65.6 ks to 278.7 ks after
the  Fermi-LAT trigger. The data are entirely in Photon Counting (PC)
mode.  The X-ray source reported by D'Avanzo et al. (GCN Circ. 14584,
14588) displays a fading behaviour.

The overall light curve can be modelled with a power-law decay with a
decay index of alpha=1.39 (+0.32, -0.25).

We confirm it as the X-ray afterglow of GRB 130504C.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020267.


GRB_name: GRB130505B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14604
SUBJECT: GRB 130505B: Further Swift observations
DATE:    13/05/08 15:39:28 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri, P. D'Avanzo, (INAF-OAB), M. De Pasquale, S. Oates (MSSL/ 
UCL), D. Kocevski (NASA/GSFC/ORAU), F. E. Marshall (NASA/GSFC), P. A.  
Evans (U. Leicester) on behalf of the Swift team

The optical source identified by Swift/UVOT in the field of MAXI  
GRB130505B (Kocevski et al., GCN circ. 14594) and coincident with SDSS  
J091721.89+014203.2 has dimmed by more than 3 magnitudes between 58.6  
and 86.7 ks after the trigger (Serino et al., GCN circ. 14586), and it  
is not detected in the last exposure, centered at 153.9 ks, down to a  
3 sigma upper limit of u=22.1.

This source is seen to be fading also by Swift/XRT between 58.6 and  
163.0 ks with a decay index ~2.6. The spectrum can be fitted with an  
absorbed power-law with a spectral photon index of 2.19 (+2.09,  
-0.79). The best fitting absorption column is 1.6 (+4.1, -1.6)  10^21  
cm-2, consistent with the Galactic value of 2.4 x 10^20 cm-2 (Kalberla  
et al. 2005). Assuming this spectrum, the last XRT detection  
correspond to a 0.3-10 keV flux of (4.5  2.2) x 10^-14 erg cm-2 s-1.

The very fast optical decay is unprecedented in GRB afterglows, and we  
cannot exclude a Galactic transient nature for this transient.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14605
SUBJECT: GRB 130427A, LBT optical spectrum
DATE:    13/05/08 15:46:33 GMT
FROM:    Peter Garnavich at U of Notre Dame  <pgarnavi@nd.edu>

P. Garnavich (Notre Dame) reports:

A spectrum of the GRB 130427A afterglow was obtained with the
Large Binocular Telescope (LBT+MODS1 instrument) on 2013 May 7.15 (UT),
9.8 days after the burst. The spectrum covers 340 nm to 950 nm and
is dominated by a power-law continuum. Narrow Balmer, [OII], [OIII]
emission lines, and MgII and MgI absorption lines from the host
galaxy are present at a redshift of 0.340.

The LBT spectrum shows no obvious undulations characteristic of a
broad-lined type Ic supernova such as SN 1998bw. In contrast,
a 98bw-like supernova was detectable from GRB 030329 around
seven days after its burst (Stanek et al. 2003, ApJ, 591, L17).
This early detection was primarily due to the prominent peak
seen around 500 nm (rest frame) in broad-lined type Ic events.

Adding a pre-maximum spectrum of SN 1998bw
(Patat et al. 2001, ApJ, 555, 900) to a power-law continuum
suggests that any 98bw-like supernova is at least an R-band
magnitude fainter than the afterglow 10 days after the
GRB 130427A burst.

I thank Rick Pogge, Paul Martini and Scott Adams for help in
obtaining the spectra.
The LBT is an international collaboration among institutions in the
United States, Italy and Germany. LBT Corporation partners are:
The University of Arizona on behalf of the Arizona university system;
Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft,
Germany, representing the Max-Planck Society, the Astrophysical
Institute Potsdam, and Heidelberg University; The Ohio State University,
and The Research Corporation, on behalf of The University of Notre Dame,
University of Minnesota and University of Virginia.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14606
SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations
DATE:    13/05/08 16:34:04 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We have been monitoring GRB 130427A with the Reionization and
Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold
Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San
Pedro Mrtir. We have precise and homogeneous photometry for all nights
except 2013 May 6.

During the first night the optical afterglow is well-fitted by a power
law with an index of -1. However, around 1 day after the burst there is
a break, and the power law steepens.

Our photometry in gri from 2 to 11 days is well-fitted by a power law
with an index very close to -1.5 plus a constant contribution with i =
21.23  0.05, g-i =  0.74  0.12, and r-i =  0.05  0.05, consistent
with the SDSS DR9 photometry of the presumed host galaxy.

We see no evidence for an additional component such as the one mentioned
by Xu et al. (GCN Circular 14597).

Further observations are planned.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130508A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14607
SUBJECT: GRB 130508A: Swift detection of a probable burst
DATE:    13/05/08 17:44:12 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

S. T. Holland (STScI), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), D. Malesani (DARK/NBI),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU),
E. Troja (NASA/GSFC/UMCP) and B.-B. Zhang (PSU) report on behalf of
the Swift Team:

At 17:08:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a probable GRB 130508A (trigger=555413).  Swift slewed immediately to the 
source location. 
The BAT on-board calculated location is 
RA, Dec 305.312, +34.949 which is 
   RA(J2000)  =  20h 21m 15s
   Dec(J2000) = +34d 56' 58"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The real-time lightcurve shows a weak peak
with a duration of about 40 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~18 sec after the trigger. 

The XRT began observing the field at 17:11:03.9 UT, 130.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued
X-ray source with an enhanced position: RA, Dec 305.3217, 34.9583 which
is equivalent to:
   RA(J2000)  = 20h 21m 17.20s
   Dec(J2000) = +34d 57' 29.9"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 44 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

The on-board calculated light curve shows evidence for a strong flare in 
Windowed Timing mode data at about 145-150 s after the BAT trigger. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (7.72 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 1
(+1.60/-1.01) x 10^22 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 135 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the large, but uncertain extinction expected. 

Even though this is a weak detection and it is on the Galactic Plane
(lon,lat= 74,-1), we determine that this is probably a GRB, but can not rule out
some other type of astrophysical source.  We will need the full data set 
to make the determination. 

Burst Advocate for this burst is S. T. Holland (sholland AT stsci.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130427A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14608
SUBJECT: GRB 130427A: Ten nights of Skynet/PROMPT/GORT observations
DATE:    13/05/08 19:14:43 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, K. McLin, L. Cominsky, 
T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, 
M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:

Skynet continued observing the Swift/XRT localization of GRB 130427A 
(Maselli et al., GCN 14448, Swift trigger #554620) with four 16" 
telescopes of the PROMPT array at CTIO, Chile (BVRI bands), and with the 
14" GLAST Optical Robotic Telescope (GORT) at the Hume Observatory in 
California (RcIc bands). Our observations span 10 nights, from t=0.65 to 
10.8 days post-trigger. Skynet has taken 2684 160-second exposures on 
the 4 PROMPT telescopes, and 360 160-second exposures on GORT, or a 
total of over 135 hours on source. We performed photometry on each 
exposure, calibrated to two SDSS stars in the field. We stacked 
exposures to improve sensitivity, in groups ranging from 3 exposures on 
night 1, to 60 exposures on night 10.

We detect a fading afterglow in BVRI at the position reported by Elenin 
et al. (GCN 14450), which is ~50" south of the initial XRT localization. 
From night 2 onwards, the light curves fade with an approximate power 
law index alpha=-1 (with no corrections for the known host galaxy flux). 
We see some evidence for flattening of the I-band light curve beginning 
at t~8 days, and of the R-band curve at t~10 days, though it is not 
clear whether this is due to host galaxy contamination or to an 
intrinsic re-brightening.

A preliminary light curve including all Skynet observations through 
t=10.8 days is at:
http://skynet.unc.edu/grb/grb130427a_10.png

See Trotter et al. (GCN 14497, GCN 14510) for descriptions and light 
curves of the first and second nights' observations. Further Skynet 
observations are ongoing.


GRB_name: GRB130508A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14609
SUBJECT: GRB130508A: BOOTES-3 optical limit
DATE:    13/05/08 19:34:53 GMT
FROM:    Juan Carlos Tello at IAA-CSIC  <jtello@iaa.es>

J.C. Tello, R. Snchez-Ramirez, M. Jelinek (IAA-CSIC Granada), J. Gorosabel
(UPV/EHU-IAA/CSIC), W. Allen (Vintage Lane Obs.), Ph. Yock (Auckland
Univ.), P. Kubanek (IP AS CR & IAA-CSIC), and A. J. Castro-Tirado
(IAA-CSIC) report on behalf of a larger collaboration:

"We observed the field of GRB 130508A (Holland et al., GCNC 14607),
detected by Swift/BAT, with the 0.6m Yock-Allen robotic telescope
(BOOTES-3) located in Blenheim, New Zealand. Unfiltered images were
obtained starting 17:10:28UT (94 seconds after the burst, 17.65s after
receiving the first GCN packet). The combined exposure of 120 images of 0.5
seconds each revealed no uncatalogued sources within the XRT uncertainty
circle down to a magnitude of R Mag~15 when compared to the USNO-B1
catalogue. Further images of longer exposure revealed no other sources and
did not provide a significantly better limit."


GRB_name: GRB130508A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14611
SUBJECT: GRB 130508A: MITSuME Okayama upper limits
DATE:    13/05/09 00:17:17 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130508A (Holland et al., GCNC 14607)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-05-08 17:10:40 UT (~1.8 min after the burst).
We did not find any new point source within the XRT error circle
(Holland et al., GCNC 14607) in all the three bands.

Photometric results of the OT are listed below.
We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.04312    18:10:59    6360.0   >20.5  >20.4  >19.1
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130508A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14612
SUBJECT: GRB 130508A: Swift-XRT refined Analysis
DATE:    13/05/09 10:34:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz
(U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli 
(INAF-IASFPA), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU)
and S.T. Holland report on behalf of the Swift-XRT team:

We have analysed xx ks of XRT data for GRB 130508A (Holland  et al. GCN
Circ. 14607),  from 0 s to 0 s after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The best available XRT position 
(using the promptly downlinked event data, the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec =
305.3218, 34.9583 which is equivalent to:

RA (J2000): 20 21 17.22
Dec(J2000): +34 57 29.9

with an uncertainty of 2.5 arcsec (radius, 90% confidence). We cannot
determine at the present time whether the source is fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.0 (+0.6, -0.5). The
best-fitting absorption column is  1.6 (+1.0, -0.8) x 10^22 cm^-2, in
excess of the Galactic value of 7.7 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 1.0 x 10^-10 (1.3 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+1.0, -0.8) x 10^22 cm^-2
Galactic foreground: 7.7 x 10^21 cm^-2
Excess significance: 1.7 sigma
Photon index:      1.0 (+0.6, -0.5)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555413.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130508A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14613
SUBJECT: GRB 130508A, Swift-BAT refined analysis
DATE:    13/05/09 10:46:07 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
S. T. Holland (STScI), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
  
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130508A (trigger #555413) (Holland, et al.,
GCN Circ. 14607).
The BAT ground-calculated position is RA, Dec = 305.351, 34.966 deg which is
    RA(J2000)  =  20h 21m 24.2s
    Dec(J2000) = +34d 57' 57.6"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).  The
partial coding was 60%.
  
The mask-weighted light curve shows a single peak from about T+9 to T+55 sec.
T90 (15-350 keV) is 42 +- 11 sec (estimated error including systematics).
  
The time-averaged spectrum from T+9.62 to T+56.75 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.23.  The fluence in the 15-150 keV band is 6.6 +- 1.0 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+11.07 sec in the 15-150 keV band
is 0.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555413/BA/


GRB_name: GRB130508A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14614
SUBJECT: GRB 130508A: Refined Swift-XRT analysis: Correction to GCN 14612
DATE:    13/05/09 11:03:24 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

GCN 14126 was sent in error, with several pieces of information missing, 
as new data were being processed as the circular was sent.

The corrected refined XRT analysis is as follows:


We have analysed 10 ks of XRT data for GRB 130508A (Holland  et al. GCN 
Circ. 14607),  from 134 s to 45.8 ks after the  BAT trigger. The data 
comprise 53 s in Windowed Timing (WT) mode with the remainder in Photon 
Counting (PC) mode. The best available XRT position  (using the promptly 
downlinked event data, the XRT-UVOT alignment and matching UVOT field 
sources to the USNO-B1 catalogue) is RA, Dec = 305.3218, 34.9583 which 
is equivalent to:

RA (J2000): 20 21 17.22
Dec(J2000): +34 57 29.9

with an uncertainty of 2.5 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay 
index of alpha=1.98 (+0.39, -0.28).

A spectrum formed from the PC mode data can be fitted with an absorbed 
power-law with a photon spectral index of 1.0 (+0.6, -0.5). The 
best-fitting absorption column is  1.6 (+1.0, -0.8) x 10^22 cm^-2, in 
excess of the Galactic value of 7.7 x 10^21 cm^-2 (Kalberla et al. 
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion 
factor deduced from this spectrum  is 1.0 x 10^-10 (1.3 x 10^-10) erg 
cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column:        1.6 (+1.0, -0.8) x 10^22 cm^-2
Galactic foreground: 7.7 x 10^21 cm^-2
Excess significance: 1.7 sigma
Photon index:        1.0 (+0.6, -0.5)

If the light curve continues to decay with a power-law decay index of 
1.98, the count rate at T+24 hours will be 6.0 x 10^-6 count s^-1, 
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.1 x 
10^-16 (7.8 x 10^-16) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at 
http://www.swift.ac.uk/xrt_products/00555413.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14615
SUBJECT: GRB 130427A: Keck/LRIS Observations
DATE:    13/05/09 15:39:04 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley and S. Tang (Caltech) report:

On the night of 2013-05-09 UT we observed the location of GRB 130427A 
with the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m 
telescope, during excellent weather conditions (clear skies and 0.7 
arcsecond seeing).

In a pair of 90 second g-band images we clearly detect the transient 
superimposed on a faint, extended source that we identify as the host 
galaxy.  While blended with the light of the transient, the diameter of 
this extended emission is approximately 3 arcseconds, corresponding to a 
physical size of ~14 kpc at a redshift of z=0.34.  The magnitude of the 
transient at this time (within a 1" aperture centered on the optical 
position) is:

  g = 21.23 +/- 0.04 mag  (t = 12.00 days)

This is consistent (within uncertainties) with the rate of decay seen in 
recent P60 observations between 1-8 days post-GRB after subtraction of 
the host galaxy.

We also acquired a deep sequence of spectroscopic observations (2000 sec 
total integration) with LRIS, covering a wavelength range from 
approximately 3250 to 10300 Angstroms.   We observe no broad features or 
other evidence of contribution of a supernova to the spectrum at this 
time, similar to as reported from LBT observations two nights previously 
(Garnavich et al., GCN 14605.)

We thank and S. R. Kulkarni and the PTF collaboration for these 
observations.


GRB_name: GRB130508A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14616
SUBJECT: GRB 130508A: RATIR Optical and NIR Observations
DATE:    13/05/09 16:42:06 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM),
Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130508A (Holland, et al., GCN 14607) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on
Sierra San Pedro Mrtir from 2013/05 9.36 to 2013/05 9.45 UTC (15.45 to
17.54 hours after the BAT trigger), obtaining a total of 1.42 hours
exposure in the r' and i' bands and 0.60 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Evans et al., GCN 14614),
in comparison with USNO-B1 and 2MASS, we obtain the following upper limits
(3-sigma):

  r' > 23.81
  i' > 23.53
  Z  > 21.95
  Y  > 21.66
  J  > 21.00
  H  > 20.42

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14617
SUBJECT: GRB 130427A: host galaxy observations
DATE:    13/05/09 20:03:02 GMT
FROM:    Klaas Wiersema at U Leicester  <kw113@leicester.ac.uk>

K. Wiersema (U. of Leicester), O. Vaduvescu (ING), N. Tanvir (U. of Leicester), 
A. Levan (Warwick) and O. Hartoog (U. of Amsterdam) report:

We observed the position of GRB 130427A with the 4.2m William Herschel telescope,
using the PFIP camera, on May 8th, under good seeing conditions (0.7 arcseconds). 
Exposures of 4x600 seconds were obtained using a narrowband filter covering 
the [O II] emission line doublet (3728 A) at the redshift of the 
GRB (z=0.3399; Levan et al., Xu et al. and Flores et al.; GCN 14455, 14478, 14491).
We used this filter to obtain the best visibility of the host galaxy against the bright afterglow
and possible supernova contribution.
The resulting data show a clear detection of the host galaxy. The GRB is located near, but
somewhat offset from, a brighter patch in the host. The host is an irregular galaxy, with
a broadly elliptical shape. The GRB is located North-West of the
majority of extended, smooth, host emission - a convenient choice in spectrograph slit
position angle may minimize host contamination and aid in identification of SN signatures.
The long axis of the host is approximately oriented along 70 degrees position angle (where
North=0, East = 90 degrees), and is approximately 3.4 arcseconds in length.

A jpg finder chart of the [OII] imaging can be found here:
http://www.star.le.ac.uk/~kw113/grb130427A/hostgalaxy_130427a.jpg

[GCN OPS NOTE(09may13): Per author's request, the "Apr 8" was changed to "May 8"
in the first sentence.]


GRB_name: GRB130508A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14618
SUBJECT: GRB 130508A: MITSuME Akeno upper limits
DATE:    13/05/10 13:04:03 GMT
FROM:    Yoichi Yatsu at Tokyo Tech.  <yatsu@hp.phys.titech.ac.jp>

Y. Saito, Y. Yano, R. Usui, Y. Tachibana, K. Ito, T. Yoshii,
S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130508A (Holland et al., GCNC 14607) with the
optical
three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope of Akeno Observatory, Yamanashi, Japan.

The observation started on 2013-05-08 17:10:32 UT ( ~99 sec after
the burst). And we could not find any new point source within the XRT
error circle (Holland et al., GCNC 14607) in all the three bands.

The results of photometry (3 sigma upper limits) are listed below.
We used GSC2.3 catalog for flux calibration.


T0+[sec]   MID-UT   T-EXP[sec]    g'           Rc          Ic
------------------------------------------------------------
-------------------------------
    283      17:13:30      240      >19.4   >19.1   >18.0
   2803      17:55:30     4320      >20.7   >20.4   >19.1
------------------------------------------------------------
-------------------------------
T0+ : Elapsed time after the burst [sec]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130508A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14619
SUBJECT: GRB 130508A: Swift/UVOT Upper Limits 
DATE:    13/05/10 20:39:01 GMT
FROM:    Stephen Holland at STScI  <sholland@stsci.edu>

S. T. Holland (STScI) reports on behalf of the Swift/UVOT team:

     The Swift/UVOT began settled observations of the field of GRB
130508A starting 136 s after the BAT trigger (Holland et al. 2013,
GCNC 14607).  We do not detect any new source consistent with the
UVOT-enhanced XRT position (Evans 2013, GCNC 14614) in any of the UVOT
exposures.  Preliminary 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the finding chart (FC) exposures and initial summed exposures are
presented below.

Filter       TSTART     TSTOP   Exposure      Mag
-------------------------------------------------
white (FC)      136       285        147    >20.8
u (FC)          296       545        246    >19.8
-------------------------------------------------
v              4416      5642        393    >20.0
b               551      6336        288    >20.5
u               296      6257        639    >20.5
uvw1           4417      6052        393    >20.3
uvm2           4212      5847        393    >20.3
uvw2           3801      5437        393    >20.5
white           136      5231        344    >21.5
-------------------------------------------------

     The quoted upper limits have not been corrected for the expected
extinction due to the Galactic reddening along the line of sight to
this burst of E(B-V) = 2.54 mag (Schlafly et al. 2011, ApJS, 737,
103).


GRB_name: GRB130511A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14620
SUBJECT: GRB 130511A: Swift detection of a burst with an optical counterpart
DATE:    13/05/11 11:42:24 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

H. A. Krimm (CRESST/GSFC/USRA), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 11:30:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130511A (trigger=555600).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 196.639, +18.698 which is 
   RA(J2000) = 13h 06m 33s
   Dec(J2000) = +18d 41' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single short
peak of duration ~0.5 sec followed by a 10-second tail. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 11:31:58.9 UT, 71.6 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 196.64698, 18.70893 which is equivalent
to:
   RA(J2000)  = 13h 06m 35.28s
   Dec(J2000) = +18d 42' 32.1"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 47 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.08 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5
(+1.47/-1.33) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 74 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 13:06:34.96 = 196.64567
  DEC(J2000) = +18:42:36.0  =  18.70999
with a 90%-confidence error radius of about 0.64 arc sec. This position is 7.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.18 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130511A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14621
SUBJECT: GRB 130511A: Gemini-North Redshift
DATE:    13/05/11 13:17:16 GMT
FROM:    Antonino Cucchiara at UCSC/UCO Lick  <acucchia@ucolick.org>

A. Cucchiara (UCSC) and N. R. Tanvir (U. Leicester) 
report on behalf of a larger collaboration:

On May 11.511 UT (~45 minutes after the Swift trigger)
we observed the optical counterpart of GRB 130511A
(Krimm et al. GCN 14620) with the GMOS spectrograph
mounted on the Gemini-North telescope.

The observation consists of 2x900s exposures
using the B600 grating and covers the 5100-7900
Angstroms wavelength range.

The resulting spectrum presents several absorption lines, 
including FeII(2344,2382,2374,2600), FeII*(2338,2349), 
FeI2463, MnII(25762594), MgII doublet (2796,2803A), and 
MgI2853 at the common redshift of z=1.3033.

We therefore propose this as the redshift of GRB 130511A.

We thank the Gemini staff for performing this
observation, in particular Tom Geballe.


GRB_name: GRB130511A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14622
SUBJECT: GRB 130511A: Enhanced Swift-XRT position
DATE:    13/05/11 14:20:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1521 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130511A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 196.64526, +18.70977 which is equivalent
to:

RA (J2000): 13h 06m 34.86s
Dec (J2000): +18d 42' 35.2"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130511A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14623
SUBJECT: GRB 130511A:  Upper limit by Xinglong TNT optical observation
DATE:    13/05/11 15:14:12 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L. P. Xin, J. Y. Wei, Y. L. Qiu,  J. Wang, 
J. S. Deng, C. Wu, X. H. Han  report on behalf of EAFON team:

We began to observe the field of GRB 130511A  (Krimm et al. GCN 14620)
using  80cm TNT telescope located at Xinglong observatory, China,
at 41.9 min after the burst on 12:12:41 UT, May 11th, 2013.    
15*300sec R-band images was obtained.  

The reported optical counterpart (Krimm et al. GCN 14620;  Cucchiara et a. GCN 14621)  
was not detected in all single images and the combined image,  
down to the upper limit of R~19.6 mag calibrated by USNO B1.0 R2 mag,
 at the mean time of  62.3 min after the trigger time. 

This message may be cited.


GRB_name: GRB130511A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14624
SUBJECT: GRB 130511A, Swift-BAT refined analysis
DATE:    13/05/11 21:27:10 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU),T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+950 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130511A (trigger #555600)
(Krimm, et al., GCN Circ. 14620).  The BAT ground-calculated position is
RA, Dec = 196.654, 18.709 deg which is
    RA(J2000)  =  13h 06m 36.9s
    Dec(J2000) = +18d 42' 33.7"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.

The mask-weighted light curve shows an initial sharp double-peak at T0
of duration ~0.5 seconds, transitioning to a FRED-like decay lasting ~5
seconds, after which the light curve returns to baseline.
T90 (15-350 keV) is 5.43 +- 2.22 sec (estimated error including systematics).

The time-averaged spectrum from T-0.07 to T+6.03 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.31.  The fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.09 sec in the 15-150 keV band
is 1.3 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555600/BA/


GRB_name: GRB130511A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14625
SUBJECT: GRB 130511A: MITSuME Okayama upper limits
DATE:    13/05/11 23:20:56 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of MITSuME and OISTER collaboration:

We observed the field of GRB 130511A (Krimm et al., GCNC 14620)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-05-11 12:01:00 UT (~30 min after the burst).
We did not find any new point source within the enhanced XRT error circle
(Osborne et al., GCNC 14622) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.16126    15:23:00    5940.0   >20.7  >20.7  >19.8
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB130511A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14626
SUBJECT: GRB 130511A: Kanata/HOWPol optical observation
DATE:    13/05/12 04:34:23 GMT
FROM:    Koji Kawabata at HASC,Hiroshima U  <kawabtkj@hiroshima-u.ac.jp>

K. Takaki, K. Kawaguchi, K. S. Kawabata, M. Ohno and M. Yoshida 
(Hiroshima Univ.) report on behalf of Kanata team:

We performed optical observations of GRB 130511A (Krimm et al., GCN 14620)
with HOWPol attached to the 1.5-m Kanata telescope at Higashi-Hiroshima
Observatory, Japan. The observation started at 11:32 UT on 2013 May 11 
with imaging-polarimetry mode, followed by observation with imaging mode 
after 12:10 UT. We detected the optical afterglow of the GRB.

Photometric results are shown below. We calibrated the Rc magnitude using
USNO-B1.0 R2 magnitudes of nearby stars. Our result seems to be consistent 
with the brightness upper-limits reported in Xin et al. (GCN 14623) and 
Kuroda et al. (GCN 14625). The decline rate between these two epochs can 
be approximated by a single power-law with an index of -0.7.

Mid time from  Total Exp   Filter    Magnitude
trigger (s)    (s)
-------------------------------------------------
2571            300x2        Rc    20.0+-0.1
8768            300x2        Rc    21.0+-0.2
-------------------------------------------------

This message may be cited.


GRB_name: GRB130511A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14627
SUBJECT: GRB 130511A: Swift-XRT refined Analysis
DATE:    13/05/12 07:42:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), V. D'Elia
(ASDC), A. Maselli  (INAF-IASFPA), V. Mangano (INAF-IASFPA), M.C. Stroh
(PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), J.P. Osborne (U.
Leicester) and H.A. Krimm report on behalf of the Swift-XRT team:

We have analysed 8.4 ks of XRT data for GRB 130511A (Krimm  et al. GCN
Circ. 14620),  from 57 s to 36.5 ks after the  BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Goad et al. (GCN. Circ 14622).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.99 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.03 (+0.20, -0.19). The
best-fitting absorption column is  1.1 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.6 x 10^-11 (4.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.1 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 3.5 sigma
Photon index:      2.03 (+0.20, -0.19)

If the light curve continues to decay with a power-law decay index of
0.99, the count rate at T+24 hours will be 2.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.4 x
10^-14 (1.2 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555600.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130511A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14628
SUBJECT: GRB130511A: SOAO Optical Observation
DATE:    13/05/12 15:16:58 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

M. Im (CEOU/SNU), H.-I. Sung (KASI), & Y. Urata (NCU)
on behalf of a larger collaboration

We observed GRB 130511A (Krimm et al., GCN 14620) 
in BVRI filters using a 0.6m telescope at the Sobaeksan
Optical Astronomy Observatory (SOAO), starting at 76min 
after the BAT alert.

In stacked images of 6 x 300sec exposures, we identify
the optical afterglow with the following magnitude
(Cucchiara et al. GCN 14621; Takaki et al. GCN 14626),
calibrated against a USNO-B1 star in the vicinity.

   T(mid, UT)         Mag
05-11 13:50:12     R=20.78 +- 0.13

The afterglow is detected in the other bands, but at
a lower S/N.

We thank the staffs at SOAO for performing the observation.


GRB_name: GRB130508A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14629
SUBJECT: GRB130508A: MASTER-Net optical observations
DATE:    13/05/13 07:13:31 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, 
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko, A.Sankovich
Sternberg Astronomical Institute, Moscow State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was pointed to the  GRB130508A 37 sec after notice time 
and 119 sec after GRB time at 2013-05-08 17:10:52.959 UT. On our first 
(20s exposure) set we haven't found optical transients within SWIFT 
error-box (Holland et al. GCN14607).
The 5-sigma upper limit has been about 17.3 mag
The message may be cited.


GRB_name: GRB130513A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14630
SUBJECT: GRB 130513A:  a long GRB detected by INTEGRAL
DATE:    13/05/13 09:10:32 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

S.Mereghetti (IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, 
P.Bordas (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of the 
IBAS Localization Team report:

a gamma ray burst lasting about 50 s has been detected by IBAS in the 
IBIS/ISGRI data at 07:38:00 UT of May 13.


The refined coordinates (J2000) are:

R.A.=  144.77525 deg
DEC.=   -5.24393  deg

with an uncertainty of 2 arcmin (90% c.l.).

The burst had a peak flux of 0.7 counts/cm2/s (20-200 keV, 1-s integration 
time) and a fluence in the same energy range of about 1e-6 erg/cmq.

A plot of the light curve will  be posted at 
http://ibas.iasf-milano.inaf.it/IBAS_Results.html


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14631
SUBJECT: GRB 130427A: Tautenburg 2nd epoch: No break, no clear SN
DATE:    13/05/14 02:39:21 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann, B. Stecklum, and C. Hoegner (TLS Tautenburg) report:

We observed the optical afterglow position (Elenin et al., GCN 14450) of
GRB 130427A (Maselli et al., GCN 14448) with the 1.34m Schmidt telescope
of the Thueringer Landessternwarte Tautenburg equipped with the 2k CCD
camera under good weather conditions. We obtained 3 x 600 sec frames in
the Rc band. The afterglow is detected in each frame.

Using the nearby star given in Rumyantsev et al. (GCN 14582) and also used
in our first epoch observations (Kann et al., GCN 14592), we derive a
preliminary magnitude of Rc = 20.37 +/- 0.07 at 15.54806 days after the
GRB.

This magnitude is only insignificantly fainter than the one we derived in
the first epoch, evidencing a clear flattening (see also Xu et al., GCN
14597). The host galaxy is expected to have about 21st magnitude in Rc
(Vega) following r' = 21.26 from SDSS (see, e.g., Watson et al., GCN
14606). Subtracting this magnitude from our detection yields a magnitude
for the optical transient of ~ 21.2 +/- 0.2.  This value agrees well with
an extrapolation of the earlier slope, implying that no further break has
occurred in the optical light curve (in agreement with the X-ray decay,
which shows a very similar slope). This implies either that the post-jet
break decay is among the most shallow known, or that a jet break has still
not occurred, pushing GRB 130427A further into the territory of hyper-
luminous events (Fan et al., arXiv:1305.1261, though see Laskar et al.,
arXiv:1305.2453).

The situation concerning a rising supernova is still unclear. Xu et al.
(GCN 14597) claimed a host-independent flattening and spectral change,
which was afterwards disputed on photometric (Watson et al., GCN 14606;
Perley & Tang, GCN 14615) and spectroscopic (Garnavich, GCN 14605; Perley
& Tang, GCN 14615) grounds. Our measurement offers no solution to this
conundrum, but it is possible that the SN, even if as luminous as SN
1998bw, will peak at a magnitude significantly fainter than the host
galaxy and afterglow (Ruffini et al., GCN 14526), making detection more
difficult than even in the case of GRB 030329/SN 2003dh.

We wish to thank T. Kruehler for discussions relating to the host galaxy.

This message may be cited.


GRB_name: GRB130514A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14632
SUBJECT: GRB 130514A: Swift detection of a burst
DATE:    13/05/14 07:29:58 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Sonbas (NASA/GSFC/Adiyaman Univ.), V. D'Elia (ASDC),
P. A. Evans (U Leicester), K. L. Page (U Leicester) and
D. Palmer (LANL), R. L. C. Starling (U Leicester) report on behalf of the Swift Team:

At 07:13:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130514A (trigger=555821).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 296.274, -7.956 which is 
   RA(J2000) = 19h 45m 06s
   Dec(J2000) = -07d 57' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of at least 180 sec.  The peak count rate
was ~3200 counts/sec (15-350 keV), at ~10 sec after the trigger. 

The XRT began observing the field at 07:15:09.9 UT, 88.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 296.28055, -7.97808 which
is equivalent to:
   RA(J2000)  = 19h 45m 07.33s
   Dec(J2000) = -07d 58' 41.1"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 82 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 7.65
x 10^20 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 5.83e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 97 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.23. 

Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130514A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14633
SUBJECT: GRB 130514A: P60 Observations
DATE:    13/05/14 08:39:21 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration:

The Palomar 60-inch telescope automatically responded to GRB 130427A 
(Sonbas et al., GCN 14632) and slewed to the position as soon as the 
source became observable a few minutes after the GRB alert.  A series of 
r, i, and z-band exposures was taken at very high airmass (~4) starting 
at 07:25:33 UT, 11.85 minutes after the BAT trigger.

The field is crowded, and contains a small globular cluster (GCl 114) 
centered at RA=19:45:14.40 Dec=-08:00:26.0 (J2000), 2.5 arcminutes from 
the GRB.

We do not detect any source at a position coincident with the XRT 
position in individual images.  A stack of the first five r-band images 
(spanning from 12-27 minutes after the GRB) shows no clear object at 
this position to a limiting magnitude of R > 19.6 mag (3 sigma), 
although there is a marginal detection of a source inside the error 
circle slightly below this level, centered at RA=19:45:07.27, 
Dec=-07:58:42.3 (J2000, +/-1.5 arcsec).  It is also apparent in similar 
r- and z-band stacks, and so is probably real.  The source may also be 
marginally present in the DSS imaging, although it is not in the USNO 
B1.0 catalog.

The association of the GRB with the globular cluster (or the optical 
source) is unclear; this could be an unusual Galactic event or a chance 
alignment of an ordinary extragalactic GRB (with a faint optical 
afterglow) with these objects. Further observations are encouraged.


GRB_name: GRB130514A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14634
SUBJECT: GRB 130514A: GROND optical-NIR afterglow discovery and photo-z
DATE:    13/05/14 08:40:11 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

S. Schmidl, D. A. Kann (both TLS Tautenburg) and J. Greiner (MPE Garching)
report on behalf of the GROND team:

We observed the field GRB 130514A (Swift trigger 555821; E. Sonbas et al.,
GCN 14632) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started at 07:15:31 UT on May 14th, 2 minutes after the SWIFT
BAT trigger. They were performed at an average seeing of 1" and at an
average airmass of 1.18.

Inside the 2".6 refined XRT error circle, we detect a source not visible
in the DSS or SDSS in all 7 bands. The GROND position for this source is:

RA (J2000)   =  19:45:07.90
Dec.(J2000)  = -07:58:34.4

with an uncertainty of 0".3.

Based on the first  4 min of total exposure we estimate preliminary
magnitudes (all in AB system) of

g' =  22.17 +- 0.09,
r' =  19.98 +- 0.01,
i' =  19.18 +- 0.02,
J  =  17.87 +- 0.03,
H  =  17.26 +- 0.03 and
K  =  16.81 +- 0.03

We propose this source to be the afterglow of GRB 130514A. Additional
evidence is the power-law shape of the SED.

The source shows a strong g'-band dropout, we derive a photometric
redshift of z = 3.6 +/- 0.2, with an additional small line-of-sight
extinction by SMC dust.

Given magnitudes are calibrated against SDSS as well as 2MASS field stars
and are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.23 mag in the direction of the
burst (Schlegel et al. 1998).


GRB_name: GRB130513A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14635
SUBJECT: GRB 130513A: Swift-XRT detection of the afterglow.
DATE:    13/05/14 08:42:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) and F. E. Marshall (NASA/GSFC) report on
behalf of the Swift-XRT team:

We have analysed 3.9 ks of XRT data for the INTEGRAL-detected burst:
GRB 130513A (Mereghetti et al., GCN 14630), from 25.4 ks to 37.2 ks
after the  INTEGRAL trigger. The data are entirely in Photon Counting
(PC) mode.  An X-ray source is detected within the INTEGRAL error
circle. Using 2486 s of PC mode data and 2 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 144.76167, -5.24171
which is equivalent to:

RA (J2000): 09h 39m 02.80s
Dec(J2000): -05d 14' 30.1"

with an uncertainty of 2.7 arcsec (radius, 90% confidence). This
position is 49 arcsec from the INTEGRAL position.  

The source is fading, and the light curve can be modelled with a
power-law of index 3.3 (+1.1, -0.45). We therefore conclude that it is
the afterglow of the GRB.

We detect only 24 photons from this source, so the spectrum is poorly
constrained. The photon index is 2.9 (+2.1, -1.1); the absorption is
consistent with the Galactic value of 3.4e20 cm^-2 (Kalberla et al.
2005) however within the errors on the spectral fit, could be as high
as 5e21 cm^-2.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020274.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130514A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14636
SUBJECT: GRB 130514A: Swift-BAT refined analysis
DATE:    13/05/14 12:33:26 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+723 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130514A (trigger #555821)
(Sonbas, et al., GCN Circ. 14632).  The BAT ground-calculated position is
RA, Dec = 296.278, -7.974 deg, which is 
   RA(J2000)  =  19h 45m 06.8s 
   Dec(J2000) = -07d 58' 26.1" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
 
The mask-weighted light curve shows two peaks, the first starting at ~T-20 sec,
peaking at ~T+12 sec, and returning almost to baseline at ~T+80 sec.
The second peak starts at ~T+80 sec, peaks at ~T+115 sec, and ends at ~T+380 sec.
T90 (15-350 keV) is 204 +- 13 sec (estimated error including systematics).
 
The time-averaged spectrum from T-7.09 to T+258.01 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.05.  The fluence in the 15-150 keV band is 9.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+13.42 sec in the 15-150 keV band
is 2.8 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555821/BA/


GRB_name: GRB130514A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14637
SUBJECT: GRB 130514A: Enhanced Swift-XRT position
DATE:    13/05/14 12:33:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.

Using 1035 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 130514A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 296.28288, -7.97592 which is equivalent
to:

RA (J2000): 19h 45m 7.89s
Dec (J2000): -07d 58' 33.3"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130514B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14638
SUBJECT: GRB 130514B:  a long GRB detected by INTEGRAL
DATE:    13/05/14 14:56:00 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

S.Mereghetti (IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, 
E.Filippova (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of 
the IBAS Localization Team report:

a gamma ray burst lasting about 10 s has been detected by IBAS in the 
IBIS/ISGRI data at 13:26:32 UT of May 14.

A preliminary analysis gives the coordinates (J2000)

R.A.=  147.604 deg
DEC.=  -18.969 deg

with an uncertainty of 3 arcmin (90% c.l.).


The burst had a peak flux of about 1 counts/cm2/s (20-200 keV, 1-s 
integration time). Due to telemetry saturation we can only set a lower 
limit of 6x10^-7 erg/cmq on the fluence in the same energy range.

A plot of the light curve has been posted at 
http://ibas.iasf-milano.inaf.it/IBAS_Results.html


GRB_name: GRB130513A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14639
SUBJECT: GRB 130513A: GROND observations
DATE:    13/05/14 16:20:57 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

S. Schmidl, D. A. Kann (both TLS Tautenburg) and J. Greiner (MPE Garching)
report on behalf of the GROND team:

We observed the field GRB 130513A (INTEGRAL trigger 6842; Mereghetti et
al., GCN 14630) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started in twilight at 22:54:57 UT on May 13th, 15.3 hours
after the IBAS trigger. They were performed at an average seeing of 1".0
and at an average airmass of 1.1.

Inside the 2".7 refined XRT error circle (Evans et al., GCN 14635), we do
not detect any sources. Based on an observation with 1500 s integration
time in g'r'i'z' and 1200 s integration time in JHK, centered at 0.6959
days after the trigger, we estimate preliminary 3-sigma upper limits (all
in AB system) of

g' > 25.4,
r' > 24.9,
i' > 24.2,
z' > 23.9,
J  > 21.4,
H  > 20.6 and
K  > 20.2.

We note that if the XRT source is indeed the afterglow, then it is very
faint optically. Galactic extinction is negligible.

Given magnitudes are calibrated against GROND zero points (g'r'i'z') as
well as 2MASS field stars (JHK) and are not corrected for the expected
Galactic foreground extinction corresponding to a reddening of
E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB130514A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14640
SUBJECT: GRB 130514A: Swift/UVOT Upper Limits
DATE:    13/05/14 17:28:08 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and E. Sonbas (NASA/GSFC/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130514A
97 s after the BAT trigger (Sonbas et al., GCN Circ. 14632).
No optical afterglow consistent with the optical position
from GROND (Schmidl et al. GCN Circ. 14634)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            97          247          147         >21.3
u_FC               310          560          246         >20.4
white               97          960          281         >21.5
v                  639         2529           56         >18.7
b                  565          757           39         >19.1
u                  310          732          265         >20.5
w1                 688          708           19         >19.1
w2                2487         2507           19         >19.5

The magnitudes in the table are not corrected for the 
Galactic extinction due to the reddening of E(B-V) = 0.23 
in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB130513A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14641
SUBJECT: GRB 130513A: Swift/UVOT Upper Limits
DATE:    13/05/14 17:31:32 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) reports on behalf of the Swift team:

The Swift/UVOT began settled observations of the field of GRB 130513A
25261 s after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 14630).
No optical afterglow consistent with the XRT position
(Evans and Marshall GCN Circ. 14635) 
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) 
for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white            25885        32269         1218         >21.9
v                26510        32924         1267         >20.6
u                25261        37138         1399         >21.6

The magnitudes in the table are not corrected for the Galactic
extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB130513A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14642
SUBJECT: GRB 130513A: RATIR Optical and NIR Observations 
DATE:    13/05/14 18:05:39 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB),
Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We observed the field of GRB 130513A (Mereghetti, et al., GCN Circular
14630) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronmico Nacional on Sierra San Pedro Mrtir from 2013/05 14.15 to
2013/05 14.16 UTC (19.97 to 20.30 hours after the BAT trigger),
obtaining a total of 0.18 hours exposure in the r' and i' bands and 0.07
hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (Evans & Marshall, GCN
Circular 14635), in comparison with USNO-B1 and 2MASS, we obtain the
following upper limits (3-sigma):

 r' > 22.64
 i' > 22.65
 Z > 21.34
 Y > 20.65
 J > 20.26
 H > 19.71

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro 
Mrtir.


GRB_name: GRB130514A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14643
SUBJECT: GRB 130514A: RATIR Optical and NIR Observations 
DATE:    13/05/14 18:13:06 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB),
Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), JosÃ© A. de Diego (UNAM), Leonid Georgiev (UNAM),
JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Neil Gehrels (GSFC),   
and Harvey Moseley (GSFC) report:

We observed the field of GRB 130514A (Sonbas et al., GCN 14632) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2013/05 14.30 to 2013/05 14.46 UTC (4.7 minutes
to 3.90 hours after the BAT trigger), obtaining a total of 2.49 hours
exposure in the r' and i' bands and 1.04 hours exposure in the Z,
Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with USNO-B1
and 2MASS, we obtain the following upper limits (3-sigma):

  r' > 23.51
  i' > 23.39
  Z  > 22.07
  Y  > 21.62
  J  > 21.43
  H  > 21.13

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

Schmidl et al. (GCN Circular 14634) report a source with r = 20.0 and i =
19.2 in images taken from 2 to 6 minutes after the BAT trigger. Perley
(GCN Circular 14633) reports a marginal detection in r and z in images
taken from 12 to 27 minutes after the BAT trigger. We began exposing on
this field less than 5 minutes after the BAT trigger, but due to the
high airmass of almost 5 and poor transparency on the south-eastern
horizon, our first useful images are not until about 17 minutes after
the trigger. The evolution of our 3-sigma limits is:

  i' > 21.72 at 0.49 hours after the trigger   
  i' > 22.48 at 1.14 hours
  i' > 23.00 at 1.59 hours
  i' > 23.17 at 2.02 hours
  i' > 23.24 at 2.60 hours
  i' > 23.30 at 3.34 hours
  i' > 23.39 at 3.90 hours

If we extrapolate the Schmidl et al. measurement of i = 19.2 at 4 minutes
according to t^-1, we would expect to have detected their source in our
observations out to 2 hours. That we did not suggests that light curve
fell faster than this. We note that quick-look light curve for Swift-XRT
falls by almost three orders of magnitude between about 3 minutes and 20
minutes, which may be consistent with a rapid optical decay.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.

[GCN OPS NOTE(14may13): Per author's request,"Kann et al" was changed
to "Schmidl et al", and the "approx equal" ISO-char symbols were replaced
with simple equal signs (=).]


GRB_name: GRB130514B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14644
SUBJECT: GRB130514B: MASTER-Net optical observations.
DATE:    13/05/14 18:37:30 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, 
N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko, A.Sankovich
Sternberg Astronomical Institute, Moscow State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was pointed to the  GRB130514B  90 sec  after GRB time 
but out first image were overlight by evening sky.
The first good image made 3812 sec after GRB time at 2013-05-14 14:30:06.562 UT. 
On our  first (180s exposure) good  set we haven't found optical transient 
within INTEGRAL error-box (S.Mereghetti et. al GCN 14638).
The 5-sigma upper limit has been about 16.5 mag
The observations mae on large zenith distance z=83 deg. 
The message may be cited.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14645
SUBJECT: GRB 130427A: optical observations
DATE:    13/05/14 20:23:42 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova (IKI), I. Korobtsev (ISTP), E. Klunko (ISTP), A. Pozanenko 
(IKI)  on behalf of  larger GRB  follow-up collaboration:

We continue observation of the Swift GRB 130427A (Maselli et  al., GCN 
14448)  with AZT-33IK telescope of Sayan observatory (Mondy). The 
afterglow (Elenin et al. GCN 14450, Perley GCN 14451) is clearly 
detected. The brightness of the afterglow+host  is following:

UT start,            t-t0       Filter Exp.   OT
                     (mid, days)        (s)    (mag.)

2013-05-13T15:20:00  16.3346   R      3600    20.66 +/- 0.06
2013-05-14T14:24:35  17.2968   R      3600    20.63 +/- 0.07

The photometry is based on the same star  reported by Rumyantsev et al. 
(GCN 14582). After subtraction  of a suggested brightness (R, Vega)of 
the host galaxy (e.g. Watson et al., GCN 14606; Kann et al., GCN 14631) 
from our photometric values, our light curve can be approximated (in 
general)  by a single power law   starting at ~ 0.6 days after burst 
trigger.  Indeed our early observations suggest some flattening between 
6.5 - 13 days (Xu et al., GCN 14597; Kann et al., GCN 14631). It could 
be due to a SN or due to a wide bump analogous to bumps observed early 
in the light curve.  However photometry is still preliminary and more 
detailed calibration/intercalibration is necessary.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14646
SUBJECT: GRB 130427A: Spectroscopic detection of the SN from the 10.4m GTC
DATE:    13/05/14 21:21:33 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Xu (DARK/NBI), 
G. Leloudas (OKC, Stockholm, DARK/NBI),  T. Kruehler, 
D. Malesani (DARK/NBI), J. Gorosabel (IAA-CSIC, UPV/EHU), Z. Cano (U. Iceland),
C.C. Thoene, R. Sanchez-Ramirez (IAA-CSIC), S. Schulze (PUC and MCSS), 
J.P.U. Fynbo, J. Hjorth (DARK/NBI), P. Jakobsson (U. Iceland) and 
A. Cabrera-Lavers (IAC-ULL) report on behalf of a larger collaboration:

We obtained spectroscopy of the optical counterpart and host galaxy of 
GRB 130427A (Maselli et al., GCN 14448; Elenin et al., GCN 14450) with the 
10.4m GTC telescope, 16.7 days after the GRB onset. This is 12.5 days in the 
host galaxy rest-frame (z = 0.34; Levan et al. GCN 14455, Xu et al. GCN 14478 
and Flores et al. GCN 1449). Observations consisted of 4x1200s with the 
R500R grism, covering the range between 4800 and 10000 AA with a 
resolution of ~600. The slit was oriented to cover both the afterglow and the 
host galaxy centre.

The spectrum has a strong contribution from the host galaxy. To overcome this, 
we built a synthetic host galaxy spectrum based on the SDSS (DR9) photometry 
using LePhare (version 2.2, Arnouts et al. 1999, MNRAS, 310, 540; Ilbert et al. 
2006, A&A, 457, 841). We then subtracted this host galaxy template from the 
GTC spectrum to obtain a "clean" spectrum of the counterpart associated to GRB 
130427A.

The resulting spectrum is that of a broad-lined Ic SN, with a prominent bump at 
~6800 A observer frame. In particular, we obtain an excellent match with the 
spectrum of  SN 2010bh at 12.7 (rest-frame) days after GRB 100316D 
(Bufano et al. 2012, ApJ 753, 67).

We stress that this conclusion is independent of the host galaxy model 
adopted. By running SNID (Blondin & Tonry 2007, ApJ, 666, 1024) on the 
original spectrum (i.e. including host contamination), we still obtain good 
matches with a series of broad-lined Type Ic SNe, including SNe 1998bw, 
1997ef, 2002ap and 2006aj, albeit at a lower redshift. The fact that SNID 
suggests a lower redshift  is explained by the fact that SN 2010bh had high 
expansion velocities, reaching ~34000 km/s at similar phases (Bufano et al. 
2012, ApJ 753, 67), which we suggest is also the case for the SN associated 
with GRB 130427A.

A figure of our preliminary analysis can be seen at:

http://www.iaa.es/~deugarte/GRBs/130427A/130427A_GTC.jpg

We acknowledge excellent support from the GTC staff.

[GCN OPS NOTE(14may13): Per author's request, ZCwas added to the author list.]


GRB_name: GRB130513A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14647
SUBJECT: GRB 130513A: Bassano Bresciano optical upper limit
DATE:    13/05/14 21:49:31 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs  <oabb@ulisse.bs.it>

U.Quadri, L.Strabla, R.Girelli and A.Quadri report:

We imaged the field of GRB 130513A (INTEGRAL trigger 6842; Mereghetti et
al., GCN 14630)  with the robotic telescope of (IAU station 565) 
Bassano Bresciano Observatory, Italy.

The observations started (after the dusk) 12h 19m after the 
GRB trigger, with our Schmidt telescope D=400 mm F/D=3 

Weather conditions were very good.

We co-added 2 series of 10 unfiltered CCD exposures of 120s each.

We did not found any optical counterpart in the 
Swift-XRT error circle (Evans & Marshall, GCN
Circular 14635) at our following limiting magnitude:
.

Start      End       Mlim
T0+        T0+
12.3h      13.0h     19.0


Magnitudes were estimated with the USNO-B1 cat. 
and are not corrected for galactic dust extinction.

The message may be cited.


GRB_name: GRB130514A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14648
SUBJECT: GRB 130514A: Skynet/PROMPT/DSO Detections
DATE:    13/05/15 00:28:06 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, A. Smith, D. Caton, L. 
Hawkins, T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. 
Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. 
Crain report:

Skynet observed the Swift/XRT localization of GRB 130515A (Sonbas et 
al., GCN 14632, Swift trigger #555821) with four 16" telescopes of the 
PROMPT array at CTIO, Chile and with the 14" telescope at the 
Appalachian State University Dark Sky Observatory (DSO) in Pisgah 
National Forest, North Carolina, starting at 2013-05-14, 07:14:32 UT, 
and continuing until 10:24 UT (t=51s-3.2h post-trigger). It took ~400 
exposures, ranging from 5s at early times to 160s at late times, 
simultaneously in each of the BVRI bands. We performed photometry on 
each exposure, calibrated to seven USNO-B1/NOMAD stars in the field.

We detect a fading afterglow at t=2-12m in the I band in unstacked 
images at the position reported by the GROND team (Schmidl, Kann & 
Greiner, GCN 14640), with I~17.4 at t=2m, fading with an approximate 
temporal index alpha~-1.2.  In stacked images, we obtain weak detections 
in R band at t=2.27m and 51m, and in V band at t=3.75m; both the R and 
the V band detections are ~1mag fainter than the I band light curve.  In 
B band, we obtain three weak detections from t=5m to 15m, all ~0.6mag 
fainter than the I band light curve.

A preliminary plot of our data is at:
http://skynet.unc.edu/grb/grb130514a.png

No further Skynet observations are scheduled.


GRB_name: GRB130514A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14649
SUBJECT: GRB 130514A: Swift-XRT refined Analysis
DATE:    13/05/15 01:30:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B.P. Gompertz (U. Leicester), A. Maselli  (INAF-IASFPA), V. Mangano
(INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU), J.A. Kennea
(PSU), M.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and E. Sonbas report on behalf of the Swift-XRT team:

We have analysed 8.5 ks of XRT data for GRB 130514A (Sonbas  et al. GCN
Circ. 14632),  from 95 s to 37.1 ks after the  BAT trigger. The data
comprise 405 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Osborne et al. (GCN. Circ 14637).

The late-time light curve (from T0+5.8 ks) can be modelled with  a
power-law decay with a decay index of alpha=1.15 (+0.13, -0.12).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.82 (+/-0.03). The
best-fitting absorption column is  3.14 (+0.13, -0.12) x 10^21 cm^-2,
in excess of the Galactic value of 7.6 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.99 (+0.20, -0.19)
and a best-fitting absorption column of 1.4 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.7 x 10^-11 (5.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.4 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: 2.1 sigma
Photon index:      1.99 (+0.20, -0.19)

If the light curve continues to decay with a power-law decay index of
1.15, the count rate at T+24 hours will be 9.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x
10^-13 (4.5 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555821.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130515A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14650
SUBJECT: GRB 130515A: Swift detection of a short burst
DATE:    13/05/15 01:35:00 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC),
N. Gehrels (NASA/GSFC), D. Grupe (PSU), S. T. Holland (STScI),
J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), C. A. Swenson (PSU),
T. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report on behalf of the
Swift Team:

At 01:21:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130515A (trigger=555880).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 283.422, -54.281 which is 
   RA(J2000) = 18h 53m 41s
   Dec(J2000) = -54d 16' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single
short peak with a duration of about 0.6 sec.  The peak count rate
was ~13000 counts/sec (15-350 keV), at ~0.1 sec after the trigger. 

The XRT began observing the field at 01:22:32.9 UT, 75.2 seconds after
the BAT trigger. Using promptly downlinked data we find a faint uncatalogued
X-ray source with an enhanced position: RA, Dec 283.4405, -54.2794
which is equivalent to:
   RA(J2000)  = 18h 53m 45.72s
   Dec(J2000) = -54d 16' 45.9"
with an uncertainty of 3.1 arcseconds (radius, 90% containment). This
location is 39 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 5.79
x 10^20 cm^-2 (Kalberla et al. 2005). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 78 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.07. 

Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB130514B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14651
SUBJECT: GRB 130514B: Swift-XRT Observations
DATE:    13/05/15 02:12:20 GMT
FROM:    Binbin Zhang at PSU  <bbzhang@psu.edu>

B.-B. Zhang (PSU), Dirk Grupe (PSU) and D. Malesani (DARK/NBI)  report  on
behalf of the Swift-XRT team:

We have analyzed 2.0 ks of XRT data for the INTEGRAL-detected burst:
GRB 130514B,  from 5.0 ks to 10.8 ks after the INTEGRAL trigger. The
data are entirely in Photon Counting (PC) mode.  An X-ray source is
detected within the INTEGRAL error circle. Using 1475 s of PC mode data
and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 147.60859, -18.96517 which is equivalent to:

RA (J2000): 09h 50m 26.06s
Dec(J2000): -18d 57' 54.6"

with an uncertainty of 1.8 arc sec (radius, 90% confidence). This
position is 37 arcsec from the INTEGRAL position. 

The X-ray source was detect with a peak count rate of 0.31 count/s 
at ~ T0+5359s, where T0= 2013 May 14 at 13:26:29.510 UT, then faded
to a count rate of 0.11 count/s at T0+11 ks.


A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.17 (+0.31, -0.30). The
best-fitting absorption column is  3.6 (+1.2, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 3.6 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.9 x 10^-11 (7.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.6 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:      2.17 (+0.31, -0.30)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020275.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB130511A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14652
SUBJECT: GRB 130511A: SSO 2.3m observation
DATE:    13/05/15 02:34:36 GMT
FROM:    Fang Yuan at ANU  <yuanfang@mso.anu.edu.au>

F. Yuan, M. Childress, S. Rapoport, B. Schmidt, M. Dopita (Australian National University) and J. Scharwachter (Observatoire de Paris)

We observed the field of GRB 130511A (Krimm et al., GCN 14620) using the Wide Field Spectrograph (WiFeS) on the ANU 2.3m. Three 900s integration at resolution R=3000, covering 540 - 950nm, were obtained starting at 2013-05-11 12:03 UTC, ~32 minutes after the Swift trigger.

Spectral photometry of the sky-subtracted data cube was carried out in a 6" diameter aperture. Compared to a nearby field star, we measure the optical afterglow to be at r ~ 20.2 and i ~ 20.1 at a mean time of ~ 1 hr after the burst.
We thank Tiantian Yuan, Fred Vogt and Rebecca Davis for performing this observation.


GRB_name: GRB130515A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14653
SUBJECT: GRB 130515A: VLT acquisition observation
DATE:    13/05/15 04:39:26 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

Dong Xu (DARK/NBI), Andrew J. Levan (Univ. Warwick), Nial R. Tanvir
(Univ. Leicester), Daniele Malesani (DARK/NBI), Johan P. U. Fynbo
(DARK/NBI), Steve Schulze (PUC and MCSS), report on behalf of the
X-shooter GRB GTO collaboration:

We observed the field of the short GRB 130515A (Malesani et al., GCN
14650) with the ESO VLT equipped with X-shooter.

In a 30-s acquisition image taken in the R band starting at 2:49 UT
(1.46 hr after the GRB), we detect a single source S1 consistent with
the best currently available XRT position
(http://www.swift.ac.uk/xrt_positions/), at coordinates (J2000):

(S1)

RA = 18:53:45.82
Dec = -54:16:46.9

This source has a magnitude R ~ 21.2, and can be faintly glimpsed in
the DSS red. At the present time, we cannot assess its relation to the
GRB, though it may be the host galaxy.

We also note the presence of two further objects S2 and S3 just
outside the XRT error circle, which can also be seen in the DSS, at
coordinates:

(S1)
RA = 18:53:45.26
Dec = -54:16:44.3

(S2)
RA =  18:53:46.16
Dec = -54:16:41.1

We acknowledge excellent and prompt support from the observing staff
at Paranal, in particular Grant Tremblay.


GRB_name: GRB130515A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14654
SUBJECT: GRB 130515A: Enhanced Swift-XRT position
DATE:    13/05/15 05:59:47 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 719 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130515A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 283.44011, -54.27906 which is equivalent
to:

RA (J2000): 18h 53m 45.63s
Dec (J2000): -54d 16' 44.6"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB130515A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14655
SUBJECT: GRB 130515A: GROND Observations
DATE:    13/05/15 06:01:37 GMT
FROM:    Sebastian Schmidl at TLS Tautenburg  <schmidl@tls-tautenburg.de>

S. Schmidl, D. A. Kann (both TLS Tautenburg) and J. Greiner (MPE Garching)
report on behalf of the GROND team:

We observed the field of the short GRB 130515A (Swift trigger 555880;
Malesani et al., GCN 14650) simultaneously in g'r'i'z'JHKs with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO
telescope at La Silla Observatory (Chile).

Observations started as soon as the position became visible above the
pointing limit, at 02:12:08 UT on May 15th, 51 minutes after the BAT
trigger. They were performed at an average seeing of 1".6 and at an
average airmass of 2.4.

Inside the 2".9 SPER XRT error circle (RA = 18:53:45.79, Dec.
-54:16:45.2), we detect a faint source, and additionally a significantly
brighter, possibly extended source on the western edge of the XRT error
circle.

We find the following positions (J2000) for these sources:
In the error circle: RA = 18:53:45.79, Dec. = -54:16:47.3
On the western edge: RA = 18:53:45.24, Dec. = -54:16:44.5
with an error of 0".5 in each case.

Based on an observation with 780 s integration time in g'r'i'z' and 720 s
integration time in JHK, centered at 0.043586 days after the trigger, we
estimate preliminary magnitudes 3-sigma upper limits (all in AB system) of

g' > 23.86,
r' = 22.55 +/- 0.15,
z' = 21.17 +/- 0.11,
J  = 19.74 +/- 0.27,
H  > 19.4 and
K  > 19.1

for the object inside the error circle, and

g' = 22.12 +/- 0.08.,
r' = 20.68 +/- 0.03.,
z' = 19.51 +/- 0.03.,
J  = 18.50 +/- 0.09,
H  = 18.45 +/- 0.14 and
K  = 18.47 +/- 0.17

for the possible galaxy on the western edge.

Given magnitudes are calibrated against GROND zero points (g'r'i'z') as
well as 2MASS field stars (JHK) and are not corrected for the expected
Galactic foreground extinction corresponding to a reddening of
E_(B-V)=0.07 mag in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB130515A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14656
SUBJECT: GRB 130515A: Gemini/GMOS Observations
DATE:    13/05/15 06:32:58 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>

S. B. Cenko (UC Berkeley), A Cucchiara (UCSC), D. Xu (DARK/NBI), and A. J.
Levan (U. Warwick) report on behalf of a larger collaboration:

We obtained a single 240 s r'-band image of the field of GRB 130515A
(Malesani et al., GCN 14650) with the Gemini Multi-Object Spectrograph
mounted on the 8 m Gemini South telescope.  The observation commenced at
01:59 UT (~ 38 min after the Swift trigger) under poor seeing conditions.

We identify the same 3 sources in the vicinity of the XRT error circle as
Xu et al. (GCN 14653).  For reference, we measure J2000 positions for
these sources with respect to nearby point sources from the 2MASS catalog
to be:

S1: 18:53:45.79, -54:16:47.1

S2: 18:53:45.23, -54: 16:44.4

S3: 18:53:46.13, -54:16:41.2

We have compared photometry from our Gemini images directly with that
obtained by the VLT approximately 50 minutes later. For these three point
sources, we measure the following change in magnitude (VLT - Gemini):

S1: -0.37 +/- 0.18 mag

S2: -0.03 +/- 0.10 mag

S3: -0.03 +/- 0.10 mag

There is this marginal evidence that S1 has brightened between the two
epochs.  However, we cannot rule out that the discrepancy results from a
color difference between the two images (r' vs R).

Further observations are planned.

[GCN OPS NOTE(15may13): Per author's request, the 14653 reference was
corrected to "Xu et al".]


GRB_name: GRB130514B
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14657
SUBJECT: GRB 130514B: GROND observations
DATE:    13/05/15 10:58:01 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

S. Schmidl, D. A. Kann (both TLS Tautenburg) and J. Greiner (MPE Garching)
report on behalf of the GROND team:

We observed the field GRB 130514B (INTEGRAL trigger 6843; Mereghetti et
al., GCN 14638) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started in late twilight at 23:11:33.7 UT on May 14th, 9.75
hours after the IBAS trigger. They were performed at an average seeing of
1".6 and at an average airmass of 1.0.

Inside the 1".8 refined XRT error circle (Zhang et al., GCN 14561), we do 
not detect any sources. Based on an observation with 1500 s integration
time in g'r'i'z' and 1200 s integration time in JHK, centered at 0.42572
days after the trigger, we estimate preliminary 3-sigma upper limits (all
in AB system) of

g' > 24.7,
r' > 24.4,
J  > 21.0,
H  > 20.7 and
K  > 20.0.

Optically, this GRB is again very faint, similar to GRB 130513A (Schmidl
et al., GCN 14639). Galactic extinction is negligible. The XRT spectrum
shows strong absorption (Zhang et al., GCN 14561), and this is probably
dark GRB.

Given magnitudes are calibrated against GROND zero points (g'r'i'z') as
well as 2MASS field stars (JHK) and are not corrected for the expected
Galactic foreground extinction corresponding to a reddening of
E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB130515A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14658
SUBJECT: GRB 130515A: Swift-BAT refined analysis
DATE:    13/05/15 11:57:33 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. Malesani (DARK/NBI),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130515A (trigger #555880)
(Malesani, et al., GCN Circ. 14650).  The BAT ground-calculated position is
RA, Dec = 283.436, -54.283 deg, which is 
   RA(J2000)  =  18h 53m 44.6s 
   Dec(J2000) = -54d 16' 57.3" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 69%.
 
The mask-weighted light curve shows two overlapping peaks starting
at ~T+0.00, peaking at ~T+0.00 and ~T+0.30, and ending at ~T+0.40 sec.
T90 (15-350 keV) is 0.29 +- 0.06 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.04 to T+0.33 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.77 +- 0.18.  The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/555880/BA/


GRB_name: GRB130514B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14659
SUBJECT: GRB 130514B Swift-BAT observations
DATE:    13/05/15 12:25:14 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. R. Cummings (UMBC/CRESST/GSFC) and H. A. Krimm (USRA/CRESST/NASA)
report on behalf of the Swift-BAT team:

At the time of the INTEGRAL GRB 130514B (Mereghetti et al. GCN Circ# 14638),
Swift was in a preplanned slew maneuver.  BAT photon event data was
collected during this slew.  BAT saves such "slew survey" data when possible
within telemetry constraints.  The source was detected in a mosaic image.
As seen in BAT, the burst was a single FRED peak about 7 +/- 1 seconds long.
The source had about 10% mask coding in the BAT detector plane.

The BAT spectrum is well-fit by a power-law function with a photon index
of 1.72 +/- 0.21.  The fluence from 15-150 keV in 8 seconds was
(8.8 +/- 0.6) x 10^-7 ergs/cm^2/sec.  Errors are 68% confidence.


GRB_name: GRB130515A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14660
SUBJECT: GRB 130515A: Swift/UVOT Upper Limits
DATE:    13/05/15 14:16:02 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL), M. De Pasquale (MSSL-UCL) and D. Malesani (DARK/NBI)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130515A
79 s after the BAT trigger (Malesani et al., GCN Circ. 14650).
In the intial UVOT exposures, we do not detect an optical afterglow consistent
with the refined XRT position (Beardmore et al. GCN Circ. 14654). We also do not
detect an optical source consistent with the positions of s1 and s2 reported by the VLT
(Xu et al. GCN Circ. 14653) and Gemini (Cenko et al., GCN Circ. 14656),
nor at the positions of the sources reported by GROND (Schmidl et al., GCN Circ. 14655).
However, we do marginally detect VLT s3 (Xu et al. GCN Circ. 14653) in white
at a magnitude of 21.59 +/- 0.39, which is also observed in the DSS.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures at the refined
XRT position are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            79          229          147         >21.2
u_FC               291          541          246         >20.2
white               79         6414          580         >21.7
v                  620         5388          236         >19.8
b                  546         6209          432         >21.0
u                  291         6003          659         >20.7
w1                 669         5798          413         >20.7
m2                 645         5592          236         >20.0
w2                 596         6603          415         >20.7

The magnitudes in the table are not corrected for the
Galactic extinction due to the reddening of E(B-V) = 0.07
in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB130515A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14661
SUBJECT: GRB 130515A: Swift-XRT refined Analysis
DATE:    13/05/15 16:11:31 GMT
FROM:    Binbin Zhang at PSU  <bbzhang@psu.edu>

B.-B. Zhang (PSU) and D. Malesani (DARK/NBI) report on behalf of the
Swift-XRT team:

We have analysed 8.1 ks of XRT data for GRB 130515A (Malesani  et al.
GCN Circ. 14650),  from 82 s to 34.1 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Beardmore et al. (GCN. Circ
14654). The source is fading with alpha >0.8.


If the light curve continues to decay with a power-law decay index of 0.8,
the count rate at T+24 hours will be 1.4 x 10^-4 count s^-1

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00555880.

This circular is an official product of the Swift-XRT team.

[GCN OPS NOTE(15may13):  Per author's request, the ).8" was added
to the end of the first line in the 2nd paragraph.]


GRB_name: GRB130427A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14662
SUBJECT: GRB 130427A: Skynet detections of a possible supernova
DATE:    13/05/15 17:02:50 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, K. McLin, L. Cominsky, 
A. Smith, D. Caton, L. Hawkins, B. Holmes, T. Linder, T. Berger, H. T. 
Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. 
Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:

Skynet has continued observing the Swift/XRT localization of GRB 130427A 
(Maselli et al., GCN 14448, Swift trigger #554620) with: four 16" 
telescopes of the PROMPT array at CTIO, Chile (BVRI bands); the 14" 
GLAST Optical Robotic Telescope (GORT) at the Hume Observatory in 
California (RcIc bands); the 14" Deep Sky Observatory (DSO-14) telescope 
at Pisgah National Forest, NC; and the 30" telescope at the Astronomical 
Research Observatory (ARO-30) in Westfield, IL. Our observations now 
span 18 nights, from t=0.65 to 17.6 days post-trigger. Skynet has taken 
3420 160-second exposures on the 4 PROMPT telescopes, 420 160-second 
exposures on GORT, 91 160s exposures on DSO-14 and 133 60-160s exposures 
on ARO-30, or a total of over 178 hours on source. We performed 
photometry on each exposure, calibrated to two SDSS stars in the field. 
We stacked exposures to improve sensitivity, in groups ranging from 3 
exposures on night 1, to 60 exposures on night 18.

In Trotter et al. (GCN 14608) we reported a flattening of the light 
curve at t~10 days.  That flattening has continued, with possible 
chromatic bumps in V, R and I bands at ~14d, 11d and 10d, respectively.  
Our most recent observations, at t=17.8d, show a rebrightening in V, R 
and I bands; we speculate that this may be the onset of the classical 
supernova, which was detected spectroscopically by de Ugarte Postigo et 
al. (GCN 14646) at t=16.7 days.

A preliminary light curve including all Skynet observations through 
t=17.8 days is at:
http://skynet.unc.edu/grb/grb130427a_17.png

Further observations are scheduled.


GRB_name: GRB130515A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14663
SUBJECT: GRB 130515A: Fermi GBM detection
DATE:    13/05/15 17:16:56 GMT
FROM:    Peter Jenke at MSFC  <peter.a.jenke@nasa.gov>

P. Jenke (UAH) reports on behalf of the Fermi GBM Team:

"At 01:21:17.88 UT on May 15 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130515A (trigger 390273680 / 130515056),
which was also detected by the Swift/BAT (Malesani et al., GCN Circ. 14650).
The GBM on-ground location is consistent with the Swift position.

The angle of the Fermi LAT boresight is 120 degrees from the Swift location.

The GBM light curve consists of a single pulse with a FRED-like shape
with a duration (T90) of about 0.26 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.256 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.90 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 450 +/- 100 keV.

The event fluence (10-1000 keV) in this time interval is
(10.4 +/- 0.5)E-07 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 22 +/- 2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB130514B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14665
SUBJECT: GRB 130514B: RATIR Optical and NIR Observations 
DATE:    13/05/15 19:03:13 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We observed the field of GRB 130514B (Mereghetti, et al., GCN 14638)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronmico Nacional on Sierra San Pedro Mrtir from 2013/05 15.15 to
2013/05 15.16 UTC (14.12 to 14.55 hours after the BAT trigger),
obtaining a total of 0.20 hours exposure in the r' and i' bands and 0.08
hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (Zhang et al., GCN
Circular 14651), in comparison with USNO-B1 and 2MASS, we obtain the
following upper limits (3-sigma):

 r' > 22.49
 i' > 21.95
 Z > 20.53
 Y > 20.54
 J > 19.66
 H > 19.72

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

Our non-detection is consistent with the deeper upper limits of Schmidl
et al. (GCN Circular, 14657) obtained a few hours earlier.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14666
SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations - Photometric Evidence for a New Component 
DATE:    13/05/16 01:57:40 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori
Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:

We have continued to monitor GRB 130427A with the Reionization and
Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold
Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San
Pedro Mrtir, obtaining homogenous photometry in griZYJH. We have
photometry for every night except 2013 May 6. On most nights our
photometric uncertainties in gri are about 2%.

As we reported earlier in Watson et al. (GCN Circular 14606), the
optical afterglow during the first day is well-fitted by a power law
with a temporal index of -1. However, around T+1d there is a break, and
the power law steepens. From T+2.5d to T+14.9d our gri photometry is
well-fitted by a power law with a temporal index close to -1.5 plus a
constant component consistent with the presumed SDSS host galaxy.

However, our observations at T+15.9d, T+16.9d, and T+17.9d are
systematically brighter than this fit. Adding a new component starting
at T+15.5d with zero colors and constant magnitude significantly
improves the fit (with a confidence level of better than 99.5%). The
constant component has

  g = r = i = 24.53  0.25.

We do not mean to suggest that the new component actually has zero color
or constant magnitude. However, at this moment our data cannot usefully
constrain anything other than a characteristic brightness.

Our data, model, and residuals are shown at

  https://dl.dropboxusercontent.com/u/528672/GCN/2013-05-16-GRB-130427A.pdf

Assuming a distance modulus of 41.26, the new component corresponds to
an absolute magnitude of -16.7  0.25. If the new component is a Type 1c
supernova, as suggested by de Ugarte Postigo et al. (GCN Circular
14646), we might expect the peak extinction-corrected absolute magnitude to be
around -18 (Drout et al. 2011, ApJ, 741, 97). Thus, depending on the
host galaxy extinction, we might be seeing this possible supernova at or just
before its peak.

We caution that the new component is currently about 2 magnitudes
fainter than the afterglow component, which at 18.0 days is predicted to
have

  i = 22.21  0.04

and even fainter then the galaxy, which is predicted to have

  i = 21.23  0.03.

The relative brightnesses of the new component, the fading afterglow,
and the host galaxy also have significant implications for unveiling the
spectrum of the possible supernova.

We further caution that from our data alone we cannot exclude the
possibility that the new component might simply be a significant
flattening of the late afterglow component.

The largest residuals of our observations from the model (with or
without the new component) are at the level of 0.05 magnitudes. We do
not see the large variations reported by Trotter et al. (GCN Circular
14662).

Further observations are planned.

We thank the staff of the Observatorio Astronmico Nacional in San Pedro
Mrtir.


GRB_name: GRB130515A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14667
SUBJECT: GRB 130515A: FORS2 spectroscopy of candidate counterpart
DATE:    13/05/16 09:04:17 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

A. J. Levan (U. Warwick)  and N. R. Tanvir (U. Leicester) report for a larger collaboration:

We observed the location of GRB 130515A (Malesani et al. GCN 14650) with VLT/FORS2, beginning at ~03:30 UT, 2 hours after the burst. At this epoch we obtained imaging and spectroscopy of the brightest source in the XRT error box (S1 in Xu et al. GCN 14653 and Cenko et al. GCN 14656). This spectrum exhibits several broad absorption features consistent with an M-dwarf star at z=0, indicating that it is not the host galaxy of GRB 130515A.

In fact, preliminary analysis of our imaging suggests that sources S2 and S3 referred to by Xu et al. and Cenko et al. are also consistent with being point-like.  The nearest evidently extended, and reasonably bright, source is a galaxy at position 18:53:45.01  -54:16:50.9, approximately 8 arcsec from the current enhanced X-ray position (http://www.swift.ac.uk/xrt_positions/00555880/).

We thank the staff at Paranal for their excellent support with these observations.


GRB_name: GRB130515A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14668
SUBJECT: Konus-Wind observation of GRB 130515A
DATE:    13/05/16 10:01:58 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P.
Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind
team report:

The short-duration GRB 130515A (Swift-BAT trigger #555880:
Malesani et al., GCN 14650, Barthelmy et al., GCN 14658;
Fermi-GBM detection: Jenke, GCN 14663)
triggered Konus-Wind at T0=04880.440s UT (01:21:20.440)

The burst light curve shows a single pulse
from ~T0-0.05 s to ~T0-0.2 s, with a total duration of ~0.25s.
The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB130515_T04880/

As observed by Konus-Wind, the burst had a fluence
of (1.1  0.2)x10-6 erg/cm2 and a 16-ms peak flux,
measured from T0-0.016 s, of (2.1  0.5)x10-5 erg/cm2
(both in the 20 - 1500 keV energy range).

Modelling the K-W 3-channel time-integrated spectrum
(from T0-0.064 s to T0+0.192 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = 0.0  0.4, and Ep = 410  90 keV

Modelling the K-W 3-channel spectrum at the maximum count rate
(from T0-0.064 s to T0)
by a power law with exponential cutoff model
yields alpha = -0.5  0.4, and Ep = 715  360 keV


All the quoted errors are at the 1 sigma confidence level.


GRB_name: GRB130427A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  14669
SUBJECT: GRB 130427A:: BTA spectroscopic observations on May 10/11.
DATE:    13/05/16 21:22:08 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

Vladimir V. Sokolov (SAO-RAS), Alberto J. Castro-Tirado (IAA-CSIC),
Alexander S. Moskvitin, Elena A. Barsukova, Viktoria N. Komarova, Nikolaj
V. Borisov, Azamat F. Valeev, Tatyana N. Sokolova (SAO-RAS) and Vitaly P.
Goranskij (SAI-MSU, SAO-RAS), report:

"We have obtained 3 epochs of spectroscopy for the GRB 130427A optical
afterglow (Maselli et al. GCNC 14448, Elenin et al. GCNC 14450) with the
6-meter BTA equipped with Scorpio. The spectra (with exposure times of
4 x 900 s, 5 x 900 s and 4 x 1200 s) were taken on May 2/3, 5/6 and
10/11 respectively. We used the VPHG 550G grating which covers the
3700-7900 A spectral range and provides a 13 A spectral resolution.

Narrow host galaxy lines such as 3727 A [OII], [OIII] 4959 A, 5007 A and
Balmer lines are noticeable in all spectra. The measured redshift is 0.3393,
in good agreement with the previously reported values (Levan et al. GCNC
14455; Xu et al. GCNC 14478; Flores et al. GCNC 14491; Garnavich GCNC 14605
and Perley & Tang, GCNC 14615). Particularly, we detect marginal excess
emission in the range 6000-7000 A on the later spectrum obtained on May
10/11, which can be interpreted as evidence of the underlying SN (de
Ugarte Postigo et al., GCNC 14646), what is also supported by the
long-term photometric observations (Trotter et al., GCNC 14662; Watson et
al., GCNC 14666).

Our preliminary flux-calibrated spectra can be seen at:

http://www.sao.ru/hq/grb/GRB130427A/GRB130427A_BTA_May2-10.jpg

We thanks S.N. Fabrika, O.P. Zhelenkova, Yu.Yu. Balega, V.V. Vlasyuk and
A.S. Moiseev for their help in obtaining the observations."


