# GCN_circulars

GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17487
SUBJECT: GRB 150222A: MASTER early  optical observations
DATE:    15/02/22 17:19:12 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

E. Gorbovskoy, V. Lipunov,  M.Pruzhinskaya, V.Kornilov, D.Kuvshinov,
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov,
D.Denisenko, A.Sankovich
Lomonosov Moscow State University,
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.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, Kourovka

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical 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 Tunka was pointed to the  GRB150222A  58 sec after notice time 
and 76 sec after trigger time at 2015-02-22 16:57:57 UT in two 
polarizations. On our first (10s 
exposure)  set we haven't found optical transient  within SWIFT error-box 
(Bernardini  et. al GCN 17486).
The 5-sigma upper limit has been about 15.5 mag
The observations  made on high zenith distance (z=75 d).
The message may be cited.


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17488
SUBJECT: GRB 150222A: Zadko observatory - Gingin optical observations
DATE:    15/02/22 20:32:04 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

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

We imaged the field of GRB 150222A detected by SWIFT
(trigger 632180) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 55s after the GRB trigger
(42s after the notice). The elevation of the field increased from
51 degrees above horizon and weather conditions
were very good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT at the XRT position
(Bernardini et al. GCNC 17486) with a limiting magnitude of:
t0+55s to t0+115s : Rlim = 18.5

The second image is 30.0s exposure in tracking mode:
t0+134s to t0+164s : Rlim = 19.8

We co-added a series of exposures:
t0+134s to t0+834s : Rlim = 21.5

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17489
SUBJECT: GRB 150222A: Mondy optical observations
DATE:    15/02/22 22:42:58 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev 
(ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB 150222A  (Bernardini  et al., GCN 17486) 
with AZT-33IK telescope of Sayan observatory (Mondy)  starting on Feb., 
22 (UT) 17:48:56. We obtained 37 images in R-filter of 120 s exposure. 
Within the Swift-XRT error circle (Bernardini  et al., GCN 17486) we 
marginally detected optical  source with a magnitude of R=22.15+/-0.25 
at 0.06201 days after trigger (mid time). Photometry of the source is 
based on nearby USNO-B1.0 (R2) stars. At this time we cannot confirm 
variability or fading nature of the source.


GRB_name: GRB150222A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17491
SUBJECT: GRB 150222A: Swift-BAT refined analysis
DATE:    15/02/23 01:16:22 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
M. G. Bernardini (INAF-OAB), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-60 to T+117 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150222A (trigger #632180)
(Bernardini, et al., GCN Circ. 17486).  The BAT ground-calculated position is
RA, Dec = 198.787, -12.151 deg which is
    RA(J2000)  =  13h 15m 09.0s
    Dec(J2000) = -12d 09' 02.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.

The mask-weighted light curve shows a double-peaked structure, with a first peak 
from T+0 to T+3 sec and a second, larger peak from T+3 to T+18 sec, followed by 
lower level emission out to ~T+40 sec.
T90 (15-350 keV) is 15.90 +- 7.32 sec (estimated error including systematics).

The time-averaged spectrum from T-0.14 to T+28.11 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.08.  The fluence in the 15-150 keV band is 2.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+5.62 sec in the 15-150 keV band
is 4.7 +- 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/632180/BA/


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17493
SUBJECT: GRB 150222A: TNG optical observations
DATE:    15/02/23 02:32:04 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), V. D'Elia (INAF/OAR and ASI/ASDC), P. D'Avanzo 
(INAF/OABr), A. Melandri (INAF/OABr), S. Covino (INAF/OABr), V. Lorenzi 
(INAF/TNG), Albar Garcia de Gurtubai Escudero (INAF/TNG), report on 
behalf of the CIBO collaboration:

We observed the field of GRB 150222A (Bernardini et al., GCN 17486) with 
the 3.6m TNG telescope equipped with the DOLoRes camera. Observations 
consisted of 4 images in the I band for a total of 20 min exposure. The 
seeing was poor (3.2").

No object is detected within the (currently unenhanced) XRT position, 
down to a limiting magnitude I > 22.3 (calibrated against nearby USNO 
stars). The mean time of the observation was 2015 Feb 23.055 UT, that is 
8.4 hr after the GRB.


GRB_name: GRB150222A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17494
SUBJECT: GRB 150222A: Enhanced Swift-XRT position
DATE:    15/02/23 04:13:26 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 3503 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 150222A, 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 = 198.78648, -12.15200 which is equivalent
to:

RA (J2000): 13h 15m 8.75s
Dec (J2000): -12d 09' 07.2"

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


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17495
SUBJECT: GRB 150222A: GROND optical afterglow candidate
DATE:    15/02/23 07:15:01 GMT
FROM:    Ana Nicuesa at TLS Tautenburg  <ana@tls-tautenburg.de>

A. Nicuesa Guelbenzu (TLS Tautenburg), P. Wiseman (MPE Garching), and J.
Greiner (MPE Garching) report:

We observed the field of GRB 150222A (Swift trigger 632180; Bernardini et
al., GCN 17486) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 03:39:15 UT on February 23, about 10 hours after
the GRB trigger. Inside the enhanced X-ray error circle (Beardmore et al.,
GCN 17494) we detect a faint source at coordinates RA, DEC (J2000) =
13:15:08.75, -12:09:06.2 with an error of 0".5.

At a mean time of February 23, at 04:39:07 UT, we measure the following
preliminary AB magnitude:


g' = 24.8 +/- 0.2.
r' = 24.6 +/- 0.3.

At present we cannot decide if this is the afterglow. Observations are
ongoing.

Magnitudes are calibrated against GROND zeropoints (g'r'i'z')
and are not corrected for the Galactic extinction
in the direction of the burst.


GRB_name: GRB150222B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17497
SUBJECT: GRB 150222B: MAXI/GSC detection
DATE:    15/02/23 11:08:51 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

T. Hori (Kyoto U.), H. Negoro (Nihon U.), M. Serino (RIKEN), 
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, 
Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Morii, 
J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, D. Uchida (Osaka U.), M. Nakajima, K. Fukushima, T. Onodera,
K. Suzuki, M. Fujita, F. Honda, T. Namba (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.) report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued
X-ray transient source at 05:24:16 UT on February 22.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (155.897 deg, -41.170 deg) = (10 23 35, -41 10 13) (J2000)
with a 90% C.L. statistical error of 0.39 deg and an additional 
systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 123 +- 26 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at 23:13 UT
on February 21 and in the next transit at 06:56 UT on February 22
with an upper limit of 20 mCrab for each.


GRB_name: GRB150222A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17498
SUBJECT: GRB 150222A: Swift-XRT refined Analysis
DATE:    15/02/23 11:26:27 GMT
FROM:    Maria Grazia Bernardini at INAF/Brera  <grazia.bernardini@brera.inaf.it>

C. Pagani (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M.
de Pasquale (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester) and M. G.
Bernardini (INAF-OAB) report on behalf of the Swift-XRT team:

We have analysed 6.7 ks of XRT data for GRB 150222A (Bernardini et al.
GCN Circ. 17486), from 76 s to 44.7 ks after the  BAT trigger. The data
comprise 221 s in Windowed Timing (WT) mode (the first 10 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 Beardmore
et al. (GCN Circ. 17494).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.95 (+/-0.03). Some flaring activity is observed 
between T+250 s and T+650 s.

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.51 (+0.12, -0.11). The
best-fitting absorption column is  4.7 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 3.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.45 (+0.19, -0.18)
and a best-fitting absorption column of 5.8 (+1.0, -0.9) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.4 x 10^-11 (7.9 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.8 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 10.0 sigma
Photon index:      2.45 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
0.95, the count rate at T+24 hours will be 9.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-13 (7.8 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/00632180.

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


GRB_name: GRB150222A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17499
SUBJECT: GRB 150222A: Swift/UVOT Upper Limits
DATE:    15/02/23 12:43:28 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and M. G. Bernardini (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150222A
96 s after the BAT trigger (Bernardini et al., GCN Circ. 17486).
No optical afterglow consistent with the XRT position (Beardmore et
al. GCN Circ. 17494) 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            96          246          147         >20.8
u_FC               308          558          246         >20.7
white               96         6906          746         >21.3
v                  639         5881          274         >19.9
b                  564         6702          452         >20.9
u                  308         6496          678         >20.8
w1                 689         6292          432         >20.0
m2                 836         6086          413         >20.4
w2                1019         6994          297         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17500
SUBJECT: GRB 150222A: I-band observations from OSN
DATE:    15/02/23 13:41:59 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

Antonio de Ugarte Postigo (IAA-CSIC, DARK/NBI), Christina Thoene (IAA-CSIC), 
and Victor Casanova (IAA-CSIC) report on behalf of a larger collaboration:

We observed the field of GRB 150222A (Bernardini et al., GCN 17486) with the 
1.5 m telescope at Sierra Nevada Observatory (Granada, Spain). 
Observations consisted of 34x300s in I-band and ranged from 2:46 to 5:44 UT 
(mid epoch at 4:15 UT, or 11.31 hr after the burst trigger). Observing conditions 
were poor, with a seeing of 2.9". We do not detect the optical counterpart 
candidate reported by Mazaeva et al. (GCN 17489) and Nicuesa Guelbenzu et al.
(GCN 17495) or any other object within the enhanced XRT error circle (Beardmore
et al. GCN 17494). The 3-sigma limit of the combined image is I(Vega) = 22.5 mag,
as compared with USNOB-1.0 stars.
 
Considering an optical decay slope of alpha ~ 1.1 (where F_nu ~ t^(-alpha)) 
between the epochs of Mazaeva et al. and Nicuesa Guelbenzu et al., and a typical 
GRB colour, our observation is consistent with the expected brightness and is also 
consistent with the non-detections reported by other groups (Ivanov et al. GCN 
17487; Klotz et al. GCN 17488; Malesani et al. GCN 17493; Kuin et al. GCN 17499)


GRB_name: GRB150220A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17501
SUBJECT: GRB 150220A: Swift ToO observations
DATE:    15/02/23 21:35:29 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the IPN GRB 150220A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020484

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the IPN event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150220A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17502
SUBJECT: IPN Triangulation of GRB 150220A
DATE:    15/02/24 15:29:11 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

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

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

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

A long-duration GRB 150220A has been observed by Fermi (GBM trigger 
446134898), Konus-Wind, Mars-Odyssey (HEND), and MESSENGER (GRNS), so 
far, at about 51696 s UT (14:21:36).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   135.496 (09h 01m 59s)  -1.597 ( -1d 35' 49")
  Corners:
   135.673 (09h 02m 42s)  -1.932 ( -1d 55' 54")
   135.354 (09h 01m 25s)  -2.064 ( -2d 03' 51")
   135.322 (09h 01m 17s)  -1.262 ( -1d 15' 42")
   135.642 (09h 02m 34s)  -1.124 ( -1d 07' 25")
  ---------------------------------------------
The error box area is 943 sq. arcmin, and its maximum
dimension is 59 arcmin (the minimum one is 19.6 arcmin).
The Sun distance was 158 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB150220_T51704/IPN/

A Swift ToO observation has been scheduled (Evans, GCN Circ. 17501).

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB150220A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17503
SUBJECT: Konus-Wind observation of GRB 150220A
DATE:    15/02/24 15:34:07 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 150220A (IPN triangulation: Hurley et al., GCN 
Circ. 17502) triggered Konus-Wind at T0=51704.661 s UT (14:21:44.661).

The burst light curve shows two emission episodes separated by ~100 s
with a total duration of ~160 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150220_T51704/

As observed by Konus-Wind, the burst
had a fluence of 3.00(-0.29,+0.37)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+13.568 s,
of 4.61(-1.05,+1.07)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+147.712 s)
is best fit in the 20 keV - 3 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.86(-0.29,+0.34)
and Ep = 211(-34,+55) keV (chi2 = 49/64 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 48/63 dof)

The spectrum near the maximum count rate
(measured from T0+8.448 to T0+16.640 s)
is best fit in the 20 keV - 3 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.98(-0.17,+0.19)
and Ep = 225(-28,+38) keV (chi2 = 54/64 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 55/63 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150220A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17504
SUBJECT: GRB 150220A: Swift-XRT observations
DATE:    15/02/24 15:39:26 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), A. Maselli 
(INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), A.P. Beardmore (U. Leicester), A. Amaral-Rogers (U.
Leicester) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 150220A, collecting 3.0 ks of Photon Counting (PC) mode data
between T0+284.9 ks and T0+300.7 ks. 

Three uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 2:
  RA (J2000):  135.3781  =  09:01:30.74
  Dec (J2000): -1.6408  =  -01:38:27.0
  Error: 6.2 arcsec (radius, 90% conf.)
  Count-rate: (6.8 +/- 1.9)e-3 ct s^-1
  Flux: (3.26 +/- 0.93)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000):  135.5356  =  09:02:8.55
  Dec (J2000): -1.6164  =  -01:36:59.1
  Error: 4.9 arcsec (radius, 90% conf.)
  Count-rate: (4.7 +/- 1.7)e-3 ct s^-1
  Flux: (2.31 +/- 0.81)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:
  RA (J2000):  135.4432  =  09:01:46.37
  Dec (J2000): -1.6372  =  -01:38:13.9
  Error: 7.1 arcsec (radius, 90% conf.)
  Count-rate: (3.3 [+1.6, -1.3])e-3 ct s^-1
  Flux: (6.5 [+3.1, -2.5])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Four catalogued sources were also detected.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020484.

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


GRB_name: GRB150220A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17505
SUBJECT: GRB 150220A: Fermi GBM observation
DATE:    15/02/24 17:40:09 GMT
FROM:    Oliver Roberts at UCD/Fermi  <oliver.roberts@ucd.ie>

O.J. Roberts (UCD) and C. Meegan (UAH) report on behalf of
the Fermi GBM Team:

"At 14:21:35.60  UT on the 20th of February 2015, the Fermi
Gamma-Ray Burst Monitor triggered and located GRB 150220A
(trigger 446134898 / 150220598), which was also detected by
IPN (Hurley  et al. 2015, GCN 17502) and Konus-Wind
(Golenetskii et al. 2015, GCN 17503 ). The GBM on-ground
location is consistent with the IPN triangulated position.

The angle from the Fermi LAT boresight is 78 degrees.

The GBM light curve shows three pulses occurring over two
main emission episodes. These episodes begin at about
T0-9.5s and T0+105s respectively. The duration (T90) of the
entire light curve is about 145s (50-300 keV).

The time-averaged spectrum of both emission episodes, from
T0-9.5s to T0+37.6s and from T0+104.7s to T0+162.6s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.02 +/- 0.03
and the cutoff energy, parameterised as Epeak, is
192.3 +/- 9.5 keV.

The event fluence (10-1000 keV) in this time interval is
(2.72 +/- 0.07)E-05 erg/cm^2. The 1.024-sec peak photon
flux measured starting from T0+17.9 s in the 10-1000 keV
band is 15.7 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well with
Epeak = 170.8 +/- 12.8 keV, alpha = -0.97 +/- 0.05
and beta = -2.41 +/- 0.21.

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


GRB_name: GRB150222A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17506
SUBJECT: GRB 150222A: Further GROND Observations
DATE:    15/02/26 14:45:45 GMT
FROM:    Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>

A. Nicuesa Guelbenzu (TLS Tautenburg), P. Wiseman, P. Schady and J. 
Greiner (all MPE Garching) report on behalf of the GROND team:

We continued to observe the field of GRB 150222A (Swift trigger 632180; 
Bernadini et al., GCN 17486) for a second night, simultaneously in 
g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at 
the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations began at 06:25:38 UT on February 24, ~34 hours after the 
GRB trigger. They were performed at an average seeing of 1.3" and at an 
average airmass of 1.1//.
In 106 min of total exposures in g'r'i'z', we detect a source in all 
optical bands towards the north-eastern edge of the the 1.7" enhanced 
Swift-XRT error circle (Beardmore et al., GCN 17494) , at a position 
consistent with that reported in Nicuesa Guelbenzu et al. (GCN 17495).
In 115 min of total NIR exposures in the JHK bands, no source is 
detected within the enhanced XRT error circle.

We detect no fading of the source between the two epochs, and therefore 
suggest that this is not the afterglow, but could be the host galaxy 
instead, unless we caught an afterglow plateau phase.


GRB_name: GRB150301A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17510
SUBJECT: GRB 150301A: Swift detection of a short burst or new SGR
DATE:    15/03/01 01:26:16 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), M. De Pasquale (INAF-IASFPA),
L. M. Z. Hagen (PSU), J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC),
A. Maselli (INAF-IASFPA), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 01:04:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a source which could be a short GRB or a new SGR (trigger=632995). 
Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 244.286, -48.697, which is 
   RA(J2000)  =  16h 17m 09s
   Dec(J2000) = -48d 41' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
structure with a duration of about 0.1 sec.  The peak count rate
was ~8500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 01:05:26.6 UT, 58.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 244.3047, -48.7131 which is equivalent to:
   RA(J2000)  = +16h 17m 13.13s
   Dec(J2000) = -48d 42' 47.2"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 73 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 113 seconds with the White filter
starting 65 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 none of
the XRT error circle. The coverage of the XRT error circle by the 8'x8' region
for the list of sources generated on-board is uncertain because the large
number of sources filled the available telemetry. The list of sources is
typically complete to about 18 mag. No correction has been made for the large,
but uncertain extinction expected. 

We note that this source is near the Galactic Plane and Bulge 
(lat = 1.36, lon = 334) and so this might be a previously-unknown
Soft Gamma Repeater. The burst has significant emission above 100 keV,
which is unusual, but not unprecedented, for an SGR.  Further analysis
of the full data set and continued observation is required to
determine the nature of this source. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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: GRB150301A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17511
SUBJECT: GRB 150301A: Fermi GBM observation
DATE:    15/03/01 05:25:53 GMT
FROM:    Valerie Connaughton at UAH/NSSTC  <valerie.connaughton@nasa.gov>

Valerie Connaughton and Peter Jenke (UAH) and Adam Goldstein (NASA MSFC)
report on behalf of the Fermi GBM Team:

"At 01:04:28.65 UT on 01 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150301A (trigger 446864671 / 150301045)
which was also detected by the Swift/BAT (Lien et al. 2015, GCN 17510).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 105 degrees.

The GBM light curve consists of a single peak about 50 ms in duration.
The counts registered in the NaI detectors are strongly peaked in the
50 - 300 keV energy range typical for GRBs.  From the quicklook
data, the softness ratio for the event (20 - 100 keV / 100 - 500 keV)
is 0.4 +/- 0.3, typical for fairly hard GRBs.  By contrast,
the corresponding softness ratios for recent triggers from
SGR 1935+2154 and AXP 4U 0142+61 were
4.4 +/- 1.8, 3.4 +/- 1.0, and 2.2 +/- 0.4.

The time-averaged spectrum from T0-0.016 s to T0+0.032 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.53 +/- 0.35 and
the cutoff energy, parameterized as Epeak, is 185 +/- 49 keV.

The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-07 erg/cm^2. The 16-msec peak photon flux measured
starting from T0-0.016 s in the 10-1000 keV band
is 29 +/- 4 ph/s/cm^2.

The spectral characteristics of this burst are more like a GRB than
an SGR.  We think it is therefore unlikely that this event is a burst
from a new SGR and conclude that it is, instead, a short GRB.


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


GRB_name: GRB150301A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17513
SUBJECT: GRB 150301A: GROND Observations
DATE:    15/03/01 14:29:55 GMT
FROM:    Corentin Delvaux at MPE  <delvaux@mpe.mpg.de>

M. Tanga, C. Delvaux, J. Greiner (all MPE Garching) and D. A. Kann (TLS
Tautenburg) report on behalf of the GROND team:

We observed the field of GRB 150301A (Swift trigger 632995; Lien et al.,
GCN #17510) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 06:02 UT on 01-03-2015, 4.97 hrs after the GRB
trigger. They were performed at an average seeing of 1.4" and at an
average airmass of 1.5.

We found two point sources within the 5.0" Swift-XRT error circle reported
by Lien et al. (GCN #17510). The first source is at

RA (J2000) = 16 h 17 m 13.08 s
DEC (J2000) = -48d 42' 45.7"

The second source is at

RA (J2000) = 16 h 17 m 13.34 s
DEC (J2000) = -48d 42' 49.7"

with an uncertainty of 0.3" in each coordinate for both sources.

Based on the first 50 min of total exposures in g'r'i'z' and 40 min in
JHK, we estimate the following preliminary magnitudes (all in AB system):

For the first source:

g' > 24.4 mag,
r' > 24.5 mag,
i' = 22.0 +/- 0.1 mag,
z' = 21.0 +/- 0.3 mag,
J = 18.8 +/- 0.2 mag,
H = 18.3 +/- 0.2 mag, and
K > 18.3 mag.

For the second source:

g' > 24.4 mag,
r' > 24.5 mag,
i' = 23.1 +/- 0.1 mag,
z' = 22.2 +/- 0.1 mag,
J = 19.6 +/- 0.3 mag,
H = 19.1 +/- 0.4 mag, and
K > 18.3 mag.

Both objects appear to be constant over the duration of our observation.
Therefore we suppose they are not related to the burst.

We note the field is crowded. We also notice the presence of a bright star
(~14 mag) west of the Swift-XRT error circle covering around 10% of the
encircled region.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=3.31 mag in the
direction of the burst (Schlafly & Finkbeiner 2011).


GRB_name: GRB150301B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17515
SUBJECT: GRB 150301B: Swift detection of a burst with an optical afterglow
DATE:    15/03/01 19:50:01 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), M. De Pasquale (INAF-IASFPA),
A. Maselli (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 19:38:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150301B (trigger=633180).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 89.157, -57.977 which is 
   RA(J2000) = 05h 56m 38s
   Dec(J2000) = -57d 58' 37"
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 20 sec.  The peak count rate
was ~4000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 19:39:26.4 UT, 82.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 89.16636, -57.97051 which is equivalent
to:
   RA(J2000)  = 05h 56m 39.93s
   Dec(J2000) = -57d 58' 13.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 29 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 consistent with the Galactic value of 6.16
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 85 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 05:56:39.86 =  89.16608
  DEC(J2000) = -57:58:10.4  = -57.96956
with a 90%-confidence error radius of about 0.61 arc sec. This position is 31.9
arc sec. from the center of the BAT error circle. The estimated magnitude is
16.22 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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: GRB150301C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17516
SUBJECT: GRB 150301C : (Swift trigger 633105) Swift observations
DATE:    15/03/01 20:31:02 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), J. Tueller (GSFC), T. N. Ukwatta (LANL),
F. Marshall (NASA/GSFC), D. Malesani (DARK/NBI), L. Hagen (PSU),
M. de Pasquale (INAF-IASFPA), A. Maselli (INAF-IASFPA), D.N. Burrows (PSU),
K. Page (U. Leicester), N. P. M. Kuin (UCL-MSSL)

  
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of possible GRB 150301C (trigger #633105)
(Lien, et al., GCN Circ. 17512).  The BAT ground-calculated position is
RA, Dec = 11.319, 41.861 deg which is
    RA(J2000)  =  00h 45m 16.6s
    Dec(J2000) = +41d 51' 40.0"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The significance in the BAT image was 10.1, so we are sure that this was
a real astrophysical source.  The partial coding was 69%.

The location is well within the visible light of M31.  A more distant galaxy,
[JSD2012] 170, which has a size of 0.11 arcmin, is within the BAT error
circle.  In 1.9 ks of data, the Swift XRT found only a single very weak source
(2.8 sigma), consistent with the position of a known source within the BAT
error circle, [PFH2005] 622, with a count rate of (5.3+/-1.9) x 10^-03 c/s.  We
cannot state whether there is any variability of this source at this time.  The
XRT position of this source is:

RA (J2000)  00h 45m 14.4s
Dec (J2000) +41d 50' 37.7"

The BAT mask-weighted light curve shows a single weak FRED peak.  T90 (15-350 keV)
is 14 +- 3 sec (estimated error including systematics).
  
The time-averaged BAT spectrum from T-0.6 to T+15.0 sec is best fit by a power-
law model with an exponential cutoff.  The power law index of the time-averaged
spectrum is poorly defined but is nominally -0.8 +- 2.  The peak energy is
38 +- 7 keV.  The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+1.32 sec in the 15-150 keV band is
0.6 +- 0.2 ph/cm2/sec.  A simple power-law fit has a photon index of 1.96 +- 0.25.
All the quoted errors are at the 90% confidence level.

If this source was in M31, its isotropic energy output was 1.5 x 10^43 ergs
in 15.6 seconds in the range 15-150 keV.

It is very possible, given the softness of the source, that this is a non-GRB
in M31.  The color:duration is within the distribution of long GRBs.  No XRT
source was seen in the initial observations, whereas we might expect most
sources in M31 bright enough to be seen in BAT would be very bright in XRT.
Therefore the source is likely to be highly absorbed.  The results of the
batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/633105/BA/

The Swift/UVOT began settled observations of the field 102 s after
the BAT trigger (Lien et al., GCN Circ. 17512). No new source within
the BAT error circle 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
exposures are:

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

white              102         4151          369        >20.39
v                  592         4562          216        >18.55
b                  518         5241           96        >19.08
u                  261         5177          461        >19.69
uvw1               641         4973          216        >19.27
uvm2               617         4768          216        >19.20
uvw2               568         4357          216        >19.41

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).

Further Swift observations are planned.

[GCN OPS NOTE(01mar15): Per author's request, the affiliation was corrected for KP.]


GRB_name: GRB150301A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17517
SUBJECT: GRB 150301A: Swift-XRT refined Analysis
DATE:    15/03/01 20:45:59 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M. de Pasquale (INAF-IASFPA), A. Maselli  (INAF-IASFPA), J.A. Kennea
(PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U.
Leicester), A. Amaral-Rogers (U. Leicester), J.P. Osborne (U.
Leicester), A. Melandri (INAF-OAB) and A.Y. Lien report on behalf of
the Swift-XRT team:

We have analysed 147 s of XRT data for GRB 150301A (Lien et al. GCN
Circ. 17510), from 50 s to 43.7 ks after the  BAT trigger. The data are
entirely in Windowed Timing (WT) mode (the first 6 s were taken while
Swift was slewing). 

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.53 (+0.18, -0.59), followed by a break at T+112 s to
an alpha of 2.6 (+0.6, -0.7).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.71 (+0.21, -0.20). The
best-fitting absorption column is  5.6 (+/-0.7) x 10^22 cm^-2, in
excess of the Galactic value of 1.3 x 10^22 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 9.1 x 10^-11 (2.0 x 10^-10) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      5.6 (+/-0.7) x 10^22 cm^-2
Galactic foreground: 1.3 x 10^22 cm^-2
Excess significance: 10.5 sigma
Photon index:      1.71 (+0.21, -0.20)

If the light curve continues to decay with a power-law decay index of
2.6, the count rate at T+24 hours will be 9.7 x 10^-7 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.8 x
10^-17 (1.9 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/00632995.

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


GRB_name: GRB150301B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17518
SUBJECT: GRB 150301B: MASTER early  OT detection 
DATE:    15/03/01 20:51:41 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

E. Gorbovskoy, V. Lipunov,  V.Kornilov,
N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D.Kuvshinov,
Lomonosov Moscow State University,
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.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, 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 SAAO was pointed to the  GRB150301.82 (Lien et al, GCN 17515) 
60 sec after notice time 
and 79 sec after trigger time at 2015-03-01 19:39:23 UT in two 
polarizations. On our first (10s 
exposure)  set we  found 1 optical transient within SWIFT error-box (ra=05 
56 37 dec=-57 58 35 r=0.050000).

                      T_start      RA            DEC     Exp     unfiltered
                          s                                      magnitude
  2015-03-01 19:39:23   79.0   05h 56m 39.94s  -57d 58m  10.0s     15.3

The error is about 0.5 arcsec. This position is coincidet with UVOT data.
We detected OT before maximum brightness.
The 5-sigma upper limit has been about 16.8 mag . The telegram is 
generated automatically.
We have number of the images after maximum in two polarizations. The 
reduction is continuated.
The message may be cited.


GRB_name: GRB150301A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17519
SUBJECT: GRB 150301A: Swift-BAT refined analysis
DATE:    15/03/01 22:13:47 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), 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 (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-210 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150301A (trigger #632995)
(Lien, et al., GCN Circ. 17510).  The BAT ground-calculated position is
RA, Dec = 244.281, -48.732 deg which is
  RA(J2000)  =  16h 17m 07.5s
  Dec(J2000) = -48d 43' 56.2"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.

The mask-weighted light curve shows a single short FRED peak that starts at
~ T0 and ends at ~ T+0.5 s. T90 (15-350 keV) is 0.48 +- 0.14 sec (estimated error
including systematics).

The time-averaged spectrum from T+0.00 to T+0.56 sec fit by a simple power-law
model has a power law index of 1.44 +- 0.23 (chi squared 54.10 for 57 d.o.f.).
The fluence in the 15-150 keV band is 7.4 +- 1.0 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.22 sec in the 15-150 keV band
is 1.0 +- 0.2 ph/cm2/sec.

A single blackbody fit to the time-averaged spectrum shows a blackbody
temperature of 15.11 +- 2.92 keV (chi squared 74.66 for 57 d.o.f.).
A thermal bremsstrahlung model fit shows the temperature of 199.36 keV
(chi squared 55.72 for 57 d.o.f.).

Despite being near the Galactic Plane and Bulge (lat = 1.36, lon = 334), both the
fast-decaying XRT light curve and Fermi/GBM observation (Connaughton et al.,
GCN Circ. 17511) suggests that this source is more likely to be a short GRB than
a SGR. In addition, there are no other BAT detections of this source before or since
this trigger.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/632995/BA/


GRB_name: GRB150301B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17520
SUBJECT: GRB 150301B: Enhanced Swift-XRT position
DATE:    15/03/01 22:44:01 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 386 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150301B, 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 = 89.16660, -57.96950 which is equivalent
to:

RA (J2000): 05h 56m 39.98s
Dec (J2000): -57d 58' 10.2"

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: GRB150301A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17521
SUBJECT: GRB 150301A: Swift/UVOT Upper Limits
DATE:    15/03/02 00:59:47 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150301A
66 s after the BAT trigger (Lien et al., GCN Circ. 17510).
No optical afterglow consistent with the XRT position (Lien et al.
GCN Circ. 17510) or GROND candidates (Tanga et al. GCN Circ. 17513)
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
exposures are:

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

white               66         4931          306        >21.08
v                 5143         5343          196        >19.40
b                 4526        10879          750        >21.16
u                 4321         5926          362        >20.08
uvw1              5553         5752          196        >19.61
uvm2              5347         5547          196        >19.40
uvw2              4937         5137          196        >19.82

The magnitudes in the table are not corrected for the substantial Galactic
extinction due to the reddening of E(B-V) = 3.84 in the direction of the
burst (Schlegel et al. 1998).  We note that the photometry is likely
affected by a nearby bright foreground star.


GRB_name: GRB150301B
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17522
SUBJECT: GRB 150301B: GROND afterglow observations
DATE:    15/03/02 01:55:37 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann (TLS Tautenburg), C. Delvaux and J. Greiner (both MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 150301B (Swift trigger 633180; Lien et al.,
GCN #17515) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 00:09 UT on 2015-03-02, 4.5 hrs after the GRB
trigger. They were performed at an average seeing of 1".0 and at an
average airmass of 1.1.

We detect the optical afterglow candidate reported by Lien et al. (GCN
#17515) and Buckley et al. (GCN #17518).

Based on 7.7 min of total exposure time in g'r'i'z' and 8.0 min in JHK, 
centered 5 hrs after the GRB, we estimate the following preliminary
magnitudes (all in AB system):

g' = 21.7 +/- 0.2 mag,
r' = 21.4 +/- 0.1 mag,
i' = 21.2 +/- 0.1 mag,
z' = 21.0 +/- 0.1 mag,
J = 20.5 +/- 0.3 mag,
H = 20.6 +/- 0.4 mag, and
K > 17.9 mag.

Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as
well as 2MASS field stars and are not corrected for the expected Galactic 
foreground extinction corresponding to a reddening of E_(B-V)=0.08 mag in
the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB150301B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17523
SUBJECT: GRB 150301B: X-shooter spectroscopy
DATE:    15/03/02 02:07:10 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T. Kruehler (ESO), 
H. Flores (GEPI/Obs. de Paris), and J.P.U. Fynbo (DARK/NBI) 
report on behalf of a larger collaboration:

We observed the afterglow of GRB 150301B (Lien et al. GCN 17515, 
Buckley et al. GCN 17518, Kann et al. GCN 17522) with X-shooter at the 
Very Large Telescope (Paranal Observatory, Chile). Observations started 
at 00:45 UT (5.12 hr after the burst), and consisted of 6x600 s exposures 
covering the spectral range between 3 000 and 18 000 Angstroms.

In the acquisition image the afterglow is detected with R(Vega) = 21.0 mag, 
as compared to stars of the USNOB-1.0 catalogue.

On a preliminary reduction we detect a weak continuum with absorption 
features of FeII, MgII and MgI at a common redshift of z = 1.5169, which 
we suggest as the redshift of the GRB.

We acknowledge the excellent support provided by Paranal staff, and in 
particular Andrea Mehner, Tayyaba Zafar, and Marcelo Lopez.


GRB_name: GRB150301B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17524
SUBJECT: GRB 150301B: Swift-BAT refined analysis
DATE:    15/03/02 05:24:04 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), 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 (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
(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 150301B (trigger #633180)
(Lien, et al., GCN Circ. 17515).  The BAT ground-calculated position is
RA, Dec = 89.159, -57.969 deg which is
  RA(J2000)  =  05h 56m 38.3s
  Dec(J2000) = -57d 58' 07.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.

The mask-weighted light curve shows a single-peaked structure that starts at ~ T0,
peaks at ~ T+3 s, and ends at ~ T+16 s. T90 (15-350 keV) is 12.44 +- 1.49 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.34 to T+15.62 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.46 +- 0.07.  The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+3.65 sec in the 15-150 keV band
is 3.0 +- 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/633180/BA/


GRB_name: GRB150301B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17525
SUBJECT: GRB 150301B: Fermi GBM detection
DATE:    15/03/02 05:26:50 GMT
FROM:    Eric Burns at U of Alabama  <eb0016@uah.edu>

E. Burns (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 19:38:04.51 UT on 01 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150301B (trigger 446931487/150301818)
which was also detected by the Swift/BAT (Lien et al. 2015, GCN 17515).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 39 degrees.

The GBM light curve consists of one main peak
with a duration (T90) of about 13 s (50-300 keV).
The time-averaged spectrum from T0-2.560 s to T0+13.824 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 256 +/- 32 keV.
A Band function fits the spectrum equally well with
Epeak= 180 +/- 38 keV, alpha = -1.1 +/- 0.1 and beta = -2.0 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(4.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.560 s in the 10-1000 keV band
is 4.5 +/- 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: GRB150302A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17526
SUBJECT: GRB 150302A: Swift detection of a burst
DATE:    15/03/02 05:56:18 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), M. M. Chester (PSU),
M. De Pasquale (INAF-IASFPA), A. Maselli (INAF-IASFPA),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 05:42:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150302A (trigger=633237).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 175.508, +36.827 which is 
   RA(J2000) = 11h 42m 02s
   Dec(J2000) = +36d 49' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single complex peak
structure with a duration of about 30 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 05:44:17.5 UT, 100.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 175.5314, 36.8110 which is equivalent to:
   RA(J2000)  = +11h 42m 7.54s
   Dec(J2000) = +36d 48' 39.6"
with an uncertainty of 5.9 arcseconds (radius, 90% containment). This
location is 88 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 2 seconds with the White filter 
starting 109 seconds after the BAT trigger. No credible afterglow
candidate has  been found in the initial data products. Results from
the 2.7'x2.7' sub-image are not available at this time. 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 A. Y. Lien (amy.y.lien 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: GRB150302A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17527
SUBJECT: GRB 150302A: NOT afterglow candidate
DATE:    15/03/02 06:25:52 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

J.P.U. Fynbo (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI),
T. Kruehler (ESO), and M. Saajasto (NOT) report on behalf of a larger collaboration:

We observed the field of GRB 150302A (Lien et al., GCN 17526) using the 
2.5m Nordic Optical Telescope with AlFOSC. Observations starting at 
05:59 UT (17 min after the GRB) reveal an optical counterpart within the 
XRT error box at coordinates 11:42:07.43 +36:48:38.9 (J2000), with a 
magnitude of r=22.3, calibrated against SDSS field stars.

[GCN OPS NOTE(02mar15), Per author's request, MS was added to the author list.]


GRB_name: GRB150302A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17528
SUBJECT: GRB 150302A: UVOT Observations
DATE:    15/03/02 07:08:01 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT group:

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 3435 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 0.02


GRB_name: GRB150302A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17529
SUBJECT: GRB 150302A: KAIT Optical Upper Limit
DATE:    15/03/02 07:30:14 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150302A (Lien et al.,
GCN 17526) starting at 05:44:50 UT, 134 s after the burst, under
bright moon condition. First few images were useless until ~18
minutes after the burst. Observations were performed with an
automatic sequence in the clear (roughly R), V, and I filters,
and the exposure time was 20 s per image. We do not detect the
afterglow candidate (Fynbo et al., GCN 17527) in our images,
with a limiting magnitude of R~17.8 (calibrated to USNO B1.0)
at a mid-time of 18.9 minutes after the burst.


GRB_name: GRB150301B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17530
SUBJECT: GRB 150301B: LCOGT-Sutherland observations
DATE:    15/03/02 09:00:17 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), J. Japelj, A. Gomboc (U. Ljubljana),
C.G. Mundell (U. Bath), on behalf of a large collaboration report:

One of the Las Cumbres Observatory 1-m telescopes in Sutherland
(South Africa) began observing Swift and Fermi GRB 150301B
(Lien et al. GCN 17515; Burns et al. GCN 17525) on March 01
at 20:07:30 UT, i.e. ~29.4 minutes after the BAT trigger
with the r', i', and g' filters.

We detect the optical afterglow (Lien et al. GCN 17515;
Buckley et al. GCN 7518; Kann et al. GCN 17522; de Ugarte
Postigo et al. GCN 17523) with the following magnitudes:

Mid time from  Total Exp   Filter    Magnitude
trigger (min)   (s)
-------------------------------------------------
37.7            360         r'     18.85 +- 0.25
42.3            360         i'     18.5  +- 0.3
-------------------------------------------------

Values have been calibrated against nearby USNOB-1 stars
(R2 and I). Compared with earlier (Buckley et el.)
and later (Kann et al.) observations, our values
suggest an overall power-law decay index ~1.


GRB_name: GRB150301B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17531
SUBJECT: GRB 150301B:  Swift/UVOT Observations
DATE:    15/03/02 14:28:45 GMT
FROM:    Margaret Chester at PSU  <chester@swift.psu.edu>

M. M. Chester (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150301B
86 s after the BAT trigger (Lien et al., GCN Circ. 17515).  A fading 
source consistent with the XRT position (Evans et al. GCN Circ. 17520) 
and the optical transient reported by Buckley et al. (GCN Circ. 17518)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  05:56:39.89 =  89.16622 (deg.)
   Dec (J2000) = -57:58:10.4  = -57.96955 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits for the White finding 
chart and subsequent exposures 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            86          236          147         16.2 +/- 0.1
white             3986         4121          133        >20.2
v                 5833         6033          197        >19.7
b                 3782         3982          197        >19.6
u                  298          543          241         17.1 +/- 0.1
w1                6243        10068          579        >19.9
m2                6038         6237          197        >19.8
w2                5628        16054          963        >21.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.08 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB150220A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17532
SUBJECT: GRB 150220A: further Swift-XRT observations
DATE:    15/03/02 16:17:48 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri (INAF/OAB) reports on behalf of the Swift-XRT team:


Swift-XRT observed again the field of the IPN GRB 150220A (Hurley et al. GCN 17502; Roberts & Meegan GCN 17505). The observation started on 2015-02-27 at 14:41 UT, i.e. ~7 days after the burst detection.

For the three sources detected by Swift-XRT, reported in D'Elia et al. (GCN 17504) we did not find any evidence for fading. In particular:

Source 2:
  Epoch1: (6.8 +/- 1.9)e-3 ct s^-1
  Epoch2: <5.4e-3 ct s^-1 (3sigma upper limit)

Source 3:
  Epoch1: (4.7 +/- 1.7)e-3 ct s^-1
  Epoch2: <4.1e-3 ct s^-1 (3sigma upper limit)

Source 7:
  Epoch1: (3.3 +/- 1.7)e-3 ct s^-1
  Epoch2: <3.0e-3 ct s^-1 (3sigma upper limit)

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


GRB_name: GRB150301B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17533
SUBJECT: GRB 150301B: Swift-XRT refined Analysis
DATE:    15/03/02 19:50:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Maselli  (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), J.A. Kennea (PSU), A. Amaral-Rogers (U. Leicester), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT
team:

We have analysed 5.7 ks of XRT data for GRB 150301B (Lien et al. GCN
Circ. 17515), from 67 s to 69.5 ks after the  BAT trigger. The data
comprise 67 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. 17520).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.11 (+0.05, -0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.81 (+0.18, -0.10). The
best-fitting absorption column is  consistent with the Galactic value
of 6.2 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.7 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 6.2 x 10^20 cm^-2
Intrinsic column:    6 (+/-14) x 10^20 cm^-2 at z=1.5169
Photon index:      1.81 (+0.18, -0.10)

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 3.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-13 (1.4 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/00633180.

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


GRB_name: GRB150302A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17534
SUBJECT: GRB 150302A: Enhanced Swift-XRT position
DATE:    15/03/02 20:22:36 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 637 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150302A, 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 = 175.53116, +36.81107 which is equivalent
to:

RA (J2000): 11h 42m 7.48s
Dec (J2000): +36d 48' 39.8"

with an uncertainty of 3.3 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: GRB150302A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17535
SUBJECT: GRB 150302A: Swift-XRT refined Analysis
DATE:    15/03/02 20:56:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.
Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia
(ASDC) and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 11 ks of XRT data for GRB 150302A (Lien et al. GCN
Circ. 17526), from 92 s to 28.9 ks after the  BAT trigger. The data
comprise 5 s in Windowed Timing (WT) mode (the first 7 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 Goad et al.
(GCN Circ. 17534).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.91 (+0.07, -0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+0.8, -0.6). The
best-fitting absorption column is  1.9 (+2.1, -1.6) x 10^21 cm^-2, in
excess of the Galactic value of 1.8 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.1 x 10^-11 (4.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.9 (+2.1, -1.6) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index:      2.3 (+0.8, -0.6)

If the light curve continues to decay with a power-law decay index of
1.91, the count rate at T+24 hours will be 1.0 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.2 x
10^-15 (4.9 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00633237.

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


GRB_name: GRB150301C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17536
SUBJECT: GRB 150301C: XRT detection of a potential counterpart of BAT trigger 633105
DATE:    15/03/02 23:19:36 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

Phil Evans (U. Leicester) , Alessandro Maselli (INAF-IASFPA), David Burrows (PSU), 
Sergio Campana (INAF-OAB), Neil Gehrels (GSFC), Jamie Kennea (PSU), 
Amy Lien (GSFC/UMBC), Lea Hagen (PSU), Daniele Malesani (DARK/NBI), 
Frank Marshall (GSFC), Julian Osborne (U. Leicester), Kim L. Page (U Leicester), 
Massimiliano De Pasquale (INAF-IASFPA) report on behalf of the Swift team:

We report further XRT observations of the highly unusual transient or GRB detected 
by BAT on March 1 ( trigger 633105 or GRB150301C; Lien et al., GCN Circ 17512; 
Stamatikos et al., GCN Circ 17516).  It lasted about 20 seconds in BAT and has a 
location in M31, but had very weak X-ray emission. The XRT found a single source 
within the BAT error circle, which is coincident with the known X-ray source [PFH2005] 622. 
This source was previously reported in an XMM-Newton survey of M31 (Pietsch et al., 
A&A, 434, 483, 2005), and was classified as a "hard" source based on the hardness ratio (see 
definition in Pietsch et al. 2005). The paper suggests that these "hard" sources  may be
X-ray binaries, Crab-like SNRs, or AGNs.

Using the faint-source-optimised detection system from the 1SXPS catalogue (Evans et al., 
ApJS 210, 8, 2014), the XRT source is detected with a likelihood of 18.3 in the first observation 
of the BAT error region. This corresponds to a "Good"-flagged object, i.e. a >3-sigma detection.

The refined XRT position is RA,Dec = 11.3107, +41.8431 degrees which corresponds to

RA (J2000):   00h 45m 14.57s
Dec (J2000): +41d 50' 35.1"

with an uncertainty of 5.7 arcsec (radius, 90% confidence). This is 4 arcsec from the catalogued 
position of [PFH2005] 622, which is at RA=00h 45m 14.87,Dec=+41d 50' 33'' with an uncertainty 
of 1.5 arcsec. Hence, the XRT position is consistent with the position of [PFH2005] 622.

During the first XRT observation, starting at T0+105s and lasting 1.9 ks, the source is detected with 
a count-rate of 6.0 (+2.3, -1.8) x10^-3 ct/sec. In the subsequent observations, from T0+44.9 ks and 
totalling 6ks exposure, the source is undetected, with an upper limit of 1.2 x10^-3 ct/sec, consistent 
with fading.

Swift-XRT has previously observed this location for a total of ~4ks, corresponding to "Stacked image 
7598" in the 1SXPS catalogue. The source was not detected in this dataset, with an upper limit of 
2.2x10^-3 ct/sec, significantly below the level at which we have detected it in this observation. 
Additionally, XMM-Newton observations (Pietsch et al., 2005) detected this X-ray source in 2005 
with a flux of 6.9x10^-15 erg/cm^2/s. The peak rate in our observations corresponds to 
~2x10^-13 erg/cm^2/s, i.e. ~35 times brighter than the XMM detection. At the distance of M31, 
these fluxes correspond to a luminosity of ~5x10^35 erg/s (0.2-4.5 keV) in the XMM-Newton observations, 
and ~1.4x10^37 erg/s (0.3-10 keV) in the XRT observations. For comparison, the average luminosity 
in BAT at this distance was 1.25x10^42 erg/s in 15-150 keV (Stamatikos et al., GCN Circ 17516).

We therefore conclude that XRT has detected a bursting source that is likely the counterpart to 
BAT trigger 633105.


GRB_name: GRB150302A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17537
SUBJECT: GRB 150302A: MITSuME Okayama upper limits
DATE:    15/03/02 23:43:49 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 150302A (Lien et al., GCNC 17526)
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 2015-03-02 11:23:12 UT (~5.7 h after the burst).
We could not detect the previously reported afterglow (Fynbo et al., GCNC 17527)
in all the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.27847    12:23:36    5880.0   >19.7  >19.8  >19.2
0.36250    14:24:37    6240.0   >20.2  >20.2  >19.5
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB150302A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17538
SUBJECT: GRB 150302A: Swift/UVOT Upper Limits 
DATE:    15/03/02 23:45:02 GMT
FROM:    Margaret Chester at PSU  <chester@swift.psu.edu>

M. M. Chester (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150302A
110 s after the BAT trigger (Lien et al., GCN Circ. 17526). No optical 
afterglow consistent with the optical candidate reported by Fynbo et al. 
(GCN Circ. 17527) 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) are as follows.  We report only the 
second finding chart (FC) exposure and subsequent exposures; the first 
finding chart exposure was too short (< 2 s) to be useful.

Filter         T_start(s)   T_stop(s)      Exp(s)        UL (3-sigma)

white_FC        3436         3585          147         >21.4
white           3436        11616          993         >22.1
v               5262        28248         1077         >21.0
b               3799        17368         1738         >22.2
u               3594        23030         2557         >21.9
w1              5672        22421         1960         >21.5
m2              5466        28871         1690         >22.4
w2              4210        27342          995         >21.4

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: GRB150302A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17539
SUBJECT: GRB 150302A, Swift-BAT refined analysis
DATE:    15/03/03 04:01:52 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

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 (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-61 to T+242 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 150302A (trigger #633237)
(Lien, et al., GCN Circ. 17526).  The BAT ground-calculated position is
RA, Dec = 175.515, 36.852 deg which is
 RA(J2000)  =  11h 42m 03.6s
 Dec(J2000) = +36d 51' 06.3"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a weak single-peaked structure that
starts
at ~ T-1 s, peaks at ~T+3 s, and ends at ~T+20 s. T90 (15-350 keV) is 23.74
+- 8.79 sec
(estimated error including systematics).

The time-averaged spectrum from T-1.14 to T+28.23 sec is best fit by a
simple
power-law model.  The power law index of the time-averaged spectrum is
1.69 +- 0.33.  The fluence in the 15-150 keV band is 2.6 +- 0.6 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+2.61 sec in the 15-150 keV band
is 0.4 +- 0.1 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/633237/BA/


GRB_name: GRB150302A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17540
SUBJECT: GRB 150302A: Mondy optical upper limit
DATE:    15/03/03 18:09:34 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev 
(ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB 150302A (Lien et al., GCN 17526) with 
AZT-33IK telescope of Sayan observatory (Mondy). We obtained several 
images in R-filter on Mar., 02, starting (UT) 15:55:19. Within enhanced 
XRT error circle (Goad et al., GCN 17534)  we do not detect any optical 
source. In particular, we do not detect the afterglow candidate (Fynbo 
et al., GCN 17527). Upper limit is following

Date       UT start   t-T0     Filter   Exp.  UL(3sigma)
                       (mid, days)       (s)

2015-03-02 15:55:19   0.44045  R       43*60  21.6


The photometry   is based on nearby SDSS DR9 stars
SDSS9_id         R(Lupton) 
J114204.20+364911.9 16.90 
J114201.34+365107.3 19.45 
J114159.81+365111.7 19.15 


GRB_name: GRB150301C
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17541
SUBJECT: Trigger 633105 (aka GRB150301C): Swift/UVOT Observations of XRT Counterpart
DATE:    15/03/04 03:16:06 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:


A point source is detected by UVOT that is consistent with the XRT
counterpart and 2.5 arcsec from the XMM-Newton source discussed in
Evans et al. (GCN Circ. 17536).  This source is also seen in archival
DSS imaging.  It is unclear if this is the same object detected by XRT
or a serendipitous source.  Given how crowded the field is, it is also
likely that the UVOT source is comprised of multiple individual sources.
The coordinates of the UVOT source are
   RA(J2000) = 00:45:14.76 = 11.31150
   DEC(J2000) = +41:50:35.2 = 41.84311

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

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

white              102         4151          369         19.22+-0.13
v                  592         4562          216        >18.53
b                  518         5241           96        >19.08
u                  261         5177          461         18.60+-0.15
uvw1               641        79666         5117         18.64+-0.05
uvm2               617        45953         1237         18.94+-0.13
uvw2               568         4357          216         18.99+-0.27

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.06 in the direction
of the source (Schlegel et al. 1998).

This field has also been observed previously by UVOT as part of a
different observing campaign, primarily in 2013 and 2014. The
stacked images have the following detections:

Filter      Exp(s)        Mag

v            1406     19.04+-0.19
b            1445     19.77+-0.15
u           27521     18.65+-0.03
uvw1        52236     18.57+-0.02
uvm2        58908     18.65+-0.03
uvw2        65719     18.61+-0.02

These indicate possible variability of the source, but further
analysis will be required to confirm this.


GRB_name: GRB150302A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17542
SUBJECT: GRB 150302A: BOOTES-2/TELMA upper limit
DATE:    15/03/04 20:38:30 GMT
FROM:    Soomin Jeong at IAA-CSIC  <sjeong@iaa.es>

S. Jeong (IAA-CSIC & SKKU), M. Jelinek, J. C. Tello (IAA-CSIC) and A. J.
Castro-Tirado (IAA-CSIC & ISA-UMA), on behalf of a larger
collaboration, report:

"The 60 cm BOOTES-2/TELMA robotic telescope (Malaga, Spain) automatically
responded to the Swift trigger of GRB 150302A (Lien et al., GCN 17526).
The first exposure started at 05:43:54 UT (78s after the trigger) and a
sequence of 79 images was obtained (3s each, z filter). A median combined
image revealed no credible optical source detection neither at the
enhanced XRT error circle (Goad et al., GCN 17534) nor at the optical
counterpart position (Fynbo et al., GCN 17527) down to 18.5 mag (3 sigma
UL).
It is calibrated against the SDSS z-field."


GRB_name: GRB150301C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17543
SUBJECT: BAT trigger 633105 (GRB 150301C): NOT r-band upper limit
DATE:    15/03/04 22:05:01 GMT
FROM:    Zach Cano at U of Iceland  <zewcano@gmail.com>

Z. Cano (Univ. Iceland), D. Malesani, J. P. U. Fynbo (DARK/NBI),
A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), N. R. Tanvir (Univ.
Leicester),
P. Jakobsson (Univ. Iceland), M. Saajasto, T. Pursimo (NOT), report on
behalf of a larger collaboration:

We observed the field of BAT trigger 633105 (Lien et al., GCN Circ. 17512)
with the
2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC on 01-Mar-2015 and
03-Mar-2015, obtaining 6x300 s of SDSS r-band exposures in each epoch.  The
mid
exposure times of our observations correspond to +0.60 and +2.59 days from
the
initial trigger, respectively.

Consistent with the X-ray position of the known source [PFH2005] 622
(thought to
be associated with the gamma-ray transient; Evans et al., GCN Circ. 17536),
we
detect one object at coordinates:

RA = 00:45:14.80
Dec = +41:50:32.35

Its magnitude is R =  22.7 +- 0.1 (using a USNO-A2.0 star in the field for
calibration). Two more objects are also detected in close proximity of the
XMM
position (Pietsch et al. 2005, A&A, 434, 483), and potentially consistent
with
it, including the source seen by UVOT by Hagen & Lien (GCN 17541), which
appears
to be quite blue (it has R = 22.3 +- 0.1 in our image).

We carried out digital image subtraction between our two images, where we
subtracted the first epoch from the second by using an adaptation of the
ISIS
software. In our difference image we do not detect any residual flux at the
combined XRT and XMM location, down to an upper limit of R > 23.2.

All objects seen in the NOT image are also apparent in the deep, archival
data
from the PAndAS survey (McConnachie et al. 2009, Nature, 461, 66), which
also reveals
a few more, fainter objects in the close proximity of the XMM position. No
object seems
to have varied significantly.

A gif animation of the two epochs of NOT imaging, and the difference image,
can
be retrieved from:
http://www.astro.ku.dk/~malesani/GRB/150301C/subtraction.gif

A comparison image of the NOT image from 01-Mar-2015 and the PAndAS image
can be found at:
http://www.astro.ku.dk/~malesani/GRB/150301C/comparison_NOT_PAndAS.png


GRB_name: GRB150301C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17544
SUBJECT: Further X-ray observations of  Swift J0045.2+4151 (aka Sw J0045 aka GRB 150301C aka [PFH2005] 622)
DATE:    15/03/04 23:07:43 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

Alessandro Maselli (INAF-IASFPA), Phil Evans (U. Leicester),
David Burrows (PSU), Sergio Campana (INAF-OAB),
Neil Gehrels (GSFC), Jamie Kennea (PSU), Amy Lien (GSFC/UMBC),
Daniele Malesani (DARK/NBI), Craig. B. Markwardt (GSFC),
Frank Marshall (GSFC), Julian Osborne (U. Leicester),
David. M. Palmer (LANL), Kim L. Page (U Leicester),
Rhaana L. C. Starling (U Leicester)
report on behalf of the Swift team:

Swift continues to observe the field of BAT trigger 633105
(aka GRB 150301C) with sky location in M31. To avoid further
naming confusion, this object will be referred as Swift J0045.2+4151
hereafter. The XRT continues to detect only a single source within
the BAT error circle at a position coincident with the previously
known XMM-Newton source, [PFH2005] 622 (Pietsch et al. 2005).
For the rest of this circular we assume that the X-rays detected by
XRT are from [PFH2005] 622.

The XRT has acquired four observations so far. The source
(which we presume is [PFH2005] 622) was detected in the first snapshot,
(T0+107s to T0+720s), in which we detect 8 events in 614 seconds,
with a mean background expectation of 0.34 counts.  This results in a rate
of 1.48 (+0.6, -0.5) e-2 counts/s (1 sigma errors).

In the 2nd epoch (T0+4 ks to T0+80 ks), we detect 3 events in 7.2 ks, with
an expected background of 1.25 events, giving a 3 sigma upper limit of
< 0.002 counts/s.

In the 3rd epoch (T0+171 ks to T0+206 ks), we find 5 events in 4.8 ks with a
mean background expectation of 0.64 events, giving a 3 sigma detection
of 1.2 (+0.8, -0.6) e-3 counts/s (1 sigma errors).

All measurements use a source radius of 9 pixels (21 arcseconds),
a background measurement from an annulus around the source region, and
the Bayesian method of Kraft, Burrows, and Nousek (1991, ApJ, 374, 344) to obtain
the 1-sigma confidence intervals (for detections) or 3-sigma upper limits (for non-detections).

Therefore, after a detection in the initial XRT observation, the source
faded below the XRT detection limit and may have brightened again
in the 3rd epoch.

We cannot conclude firmly at this point whether the source
[PFH2005] 622 is associated with the BAT trigger or not.
More observations at all wavelengths are encouraged.

A table and a light curve that summarize current XRT observations
of [PFH2005] 622 are available at:
http://swift.gsfc.nasa.gov/results/BATbursts/633105/xrt/atel_20150304.html

[GCN OPS NOTE(05mar15), Per author's request, the last line in the 5th paragraph
was changed from "the 3 sigma confidence regions and upper limits."
to "the 1-sigma confidence intervals (for detections) or 3-sigma upper limits (for non-detections).".
And the places in the 2nd & 4th paragraphs that said "(1 sigma errors)"
were changed to "(1 sigma errors)".]


GRB_name: GRB150301C
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17545
SUBJECT: GRB 150301C: VLA Observations
DATE:    15/03/04 23:18:10 GMT
FROM:    Tanmoy Laskar at Harvard U  <tanmoylaskar@gmail.com>

T. Laskar, E. Berger (Harvard) and D. Fox (PSU) report on behalf of a larger
collaboration:

"We observed GRB 150301C (Lien et al; GCN 17512) with the VLA beginning on 2015
March 04.03 UT (2.77 days after the burst) at a mean frequency of 9.8 GHz.
No radio counterpart is detected in the 90-minute observation within the
XRT error circle (Evans et al; GCN 17536) to a 3 sigma upper limit of 18
uJy. The 90-minute observation covers the full BAT error circle and does not
contain any radio source brighter than the NVSS flux limit. Well-detected
sources fainter than the NVSS limit have been identified for possible
future monitoring. We thank the VLA staff for scheduling and obtaining
these observations."


GRB_name: GRB150301C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17547
SUBJECT: Further UVOT Observations of Swift J0045.2+4151
DATE:    15/03/06 00:54:19 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel, L.M.Z. Hagen (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift UVOT team:

Swift continues to observe the field of BAT trigger 633105 (formerly
GRB 150301C, now Swift J0045.2+4151) with a sky location in M31.
The UVOT data show no change in brightness in the optical source reported
in Hagen & Lien (GCN Circ 17541). 

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

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

v            338602      338728        124    >18.25
b            337955      338082        124    >19.12
u            337824      337951        124     18.45+-0.27
uvw1         337564      337819        250     18.82+-0.26
uvm2         326044      343973       4048     18.64+-0.06
uvw2         338088      338597        500     18.72+-0.14

All of these magnitudes are consistent, within uncertainties, of 
our initial and archival measures.

We further report an analysis of 207 ks of archival UVOT data for
the source.  Our analysis shows no previous variability in the source
in the UVOT photometry, which has a typical uncertainty of 0.2 mag in
the three UV filters.


GRB_name: GRB150301C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17548
SUBJECT: Swift J0045.2+4151: analysis of XMM-Newton archival data
DATE:    15/03/06 15:28:51 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

A. Belfiore (INAF/IASF Milano), A. Tiengo (IUSS Pavia), G. L. Israel 
(INAF/OA Roma), A. M. Read (U. Leicester), R. Salvaterra, D. Salvetti 
(INAF/IASF Milano), G. Novara (IUSS Pavia), S. Mereghetti, M. Marelli 
(INAF/IASF Milano), G. Rodriguez (INAF/OA Roma), G. Lisini (IUSS Pavia), 
S. R. Rosen (U. Leicester), A. De Luca  (INAF/IASF Milano), report on 
behalf of the EXTraS collaboration:

Based on the preliminary results of the EXTraS project (DeLuca et al. 
2015, arXiv:1503.01497), we report on the analysis of XMM-Newton archival 
data of 3XMM J004514.7+415035 (aka [PFH2005] 622, Pietsch et al. 2005, ApJ 
434, 483), the candidate X-ray counterpart of GRB 150301C  (aka Swift 
J0045.2+4151, GCN Circ 17512, 17516, 17536, 17544). The source is detected 
by the EPIC instrument at a 0.2-12 keV flux level of ~10^-14 erg/cm^2/s in 
two observations (2002-01-26 and 2007-01-05), while only upper limits of 
~5x10^-14 erg/cm^2/s can be set from 5 shorter observations performed in 
July 2006. Shallow upper limits of ~10^-12 erg/cm^2/s can be derived from 
three non-detections during slew observations on 2005-07-03, 2007-01-06, 
and 2010-01-31.

The EPIC light curves of the two observations show no evidence for 
variability. The search for coherent pulsations in the PN data, between 
0.15 and 10^4 s, gives negative results. The blind search for transients 
does not report any significant candidates within the BAT error circle of 
GRB 150301C in any of the seven XMM-Newton observations.

We extracted the EPIC spectra of 3XMM J004514.7+415035 and, after 
verifying that there are no significant spectral differences between the 
two observations, we fit them simultaneously with an absorbed power-law 
model. The best-fit parameters (errors at the 90% confidence level) are 
N_H<3x10^21 cm^-2 and photon index 1. 9 (-0.6, +0.8). Fixing the N_H to 
the Galactic value of 10^21 cm^-2, as appropriate for sources in the M31 
disk, the photon index can be constrained in the 1.6-2.2 range (C-stat=142 
for 143 degrees of freedom) and the unabsorbed flux in the 0.1-10 keV 
range is (1.3 +/- 0.3) x10^-14 erg/cm^2/s, corresponding to ~6x10^35 erg/s 
at the M31 distance.

We note that the properties of 3XMM J004514.7+41503 are consistent with 
those of an active magnetar, like, e.g., SGR1806-20, at the distance of 
M31. Considering that the duration, fluence and spectrum of the burst 
detected by BAT are compatible with an intermediate flare from a magnetar 
in M31, 3XMM J004514.7+41503 might be considered as a magnetar candidate 
in the Andromeda galaxy.

Plots of the long term flux evolution, the background-subtracted and 
exposure-corrected light curves, and the power density spectra with pulsed 
fraction upper limits can be found on the EXTraS website: 
http://www.extras-fp7.eu/index.php/home/90-extras/news/158-gcn-atel-1

EXTraS ("Exploring the X-ray Transient and variable Sky") is a project 
aimed at the systematic exploitation of the XMM/EPIC database, to search 
for, and characterize variability (both periodic and aperiodic), to search 
for new transients and to provide a phenomenological classification of 
variable sources. All EXTraS results, products and tools will be released 
to the community at the end of the project. EXTraS is carried out by a 
collaboration including INAF (Italy), IUSS (Italy), CNR/IMATI (Italy), 
University of Leicester (UK), MPE (Germany) and ECAP (Germany) and has 
been funded within the EU-FP7 framework (grant agreement n. 607452).


GRB_name: GRB150301C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17549
SUBJECT: Chandra X-ray observations of SWIFT J0045.2+4151 (aka Sw J0045 aka GRB 150301C aka p[PFH2005] 622)
DATE:    15/03/07 22:09:02 GMT
FROM:    David Burrows at PSU/Swift  <dnburrows@gmail.com>

Kari A. Frank (PSU), David N. Burrows (PSU), Alessandro Maselli (INAF-IASFPA), Phil Evans (U. Leicester), Chryssa Kouveliotou (GWU), Ersin Gogus (Sabanci Univ.), Daniele Malesani (DARK/NBI):


On Friday, March 6, 2014, beginning at 2015-03-06T16:29:31 (T0+468.4 ks relative to the Swift BAT trigger) we obtained a Chandra DDT observation at the position of the XMM-Newton source [PFH2005] 622 (Pietsch et al. 2005, ApJ 434, 483, ATel #7181), coincident with the BAT source SWIFT J0045.2+4151 (GCN #17512, GCN #17516, ATel #7166, ATel #7176).  Net exposure time was 9.94 ks. The source was detected at the > 10 sigma level, with a count rate of 0.0023 (-0.0011,+0.0012) counts/s in the 0.5-8 keV band (errors are 90% confidence).    

The Chandra source position is:

RA(J2000) = 00h 45m 14.78s
Dec(J2000) = +41d 50m 34.53s

with a 90% uncertainty of 0.8 arcsec.  A total of 23 source counts were detected. This position is consistent with the XMM position of [PFH2005] 622 and the XRT position (ATel #7166).

Assuming a powerlaw spectrum with photon index of 2, we find a flux 2.05e-14 (-0.97,+1.07) erg/cm^2/s (errors are 90% confidence).  This is about 10 times fainter than the flux measured in the first XRT observation (ATel #7166), and similar to the archival XMM fluxes for [PFH2005] 622 reported in ATel #7181, though it is brighter than the 6.9e-15 erg/cm2/s reported by Pietsch et al. (2005).

At the distance of M31, the observed flux corresponds to a luminosity of 9.5e35 erg/s.


GRB_name: GRB150305A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17551
SUBJECT: GRB 150305A: Swift XRT confirms weak INTEGRAL event as a new GRB
DATE:    15/03/08 18:12:17 GMT
FROM:    Rhaana Starling at U of Leicester  <rlcs1@star.le.ac.uk>

R. Starling (U. Leicester) reports:

On 2015-03-05T09:49:19 UT INTEGRAL recorded a 7.6 sigma event at 
RA, Dec 269.78943, -41.62041 degrees (err 3.39 arcmin) and issued WEAK 
Alert 6905. We triggered a Swift ToO to observe this position.

Swift observations began at 1.8E4 s after the INTEGRAL trigger with 
exposure time 3ks (obsID33663). Two sources were present in the error circle.
One of these is consistent with the ROSAT source 1RXS J175914.5-423529, 
which is likely associated with dwarf nova V728 CrA.

The second is a new source, with enhanced XRT position of
RA, Dec (J2000) = 17h 59m 02.60s, -42$B!k(B 39$B!l(B 49.5$B!l!l(B (269.76082, -42.66374 deg) 
with an uncertainty of 3.3$B!l!l(B (radius, 90% confidence).

In this first observation the new source had a count rate 0.035 ct/s.
Further Swift observations beginning 1.1E5s post-burst with exposure time 
3.7ks showed that this source had a count rate of approx. 0.007 ct/s, having 
faded with a decay rate of alpha ~ -0.7. 

The spectrum of the new source can be described with an absorbed power law.

The UVOT data were taken in UVM2 and UVW1 filters. A preliminary analysis 
does not reveal any UV counterpart to the new XRT source.

We conclude that the INTEGRAL WEAK event was a real GRB and that the 
fading source discovered by Swift XRT is the afterglow.

We thank the Swift team for carrying out these ToOs, and acknowledge use
of the UK Swift Science Data Centre in our analysis.


GRB_name: GRB150305A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17552
SUBJECT: GRB 150305A: a long GRB detected by INTEGRAL
DATE:    15/03/09 12:41:36 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

S.Mereghetti (IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo 
(ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of the IBAS 
Localization Team report:

a gamma ray burst lasting at least 100 s has been detected by IBAS in the 
IBIS/ISGRI data at 09:49:19 UT of March 5, 2015.

The refined coordinates (J2000) are:

R.A.= 269.7685 deg
DEC.= -42.6481  deg

with an uncertainty of  2.5   arcmin (90% c.l.).

The burst had a peak flux of about 0.2 counts/cm2/s (20-200 keV, 1-s 
integration time) and a fluence in the same energy range of about 7e-7 
erg/cmq (over 100 s).

Due to the significance of the detection below the high confidence 
threshold, only an Alert Packet of WEAK type was distributed by IBAS in 
real time (Packet n. 6905). The X-ray afterglow has been detected with 
Swift/XRT (Starling 2015, GCN 17551).

A plot of the light curve can be found at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html


GRB_name: GRB150309A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17553
SUBJECT: GRB 150309A: Swift detection of a burst
DATE:    15/03/09 23:17:18 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL)
report on behalf of the Swift Team:

At 23:03:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150309A (trigger=634200).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 276.987, +86.430, which is 
   RA(J2000)  =  18h 27m 57s
   Dec(J2000) = +86d 25' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a peak around T+30 sec
with a duration of about 60 sec.  The peak count rate
was ~200 counts/sec (15-350 keV), at ~45 sec after the trigger. 

The XRT began observing the field at 23:05:18.2 UT, 131.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 277.08842, 86.42988 which
is equivalent to:
   RA(J2000)  = 18h 28m 21.22s
   Dec(J2000) = +86d 25' 47.6"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 22 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 in excess of the Galactic value (9.05 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.4
(+3.89/-3.10) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 2.73e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 140 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
0.14. 

Burst Advocate for this burst is J. R. Cummings (jayc 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: GRB150309A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17554
SUBJECT: GRB 150309A: BOOTES-1 and -2 upper limit
DATE:    15/03/10 00:13:17 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

R. Cunniffe, M. Jelinek, Y. Hu, S. Jeong, S. R. Oates (IAA-CSIC), B.-B. Zhang
(IAA-CSIC and UAH) and A. J. Castro-Tirado (IAA-CSIC and ISA-UMA), on behalf of a
larger collaboration, report:

Both the 60 cm BOOTES-2/TELMA and the 30 cm BOOTES-1 robotic telescopes in
South Spain automatically responded to the Swift trigger of GRB 150309A
(Cummings et al., GCN 17553). The first exposure started at 23:04:33 UT
(86s after the trigger) and a sequence of 20 images was obtained (3s each,
clear filter). A median combined image revealed no optical counterpart at
the enhanced XRT error circle down to 18 mag. Further observations are
ongoing.

[GCN OPS NOTE(10mar15): Per author's request, the affilliation of B-BZ was changed.]


GRB_name: GRB150309A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17555
SUBJECT: GRB 150309A: Enhanced Swift-XRT position
DATE:    15/03/10 09:14:30 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 853 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 150309A, 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 = 277.10213, +86.42875 which is equivalent
to:

RA (J2000): 18h 28m 24.51s
Dec (J2000): +86d 25' 43.5"

with an uncertainty of 1.5 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: GRB150309A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17556
SUBJECT: GRB 150309A : Liverpool Telescope observations
DATE:    15/03/10 11:07:36 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri (INAF-OAB), D. Kopac (LJMU), R. J. Smith (LJMU), C. G. Mundell (U. Bath) and A. Gomboc (U. Ljubljana), on behalf of a large collaboration report:

The 2-m Liverpool Telescope robotically followed up Swift GRB 150309A (Cummings et al., GCN 17553) at 23:06:37 UT (~3.5 min after the burst trigger).

No optical counterpart is detected at the enhanced XRT error circle (Osborne et al., GCN 17555) down to r > 19.5 mag (~37 min after burst).


GRB_name: GRB150309A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17557
SUBJECT: GRB 150309A: Swift-XRT refined Analysis
DATE:    15/03/10 11:17:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), K.L. Page (U.
Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA),
D.N. Burrows (PSU) and J.R. Cummings report on behalf of the Swift-XRT
team:

We have analysed 6.9 ks of XRT data for GRB 150309A (Cummings et al.
GCN Circ. 17553), from 122 s to 17.9 ks after the  BAT trigger. The
data comprise 273 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. 17555).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.11 (+0.09, -0.07), followed by a break at T+477 s to
an alpha of 0.98 (+/-0.04).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.82 (+/-0.07). The
best-fitting absorption column is  2.03 (+0.28, -0.27) x 10^21 cm^-2,
in excess of the Galactic value of 9.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.91 (+0.12, -0.11)
and a best-fitting absorption column of 2.8 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.9 x 10^-11 (5.4 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.8 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 9.1 x 10^20 cm^-2
Excess significance: 6.6 sigma
Photon index:      1.91 (+0.12, -0.11)

If the light curve continues to decay with a power-law decay index of
0.98, the count rate at T+24 hours will be 0.022 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.4 x
10^-13 (1.2 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/00634200.

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


GRB_name: GRB150309A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17558
SUBJECT: GRB 150309A: MASTER prompt optical observation 
DATE:    15/03/10 11:53:50 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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

V.Krushinsky,
Ural Federal University, Yekaterinburg, 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 ( Lipunov et al., Advances in Astronomy, vol. 
2010, pp. 1-7, MASTER Global Robotic Net, 2010) 
located in Kislovodsk was pointed to the  GRB150309A 21 sec after notice 
time and 96 sec after trigger time at 2015-03-09 23:04:45 UT in two 
polarizations. On our first (20s exposure)  set we not  found  optical 
transient within SWIFT error-box (Cummings et al GCN 17553) brighter then 
17.2

Before this, the MASTER serial pointed to  FERMI (trig. N 447634793) 
coordinates. Due to this pointings we have a two images from MASTER VWF 
very wide fild camera  obtained at 2015-03-09 23:00:34 i.e. 152 sec before 
SWIFT BAT and  44 sec after FERMI GBM trigger times. We not found new OT 
on this 5 sec exposure images with upper limit 12.0 at SWIFT position.

Table 1. GRB 150309A MASTER optical upper limits.

Tstart  Tst-T0 Tmid-T0 Expt Mlimit  Instrum.   Coadd.
23:00:34  -152    -149    5 12.0    MASTER VWF   no
23:04:45    98     108   20 17.2    MASTER II    no
23:04:45    98     559  780 19.3    MASTER II    10
23:20:20  1033    2363 2160 20.0    MASTER II    12

T0 - is a SWIFT trigger time.

The message may be cited.


GRB_name: GRB150309A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17559
SUBJECT: GRB 150309A: Swift/UVOT Upper Limits
DATE:    15/03/10 13:16:03 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150309A
140 s after the BAT trigger (Cummings et al., GCN Circ. 17553).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 17555)
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           140          290          147         >20.3
u_FC               299          549          246         >19.4
white              140        12463          881         >21.1
v                  630         6293          432         >19.3
b                  555        12046         1121         >20.8
u                  299        17720         2241         >21.1
w1                 679        16806         1318         >20.8
m2                 654         6498          432         >20.1
w2                 605         6089          432         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB150309A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17560
SUBJECT: GRB150309A: Optical observations at Crni Vrh
DATE:    15/03/10 14:27:29 GMT
FROM:    Herman Mikuz at OCV  <herman.mikuz@fmf.uni-lj.si>

B. Dintinjana, S. Maticic and H. Mikuz on behalf of PIKA observing 
program at Crni
Vrh Observatory.

We observed the field of GRB 150309A (Cummings et al., GCN 17553) from 
Crni Vrh Observatory with a 60 cm robotic telescope and clear filter. 
Twenty six consecutive exposures of 60 second duration were taken in 
moonlight conditions. First exposure started at 2015-03-09 23:05:34 UT, 
68 seconds after the SWIFT trigger.

No optical candidate was detected within the uncertainty radius on 
single exposures, having limiting magnitude 19.2, calibrated against the 
nerby USNO-B R2 magnitude stars. Also we found no optical candidate on 
26 sumed unfiltered images with total exposure of 1560 seconds and 
limiting magnitude 20.8 (calibrated against the nerby USNO-B R2 
magnitude stars).


GRB_name: GRB150309A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17561
SUBJECT: GRB 150309A: Fermi GBM detection
DATE:    15/03/10 15:13:46 GMT
FROM:    Oliver Roberts at UCD/Fermi  <oliver.roberts@ucd.ie>

O.J Roberts (UCD) and M. Stanbro (UAH) report on behalf
of the Fermi GBM Team:

"At 22:59:50.66 UT on the 9th of March 2015, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 150309A (trigger 447634793/150309958), the second
episode of which was also detected by Swift
(Cummings et al. 2015, GCN 17553). The GBM on-ground
location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 60 degrees.

The Swift trigger is observed in the GBM light curve at
T0+200 s as a very soft, weak event with a duration of
about 60 s. The immediate light curve at the GBM trigger
time consists of a bright, main peak of unresolved emission
episodes, with a duration (T90) of about 52 s (50-300 keV).
The time-averaged spectrum from T0+0.0 s to T0+52.6 s is
best fit by a Band function with Epeak= 165 +/- 4 keV,
alpha = -0.59 +/- 0.02 and beta = -2.59 +/- 0.10.

The event fluence (10-1000 keV) in this time interval is
(3.9 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+17.5 s in the 10-1000 keV band
is 15.2 +/- 0.3 ph/s/cm^2.

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


GRB_name: GRB150309A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17562
SUBJECT: GRB 150309A: Swift-BAT refined analysis
DATE:    15/03/10 19:58:42 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+471 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150309A (trigger #634200) (Cummings, et
al., GCN Circ. 17553).  The BAT ground-calculated position is
RA, Dec = 277.004, 86.417 deg which is
   RA(J2000)  =  18h 28m 01.0s
   Dec(J2000) = +86d 25' 02.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows that the main peak of the burst, which
occurred during a Swift preplanned slew maneuver, started at about T-200 seconds.
The roughly symmetrical peak with multiple maxima lasted until about T-160
seconds.  A weaker overlapping peak followed at about T-150 seconds and declined
to background by about T-60 seconds.  BAT triggered on a smaller peak that lasted
from about T+0 seconds to about T+120 seconds.  T90 (15-350 keV) is
242 +- 6 sec (estimated error including systematics).  Because the source came
into the BAT field of view during the slew, it is possible that there was some
additional low-level emission before T-200 seconds.

The time-averaged spectrum from T-197.32 to T+119.08 sec is best fit by a power
law with an exponential cutoff.  This fit gives a photon index 1.05 +- 0.16,
and Epeak of 175.8 +- 76.0 keV (chi squared 37.47 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.7 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T-177.49 sec in the 15-150 keV band is
9.0 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.36 +- 0.04 (chi squared 49.55 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/634200/BA/


GRB_name: GRB150309A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17564
SUBJECT: GRB 150309A: ISON-Kislovodsk optic upper limit
DATE:    15/03/11 12:35:27 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Vazaeva (IKI), V. Nevskiy (ISON), A. Volnova (IKI), I. Molotov 
(KIAM), A. Pozanenko (IKI),report on  behalf of larger collaboration:

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553) with Santel-400AN   telescope of ISON-Kislovodsk observatory 
starting on Mar. 09 (UT) 23:11:26, i.e. ~8.5 min after the burst 
trigger. In the enhanced XRT position (Osborne et al., GCN 17555) we do 
not detect any object. An upper limit is following

Date       UT start   t-T0    Filter   Exp.     UL(3 sigma)
                      (mid, days)        (s)

2014-09-03 23:11:26  0.02590  None     49*60    20.0

The photometry is based on USNO-B1.0 star

USNO-B1.0_id  R2

1764-0030460  15.42


GRB_name: GRB150309A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17565
SUBJECT: GRB 150309A: CrAO optic upper limit
DATE:    15/03/11 12:55:33 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Rumyantsev (CrAO), K. Antoniuk, E. Mazaeva (IKI),  A. Pozanenko (IKI) 
report on  behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553) with AZT-11 telescope of CrAO observatory starting on Mar. 09 
(UT) 23:39:47. We took several images in R-filter of 180 s exposure. In 
the enhanced XRT position (Osborne et al., GCN 17555) we do not detect 
any object. An upper limit is following

Date       UT start,  t-t0     Filter   Exp.      UL (3 sigma)
                       (mid, days)        (s)

2015-03-09 23:39:47   0.0468   R        20*180    20.9

The photometry is based on nearby USNO-B1.0  stars.


GRB_name: GRB150309A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17566
SUBJECT: Konus-Wind observation of GRB 150309A
DATE:    15/03/11 13:08:42 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long-duration GRB 150309A (Swift-BAT trigger #634200:
Cummings et al., GCN 17553; Baumgartner et al., GCN 17562)
triggered Konus-Wind at T0=82792.708 s UT (22:59:52.708).

The KW light curve shows a broad emission pulse which
starts at ~T0-7 s and decays to ~T0+55 s.
The pulse is followed by a weak soft emission detectable
up to ~T0+250 s.
The emission is visible up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150309_T82792/

As observed by Konus-Wind, the burst had a fluence
of 4.1(-0.4,+0.5)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+16.832 s, of 4.0(-0.4,+0.4)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+53.248 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 = -0.79 (-0.09,+0.11),
the high energy photon index beta = -2.79 (-0.48,+0.29),
the peak energy Ep = 182 (-17,+14) keV,
chi2 = 101/97 dof.

The spectrum near the peak count rate
(measured from T0+8.448 to T0+20.480 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 = -0.64 (-0.09,+0.11),
the high energy photon index beta = -2.73 (-0.34,+0.22),
the peak energy Ep = 197 (-17,+16) keV,
chi2 = 110/97 dof.

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150222A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17567
SUBJECT: GRB 150222A: CrAO optical observation
DATE:    15/03/11 21:13:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the Swift GRB GRB 150222A (Bernardini et al., 
GCN 17486) with ZTSh telescope of CrAO observatory starting on
Feb. 22 (UT) 23:19:54. We took several images in R-filter of 120 s 
exposure under non-optimal weather conditions and mean seeing of 4". 
Within enhanced  XRT position (Beardmore et al., GCN 17494) we detect a 
source in coordinates (J2000) 13 15 08.74 -12 09 07.2 with uncertainty 
of 0.4 arcsec in both coordinates. The source position is coincident 
with the optical afterglow candidate (Nicuesa Guelbenzu et al., GCNs 
17495, GCN 17506).  Photometry of the source in a combined image is 
following

Date       UT start,  t-t0     Filter   Exp.    OT   OT_err UL(3sigma)
                       (mid, days)        (s)

2015-02-22 23:19:54   0.2913   R        34*120  23.0 0.3    23.3

The photometry is based on USNO-B1.0  star 0778-0337957 (J2000) 13 15 
05.41 -12 08 17.5 assuming R2=15.31

Taking into account photometry of the source r' = 24.6+/-0.3 at ~0.42 
days reported by Nicuesa Guelbenzu et al. (GCN 17495) one could suggest 
the source is the optical afterglow of GRB 150222A.

The source reported in GCN 17489 (Mazaeva et al) is clearly visible in 
coordinates (J2000) 13 15 08.30 -12 08 57.5 with uncertainty of 0.4 
arcsec in both coordinates. A photometry of the source is R=22.12+/-0.12.


GRB_name: GRB150311A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17568
SUBJECT: GRB 150311A: MAXI/GSC possible afterglow detection
DATE:    15/03/12 05:16:34 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

M. Morii (RIKEN), H. Negoro (Nihon U.), M. Serino (RIKEN),
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, D. Uchida (Osaka U.),
M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.),
M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 2015-03-11T16:18:16 UT .
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (235.099 deg, -15.809 deg) = (15 40 23, -15 48 32) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.27 deg and 0.26 deg, respectively.
The roll angle of long axis from the north direction is 79.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 93 +- 20 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 14:45
and in the next transit at 17:50 UT with an upper limit of 20 mCrab for each.

According to GCN IPN_RAW Notices, The Konus-Wind instrument triggered at
16:16:24.88, which is 111s before the MAXI trigger.
Therefore MAXI might have observed the afterglow of GRB 150311A triggered by
Konus-Wind, while the position of this burst is not known.


GRB_name: GRB150311A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17569
SUBJECT: GRB 150311A: Konus-Wind trigger at 16:16:24 is not a GRB
DATE:    15/03/12 10:03:19 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, on behalf of the Konus-Wind team, reports:

The Konus-Wind trigger at 16:16:24.884 mentioned by Morii et al. (GCN 17568), 
which is 111 s before the MAXI trigger, is actually due to a X2.1 class solar
flare. Therefore, taking into account the MAXI localization of the source,
we suggest that the Maxi trigger is unrelated to the Konus-Wind trigger.


GRB_name: GRB150309A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17570
SUBJECT: GRB 150309A: AAO optic upper limit
DATE:    15/03/12 18:16:20 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO),   A. 
Volnova (IKI), Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553)  with AS-32 (0.7m) telescope of Abastumani Observatory starting 
on Mar. 10 (UT) 01:40:54.  Within the enhanced XRT position (Osborne et 
al., GCN 17555) we do not detect any object. An upper limit is following

Date       UT start   t-T0    Filter   Exp.     UL(3 sigma)
                      (mid, days)        (s)

2015-03-10 01:40:54  0.12699  None     19*120   21.2

The photometry is based on USNO-B1.0 star

USNO-B1.0_id  R2

1764-0030460  15.42


GRB_name: GRB150313A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17572
SUBJECT: GRB 150313A: MAXI/GSC detection
DATE:    15/03/13 09:16:13 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

Y. Morooka (Miyazaki U.), M. Serino (RIKEN), H. Negoro (Nihon U.), S. Nakahira (JAXA),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, D. Uchida (Osaka U.),
M. Nakajima,  K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.),
M. Yamauchi, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray 
transient source at 03:52:04 UT.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (251.439 deg, -11.707 deg) = (16 45 45, -11 42 24) (J2000)
(R.A., Dec) = (251.141 deg, -11.484 deg) = (16 44 33, -11 29 03) (J2000)
(R.A., Dec) = (253.294 deg, -9.249 deg) = (16 53 10, -09 14 55) (J2000)
(R.A., Dec) = (253.579 deg, -9.484 deg) = (16 54 18, -09 29 03) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 226 +- 34 mCrab
(4-10keV, 1 sigma error).
Because the duration of this burst is short (about 5 s in 4-10 keV),
the flux above is underestimated and it might be as high as 7 Crab.
There was no significant excess flux in the previous transit at 02:19 UT
and in the next transit at 05:24 UT 
with an upper limit of 20 mCrab for each.


GRB_name: GRB150314A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17573
SUBJECT: GRB 150314A: Swift detection of a bright burst
DATE:    15/03/14 05:15:27 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

L. M. Z. Hagen (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:

At 04:55:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150314A (trigger=634795).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 126.659d, +63.833d which is 
  RA(J2000) = 08h 26m 38s
  Dec(J2000) = +63d 50' 00"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single complex peak
structure with a duration of about 15 sec.  The peak count rate
was ~45000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 04:56:17.9 UT, 85.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 126.6756, 63.8321 which is equivalent to:
   RA(J2000)  = +08h 26m 42.14s
   Dec(J2000) = +63d 49' 55.6"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 26 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 data is not immediately available. 

Burst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen AT gmail.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: GRB150314A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17574
SUBJECT: GRB 150314A: KAIT Optical Candidate
DATE:    15/03/14 05:40:52 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150314A (Hagen et al.,
GCN 17573) starting at 04:57:32 UT, 136 s after the burst. We
detect a fading source at position
RA=  08:26:40.96 (J2000)
DEC= 63:50:03.20 (J2000)
which faded from mag R~16.0 to R~17.5 in a time interval of about 10
minutes. We suggest this to be the optical afterglow of GRB 150314A.
However, we note that this position is about 11 arcsecond, a bit far
away from XRT position, indicating this might be unrelated source.
Observations are on going.


GRB_name: GRB150314A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17575
SUBJECT: GRB 150314A: Enhanced Swift-XRT position
DATE:    15/03/14 09:26:44 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 2271 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 150314A, 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 = 126.67042, +63.83429 which is equivalent
to:

RA (J2000): 08h 26m 40.90s
Dec (J2000): +63d 50' 03.5"

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: GRB150314A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17576
SUBJECT: GRB 150314A: Fermi-LAT detection
DATE:    15/03/14 14:02:47 GMT
FROM:    Magnus Axelsson at Stockholm U.  <magaxe@kth.se>

M. Axelsson (KTH Royal Institute of Technology, Sweden), D. Kocevski (NASA/GSFC)
and J. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team:

At 04:54:50.9 UT on March 14, 2015, Fermi-LAT detected
high-energy emission from GRB 150314A, which was also detected by Fermi-GBM
(trigger 448001693/150314205) and Swift (Hagen et al., GCN 17573), and a possible
optical counterpart by KAIT (Zhang et al., GCN 17574).

The best LAT on-ground location is found to be

RA, Dec 125.40, 64.46 (J2000)

with an error radius of 0.85 deg (90% containment, statistical error only) and consistent
with the Swift/XRT location. This was ~40 deg from the LAT boresight at the time of the
trigger and triggered an autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate within 10 degrees
of the Swift/XRT location after the trigger. More than 14 photons above 100 MeV are observed
within 500 seconds. The highest-energy photon is a 670 MeV event which is
observed 78 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is
Magnus Axelsson (magnus.axelsson@astro.su.se<mailto:magnus.axelsson@astro.su.se>).

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: GRB150314A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17577
SUBJECT: GRB 150314A: Skynet Yerkes-41 Observations of the Optical Afterglow
DATE:    15/03/14 14:04:24 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, A. LaCluyze, J. Haislip, V. Hoette, K. Cudworth, D. Harper, R. Kron, T. Linder, R. Russell, E. Struble, A. Aji, T. Berger, A. Dow, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, C. Salemi, and J. A. Crain report:

Skynet observed the Swift BAT/XRT localization of GRB 150314A (Hagen et al., GCN 17573, Swift trigger=634795) with the 41" telescope at Yerkes Observatory in WI, USA, starting at 2015-03-14 04:58:22 (t=3.5m post-trigger) and continuing until t=41m post-trigger. Skynet took a total of 17 exposures ranging from 20s to 160s in the g', r' and i' bands. We detect a fading source in all three bands at the position reported by Zheng & Filippenko (GCN 17574).

A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb150314a.png

Magnitudes are in the AB System, calibrated to 4 APASS stars in the field.  Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.035 (Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.


GRB_name: GRB150314A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17578
SUBJECT: GRB 150314A: MITSuME Akeno upper limits 
DATE:    15/03/14 14:14:18 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano,
S. Kurita, Y. Ono, T. Fujiwara, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 150314A (L. M. Z. Hagen et al., GCN Circular #17573) 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 at 2015-03-14 05:21:32 UT (~5.4 h after the burst).
We could not find any new point source within the refined XRT-UVOT alignment error circle 
(A.P. Beardmore et al., GCN Circular #17575) in all the three bands.

The obtained upper-limits are listed below.

T0+[sec]     MID-UT    T-EXP[sec]        g'         Rc        Ic
-----------------------------------------------------------------------------
19292        11:19:44        6840          >21.6  >21.1  >20.1
-----------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB150314A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17579
SUBJECT: GRB 150314A: Fermi GBM observation
DATE:    15/03/14 15:30:39 GMT
FROM:    Hoi-Fung Yu at MPE  <sptfung@mpe.mpg.de>

H.-F. Yu (MPE) reports on behalf of the Fermi GBM Team:

"At 04:54:50.85 UT on 14 Mar 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150314A (trigger 448001693 / 150314205),
which was also detected by the Swift (Hagen et al. 2015, GCN 17573)
and Fermi LAT (Axelsson et al. 2015, GCN 17576). The GBM on-ground
location is consistent with the Swift position. The trigger resulted
in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location. The initial angle
from the Fermi LAT boresight is about 50 degrees.

The GBM light curve shows a bright single pulse with a duration (T90)
of about 10.7 s (50-300 keV). The time-averaged spectrum from
T0+0.002 s to T0+13.472 s is best fit by a Band function with
Epeak = 311 +/- 5 keV, alpha = -0.60 +/- 0.01, and beta = -2.32 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(8.53 +/- 0.04)E-05 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+2.144 s in the 10-1000 keV band
is 67.1 +/- 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: GRB150314A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17580
SUBJECT: GRB 150314A: Swift/UVOT Detection
DATE:    15/03/14 18:04:29 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150314A
95 s after the BAT trigger (Hagen et al., GCN Circ. 17573). We detect
a fading source consistent with the XRT position (Beardmore et al.
GCN Circ. 17575) and optical detections (Zheng & Filippenko GCN Circ.
17574, Trotter et al. GCN Circ. 17577) that is detected in all but the
bluest UVOT filters.

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               97          244          144         17.22 +/- 0.03
white              587          781           38         19.13 +/- 0.18
white             5472         5671          196        >21.02
v                   75           85            9         15.48 +/- 0.13
v                  637          657           19         17.75 +/- 0.33
v                 4445         6082          390        >19.77
b                  562          756           38         19.28 +/- 0.35
b                 5266         5466          196        >20.32
u                  307          556          245         18.86 +/- 0.14
u                  712         6528          253        >20.14
uvw1               687         6485          412        >20.31
uvm2              4650         6280          391        >20.16
uvw2               613         5877          412        >20.46

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: GRB150314A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17581
SUBJECT: GRB 150314A Swift-BAT refined analysis
DATE:    15/03/14 19:19:53 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC),  L. M. Z. Hagen (PSU), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150314A (trigger #634795)
(Hagen, et al., GCN Circ. 17573).  The BAT ground-calculated position is
RA, Dec = 126.661, 63.839 deg which is
  RA(J2000)  =  08h 26m 38.6s
  Dec(J2000) = +63d 50' 21.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 34%.

The mask-weighted light curve shows a single bright FRED pulse that starts at
~ T-2 s, peaks at ~T0, and ends at  ~T+13 s. There are some weak extended
emissions that last till ~ T+100 s. T90 (15-350 keV) is 14.79 +- 2.64 sec (estimated
error including systematics).

The time-averaged spectrum from T-2.17 to T+101.42 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.08 +- 0.03.  The fluence in the 15-150 keV band is 2.2 +- 0.03 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+0.06 sec in the 15-150 keV band
is 38.5 +- 0.9 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/634795/BA/


GRB_name: GRB150314A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17582
SUBJECT: GRB 150314A: NOT optical observations
DATE:    15/03/14 22:13:53 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), S. Geier
(GTC/IAC), K. E. Heintz, J. P. U. Fynbo, D. Malesani (DARK/NBI), P.
Jakobsson (U. Iceland) report on behalf of a larger collaboration:

We observed the field of GRB 150314A (Hagen et al., GCN 17573) using
the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC
camera. We obtained 3x300 s R-band images with a median time of
20:48:36 UT on 2015-03-14, i.e., 15.89 hr after the burst, and in a
seeing of ~0.9".

The optical afterglow (Zheng & Filippenko, GCN 17574; Trotter et al.,
GCN 17577) is clearly detected in our stacked image, with m(R)=22.7
+/- 0.3 mag, calibrated with USNO B1 catalog. The object is a bit
extended in the northwest-southeast direction, indicating that the
host galaxy might be emerging at the observational time.


GRB_name: GRB150314A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17583
SUBJECT: GRB 150314A: Redshift from OSIRIS/GTC
DATE:    15/03/14 23:39:25 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J.P.U. Fynbo (DARK/NBI), 
C. Thoene (IAA-CSIC), N.R. Tanvir (U. Leicester),  R. Sanchez-Ramirez 
(UPV, IAA-CSIC), J. Gorosabel (UPV-EHU, IAA-CSIC), P. Pessev (ULL, IAC), 
C. Alvarez Iglesias (ULL, IAC), M.A. Rivero (GRANTECAN) report on behalf 
of a larger collaboration:

We obtained spectroscopy of the afterglow of GRB 150314A (Hagen et al., 
GCN 17573; Zheng & Filippenko, GCN 17574; Axelsson et al., GCN 17576; 
Trotter et al., GCN 17577; Xu et al. GCN 17582) using OSIRIS at the 10.4 m 
GTC telescope in La Palma (Spain). Observations consisted of 3 x 1200 s 
exposure using the R1000B grism, covering the range between 3700 and 
7875 A at a resolution of ~700 (1" slit). The mean observing time was 21:37 UT 
(16.70 hr after the burst).

The spectrum shows a continuum with an average  SNR ~ 7 (per resolution 
element) on which several weak absorption features can be identified. Our 
best match corresponds to lines of FeII, MgII, MgI as well as AlII, AlIII and CIV 
at lower significance, all at a common redshift of 1.758, which we propose as 
the redshift of the GRB.

At this redshift, the isotropic equivalent energy is Eiso = 6.74e53 erg 
considering the fluence reported by Fermi/GBM (Yu et. al GCN 17579) in the 
(10-1000) keV window.


GRB_name: GRB150314A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17584
SUBJECT: GRB 150314A: P60 observations
DATE:    15/03/15 01:06:49 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) and S. B. Cenko (NASA/GSFC) report:

The Palomar 60-inch robotic telescope began automatic follow-up of the
location of GRB 150314A (Hagen et al., GCN 17573) at 05:08:40 UT on 
2015-03-14, 13.4 minutes after the GRB trigger.   A sequence of 
60-second r, i, and z exposures were acquired, lasting until 06:36 UT. 
Another sequence of 180-second g, r, and i exposures was taken between 
09:01 UT and 10:54 UT.

We detect the optical afterglow reported by Zheng and Filippenko (GCN 
17574) in individual exposures from the early sequence as well as in a 
stack of the later-time exposures.  Calibrating to a nearby USNO star 
(RA=126.701423, dec=63.829609,  R2=15.33) gives the following photometry:

t_med = 834s   : R = 18.59 +/- 0.05
t_med = 1179s  : R = 18.96 +/- 0.05
t_med = 1437s  : R = 19.06 +/- 0.07
t_med = 1693s  : R = 19.41 +/- 0.07
t_med = 1977s  : R = 19.59 +/- 0.08
t_med = 18365s : R = 21.73 +/- 0.13

The afterglow fades as approximately t^-0.9 throughout our observations.


GRB_name: GRB150314A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17585
SUBJECT: GRB 150314A: KAIT Optical Observations
DATE:    15/03/15 03:00:02 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150314A (Hagen et al.,
GCN 17573) starting at 04:57:32 UT, 136 s after the burst.
Observations were performed with an automatic sequence in the
clear (roughly R), V, and I filters, and the exposure time was
20 s per image. The afterglow reported by Zheng and Filippenko
(GCN 17574) was detected in clear and I band, but not in V band.
Useful observations lasted for about 20 minutes before the weather
change to be coludy. Preliminary analysis shows that the afterglow
decays with a single power (with alpha = -1.12) from the
beginning of our observations until about a thousand seconds
after the burst. A preliminary light curve is posted at
http://astro.berkeley.edu/~zwk/grb/GRB150314A/GRB150314A_kait.png


GRB_name: GRB150314A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17586
SUBJECT: GRB 150314A: Swift-XRT refined Analysis
DATE:    15/03/15 03:15:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Sbarufatti (INAF-OAB/PSU), C. Pagani (U. Leicester), A.P. Beardmore
(U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), M. de
Pasquale (INAF-IASFPA), A. Maselli  (INAF-IASFPA), D.N. Burrows (PSU),
J.A. Kennea (PSU) and L.M.Z. Hagen report on behalf of the Swift-XRT
team:

We have analysed 8.1 ks of XRT data for GRB 150314A (Hagen et al. GCN
Circ. 17573), from 78 s to 69.2 ks after the  BAT trigger. The data
comprise 690 s in Windowed Timing (WT) mode (the first 6 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 Beardmore
et al. (GCN Circ. 17575).

The late-time light curve (from T0+4.2 ks) can be modelled with an
initial power-law decay with an index of alpha=0.57 (+0.13, -0.20),
followed by a break at T+11.6 ks to an alpha of 2.00 (+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 1.760 (+/-0.026). The
best-fitting absorption column is  1.72 (+0.10, -0.09) x 10^21 cm^-2,
in excess of the Galactic value of 4.5 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.90 (+/-0.10) and a
best-fitting absorption column of 2.3 (+/-0.4) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.9 x 10^-11 (5.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.3 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 4.5 x 10^20 cm^-2
Excess significance: 8.4 sigma
Photon index:      1.90 (+/-0.10)

If the light curve continues to decay with a power-law decay index of
2.00, the count rate at T+24 hours will be 0.019 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x
10^-13 (9.8 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/00634795.

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


GRB_name: GRB150314A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17587
SUBJECT: Konus-Wind observation of GRB 150314A
DATE:    15/03/15 12:48:21 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long-duration, very intense GRB 150314A
(Swift-BAT trigger #634795: Hagen et al., GCN 17572; Cummings et al., GCN 17581;
Fermi-LAT detection: Axelsson et al., GCN 17576;
Fermi-GBM observation: Yu, GCN 17579)
triggered Konus-Wind at T0=17691.727 s UT (04:54:51.727).

The KW light curve shows a bright multi-peaked pulse
with a duration of ~14 s.
The emission is visible up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150314_T17691/

As observed by Konus-Wind, the burst had a fluence
of 9.1(-0.4,+0.4)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+1.344 s, of 2.2(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+12.288 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 = -0.79 (-0.04,+0.04),
the high energy photon index beta = -2.91 (-0.28,+0.18),
the peak energy Ep = 350 (-17,+17) keV,
chi2 = 142/97 dof.

The spectrum near the peak count rate
(measured from T0+0.256 to T0+2.048 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 = -0.37 (-0.08,+0.09),
the high energy photon index beta = -2.81 (-0.27,+0.18),
the peak energy Ep = 348 (-27,+27) keV,
chi2 = 134/94 dof.

Assuming the redshift z=1.758 (de Ugarte Postigo et al., GCN 17583)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~6.9x10^53 erg,
the peak luminosity L_iso is ~4.6x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~965 keV.


All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150314A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17588
SUBJECT: GRB 150314A: NOT further optical observations
DATE:    15/03/16 04:15:19 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D.
Malesani (DARK/NBI), D. Slumstrup (NOT),  P. Jakobsson (U. Iceland)
report on behalf of a larger collaboration:

We continued to observe the field of GRB 150314A (Hagen et al., GCN
17573) using the 2.56m Nordic Optical Telescope (NOT) equipped with
the ALFOSC camera. We obtained 4x600 s R-band images with a median
time of 02:16:32 UT on 2015-03-16, i.e., 45.35 hr after the burst, and
in the seeing of 1.0"-1.5".

The optical afterglow (Zheng & Filippenko, GCN 17574; Trotter et al.,
GCN 17577) is still detected in our stacked image, with m(R) = 23.9
+/- 0.3 mag, calibrated with the same USNO B1 stars that were used in
our previous report (Xu et al., GCN 17582). Together with previous
observations (e.g., Perley & Cenko, GCN 17584; Zheng & Filippenko, GCN
17585), so far the object still nicely fits the decaying law of F(t) ~
t^-0.9.


GRB_name: GRB150220A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17589
SUBJECT: GRB 150220A, the review of the sky area in plate archives
DATE:    15/03/16 14:22:03 GMT
FROM:    Valentyna Golovnya at Main Astro Obs,Kyiv  <golov_v@ukr.net>

V. V. Golovnya, V. M. Andruk (Main Astro Obs., Kyiv)
report: 
   We have undertaken the review of the sky area of GRB 150220A 
(P.A. Evans, GCN Circ. 17501) on astronegatives, collected in Ukrainian
plate archive (1976-1996). All the plates with the possible object 
appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson
Expression 10000XL flatbed scanner and the images have been placed 
into Golosiiv Plate Archive database DBGPA with open access to them.

2 objects have been found on the plate GUA040C002183 (EPOCH=1993.2192).
Scanning and processing methods were described in [1-3]. The coordinates
and B magnitudes were obtained in the system of TYCHO-2 catalog: 

N of Obj.  MagTyc    RA(J2000)      Dec(J2000) 
1 (26646)  16.17   09h02m12.961s  -01d40â€™24.457â€
2 (26663)  15.96   09 02 13.504   -01 39 51.118 
        Rms RA=0.093â€, rms Dec=0.099â€, rms MagTyc=0.21

 The list of plates is given in the table:
yyyymmdd/TimeUT-- ---Plates---- Exp. â€“Mag --USNO-A2----
19830119/20:30:49 TAS040A000485 28.0 16.4 0825-06684950
19900323/19:14:27 GUA040C003371 12.5 15.6 0825-06686191
19930319/19:23:16 GUA040C002183 21.8 15.7 0825-06683708
Plates:
GUA040C â€“The plates archive identifier of DWA (D/F=400/2000,
         M=103â€/mm) of the Ukrainian NAS Main Astro obs.
         (Marsden's number - 83) the plate number [4].
TAS040A -the plates archive identifier of DAZ (D/F=400/3000,
         M=68.8â€/mm) of the Tashkent Astro obs.
         (Marsden's number - 186) the plate number [4].
Exp.  - Duration of the maximum exposure (minutes).
Mag - Limited Bmag, derived in the 13 minutes area around the 
position: RA(J2000): 09h 01m 51.6s, Dec(J2000): -01d 38â€™ 03â€.
USNO-A2 - Comparison star.
  The preview images of 3 areas together with the 13 min. of arc area
from Aladin can be found in
â€œhttp://gua.db.ukr-vo.org/img/grb/150220A/index.htmlâ€.
The images with full resolution are available via e-mail on demand.

References:
1. Andruk V.Ðœ., Butenko G.Z., Yatsenko A.I.: 2010, Kinematics and 
Physics of Celestial Bodies, 26/3, 75-81.
2. V.Golovnya, V.Andruk, A.Yatsenko: 2010, Journal of Physical 
Studies, 14, N2, 2902.
3. Yatsenko A.I., Andruk V.N., Golovnia V.V., Pakuliak L.K., Ivanov 
G.A.: 2011, Kinematics and Physics of Celestial Bodies, 27/3, 49-59.
4. L.Pakuliak: DBGPA V2.0, â€œhttp://gua.db.ukr-vo.orgâ€.


GRB_name: GRB150314A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17590
SUBJECT: GRB 150314A: Early RAPTOR Detection
DATE:    15/03/17 00:43:21 GMT
FROM:    James Wren at LANL  <jwren@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 observations of Swift
trigger 634795 (Hagen, et al., GCN 17573).  Our narrow-field instruments
located in Los Alamos, NM, USA, arrived on target at 04:55:20.83 UT, T+27.98
seconds after the BAT trigger time.  Our initial 5s exposure shows the
counterpart (Zheng, et al., GCN 17574) at an unfiltered magnitude of
13.11 +- 0.02.  The source fades steadily, reaching magnitude 15.87 +- 0.09
at T+180.38 s, in agreement with the KAIT lightcurve (Zheng, et al., GCN
17585).  We derive a power-law decay slope of -1.50 using 04:54:52.86 as
the BAT T0.  Our unfiltered magnitudes were calibrated to the USNO-B1 R-band
catalog.

The optical counterpart is not detected in any of our persistent wide-field
monitors during the gamma-ray emitting interval.  Typical 3-sigma unfiltered
limiting magnitudes during this period were V~9.8 based on comparison to the
Tycho-2 V-band catalog.


GRB_name: GRB150314A
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17591
SUBJECT: GRB 150314A: VLA observations
DATE:    15/03/17 00:52:29 GMT
FROM:    Tanmoy Laskar at Harvard U  <tanmoylaskar@gmail.com>

T. Laskar and E. Berger (Harvard) report on behalf of a larger
collaboration:

"We observed GRB 150314A (Hagen et al; GCN 17573) with the VLA beginning on
2015 March 16.1 UT (1.9 days after the burst). At a mean frequency of 5
GHz, we detect a radio source with a preliminary flux density of ~ 0.05 mJy
at

RA = 08:26:40.973 +/- 0.005
Dec = +63:50:03.29 +/- 0.08

consistent with the enhanced Swft/XRT position (Beardmore et al.; GCN
17575) and the optical position (Zheng et al.; GCN 17574). Follow-up
observations are planned."


GRB_name: GRB150317A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17592
SUBJECT: GRB 150317A: Swift detection of a burst
DATE:    15/03/17 05:17:11 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. H. Siegel (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),
A. Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:

At 04:22:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150317A (trigger=635148).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 138.935, +55.452, which is 
   RA(J2000)  =  09h 15m 45s
   Dec(J2000) = +55d 27' 08"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows three spikes 
spaced about 10 seconds apart, with a total duration of about 35 sec. 
The peak count rate was ~1700 counts/sec (15-350 keV), at ~0 sec 
after the trigger. 

The XRT began observing the field at 04:23:46.5 UT, 64.6 seconds after
the BAT trigger. 
In a 25 s SPER image XRT detects 10 photons at 
RA, DEC 138.9832, 55.4681 which is    
   RA(J2000)  =  09h 15m 55.98s
   Dec(J2000) = +55:28:05.23
with an uncertainty of 8.6 arcsec (radius, 90% containment). This position is 1.9 
arcmin away from the BAT onboard position, within the BAT error circle. 

We notice the presence of a bright star (R~11) at 11 arcseconds from the XRT 
position. At this time we cannot exclude that emission from the star 
may be affecting the XRT data. 

UVOT took a finding chart exposure of 250 seconds with the U filter
starting 126 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 none 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 M. H. Siegel (siegel AT swift.psu.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: GRB150317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17593
SUBJECT: GRB 150317A: NOT optical observations
DATE:    15/03/17 05:44:01 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Xu (DARK/NBI), D. Malesani (DARK/NBI), P. Blay (IAC, NOT), P. 
Jakobsson (Univ. Iceland), report on behalf of a larger collaboration:

We observed the field of the Swift GRB 150317A (Siegel et al., GCN 
17592) with the NOT equipped with the AlFOSC camera. A single 300-s 
R-band exposure was secured, starting at 04:48 UT (25 min after the GRB).

No new sources are detected within the X-ray position reported by Siegel 
et al. (GCN 17592), but we remark that in our image the bright glare 
from the nearby R=11 USNO star 1454-0197654 covers part of the XRT error 
circle. The limiting magnitude of our image is R ~ 21.5, but it is 
considerably shallower in the regions contaminated by the star PSF.

It cannot be excluded at the present time that the X-ray source detected 
by XRT is due to the USNO star. Visual inspection of the BAT error 
circle also does not reveal any new object compared to archival DSS and 
SDSS images, down to R = 21.5.


GRB_name: GRB150317A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17594
SUBJECT: GRB 150317A: Enhanced Swift-XRT position
DATE:    15/03/17 08:03:37 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Using 2091 s of XRT Photon Counting mode data and 2 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 = 138.98467, 55.46618 which is equivalent to:

RA  (J2000):  09h 15m 56.32s
Dec (J2000): +55d 27' 58.2"

with an uncertainty of 2.2 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: GRB150317A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17595
SUBJECT: GRB 150317A: RATIR Optical Afterglow Detection
DATE:    15/03/17 14:41:50 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
(ORAU/GSFC), 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 150317A (Siegel, et al., GCN 17592) 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 2015/03 17.18 to 2015/03 17.43 UTC (3 minutes
to 5.9 hours after the BAT trigger), obtaining a total of 3 hours exposure
in the r, i, and z bands.

We find an uncatalogued source within the Swift-XRT error circle (Evans et
al., GCN 17594).  In comparison with the SDSS DR9 and 2MASS, we obtain the
following detections and upper limit (3-sigma):

  r     20.5 +/- 0.1
  i     21.7 +/- 0.1
  z     > 20.8

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  This photometry is preliminary and
can be expected to improve with a more detailed analysis due to the
proximity of a bright star (e.g., Xu, et al., GCN 17593).

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


GRB_name: GRB150317A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17596
SUBJECT: GRB 150317A: Swift-BAT refined analysis
DATE:    15/03/17 20:52:03 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. H. Siegel (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-236 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150317A (trigger #635148)
(Siegel, et al., GCN Circ. 17592).  The BAT ground-calculated position is
RA, Dec = 138.995, 55.477 deg which is
    RA(J2000)  =  09h 15m 58.8s
    Dec(J2000) = +55d 28' 38.7"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows three separate peaks, each of duration ~5 
seconds, with maxima at T+0, T+12 and T+23 seconds. T90 (15-350 keV) is 23.29 +- 
0.85 sec (estimated error including systematics).

The time-averaged spectrum from T-0.44 to T+24.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.52 +- 0.16.  The fluence in the 15-150 keV band is 6.5 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.15 sec in the 15-150 keV band
is 1.2 +- 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/635148/BA/


GRB_name: GRB150317A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17597
SUBJECT: GRB 150317A: Swift-XRT refined Analysis
DATE:    15/03/17 21:12:25 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

A.P. Beardmore (U. Leicester), A. Amaral-Rogers (U. Leicester), M. de
Pasquale (INAF-IASFPA), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift-XRT
team:

We have analysed 15 ks of XRT data for GRB 150317A (Siegel et al. GCN
Circ. 17592), from 68 s to 42.4 ks after the  BAT trigger. The data
comprise 19 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. Using 5905 s of PC mode data and 7 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 =
138.98467, +55.46573 which is equivalent to:

RA (J2000): 09h 15m 56.32s
Dec(J2000): +55d 27' 56.6"

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=0.90 (+0.06, -0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+/-0.3). The
best-fitting absorption column is  2.9 (+0.6, -0.5) x 10^22 cm^-2, in
excess of the Galactic value of 3.0 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.9 x 10^-11 (2.0 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.9 (+0.6, -0.5) x 10^22 cm^-2
Galactic foreground: 3.0 x 10^20 cm^-2
Excess significance: 9.2 sigma
Photon index:      2.3 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
0.90, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x
10^-13 (5.3 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/00635148.

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


GRB_name: GRB150317A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17598
SUBJECT: GRB 150317A: Swift/UVOT Upper Limits
DATE:    15/03/18 03:49:56 GMT
FROM:    Margaret Chester at PSU  <chester@swift.psu.edu>

M. M. Chester (PSU) and M. H. Siegel (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150317A
126 s after the BAT trigger (Siegel et al., GCN Circ. 17592).
Due to the location of the counterpart (Evans and Goad GCN Circ. 17594, 
Butler et al. GCN Circ. 17595) in the wings of the nearby bright star 
(V~11.2), we cannot report a certain detection.  We therefore provide 
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, as follows:

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

u_FC       126          376          246      >19.6   
v          432         6158          334      >19.2   
b          381         6978          571      >20.4   
u          126         6773          739      >20.2   
w1         481         6568          335      >19.6   
m2         457         6363          255      >19.4   
w2         407         7037          384      >20.0   

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: GRB150318A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17599
SUBJECT: GRB 150318A: Swift detection of a burst
DATE:    15/03/18 07:20:45 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

C. Pagani (U Leicester), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), 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 07:04:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150318A (trigger=635289).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec  324.971, -61.477d which is 
   RA(J2000) = 21h 39m 53s
   Dec(J2000) = -61d 28' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 80 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 07:07:14.5 UT, 141.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 325.0056, -61.4559 which is equivalent to:
   RA(J2000)  = +21h 40m 1.34s
   Dec(J2000) = -61d 27' 21.2"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 96 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 164 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
0.04. 

Burst Advocate for this burst is C. Pagani (cp232 AT star.le.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: GRB150318A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17600
SUBJECT: GRB 150318A: Enhanced Swift-XRT position
DATE:    15/03/18 11:09:49 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 669 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150318A, 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 = 325.00597, -61.45674 which is equivalent
to:

RA (J2000): 21h 40m 1.43s
Dec (J2000): -61d 27' 24.3"

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: GRB150318A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17602
SUBJECT: GRB 150318A : GROND upper limits
DATE:    15/03/18 13:14:38 GMT
FROM:    Karla Varela at MPE  <kvarela@mpe.mpg.de>

P. Wiseman, K. Varela, M.Salvato and J. Greiner (all MPE Garching) report
on behalf of the GROND team:

We observed the field of GRB 150318A (SWIFT-635289; Pagani et al.,
GCN#17599) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008,PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile). Observations started on March 18rd, 2015, at 08:27UT,
83 minutes after the GRB trigger. They were performed at an average seeing
of 1.3" and at an average airmass of 2.0.

We do not detect a source inside the 1.9 arcsec error circle reported by
Evans et al. (GCN #17600). Based on a total exposure of 0.67 hours in
gr'i'z'and 0.73 hours in JHK, we measure the following preliminary upper
limits (AB magnitudes system):

g' > 24.9 mag,
r' > 24.8 mag,
i' > 24.2 mag,
z' > 23.9 mag,
J > 21.4 mag,
H > 20.9 mag, and
K > 18.9 mag.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V) = 0.03 mag in the
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB150318A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17603
SUBJECT: GRB 150318A: Swift/UVOT Upper Limits
DATE:    15/03/18 13:52:59 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and C. Pagani (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150318A
151 s after the BAT trigger (Pagani et al., GCN Circ. 17599).
No optical afterglow consistent with the XRT position (Evans et al. GCN 
Circ. 17600) 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           151          300          147         >20.8
u_FC               308          558          246         >19.8
white              151         5695          530         >21.4
v                  638         6106          432         >20.0
b                  736         6762          252         >20.4
u                  308         6721          659         >20.4
w1                 687         6516          413         >20.2
m2                4676         6311          393         >20.1
w2                4266         5901          393         >20.8

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: GRB150318A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17604
SUBJECT: GRB 150318A: Swift-BAT refined analysis
DATE:    15/03/18 15:48:56 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), C. Pagani (U. Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 150318A (trigger #635289)
(Pagani, et al., GCN Circ. 17599).  The BAT ground-calculated position is
RA, Dec = 324.990, -61.461 deg, which is
    RA(J2000)  =  21h 39m 57.6s
    Dec(J2000) = -61d 27' 41.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 44%.

The mask-weighted light curve shows two very broad peaks.  The first one runs
from about T-10 sec to T+50 sec, and the second, brighter peak starts at T+50 sec,
peaks at ~T+65 sec and decays to background by T+120 sec.
T90 (15-350 keV) is 83.88 +- 12.57 sec (estimated error including systematics).

The time-averaged spectrum from T-6.60 to T+98.58 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.00 +- 0.12.  The fluence in the 15-150 keV band is 2.5 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+66.62 sec in the 15-150 keV band
is 1.1 +- 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/635289/BA/


GRB_name: GRB150318A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17605
SUBJECT: GRB 150318A: Skynet PROMPT-CTIO Observations
DATE:    15/03/18 18:23:19 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. Aji, R. Beauchemin, T. Berger, A. Dow, A. Foster,
N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. Maples, J. Moore, M. Nysewander, C. Salemi,
L. Zbinden, and J. A. Crain report:

Skynet observed the Swift BAT/XRT localization of GRB 150318A (Pagani et al., GCN 17599, Swift
trigger=635289) with with one 24" telescope (PROMPT 8; I band) and four 16" telescopes 
(PROMPT 1,3,4,5; V,B,R,I bands) of the PROMPT array at CTIO, Chile. 
Starting at 2015-03-18 06:06:54 UT and continuing until 09:52 UT (t=2m-2.8h post-trigger), 
Skynet took a total of 376 exposures ranging from 10-160s. We stacked subsets of these images 
to maximize the S/N ratio, and detected no optical source in any band at the XRT position.  
Our 3-sigma limiting magnitudes are:

==============================================
tmid    scope   band    exposures   lim mag
----------------------------------------------
104m    PROMPT8  I      69 x 80s     >20.9
104m    PROMPT5  I      43 x 160s    >20.9
78m     PROMPT4  R      37 x 80s     >20.9
104m    PROMPT1  V      42 x 160s    >21.6
125m    PROMPT3  B      18 x 160s    >21.1

Limiting magnitudes are in the Vega System, calibrated to 3 APASS stars in the field.  Magnitudes
have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.03
(Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.


GRB_name: GRB150314A
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17606
SUBJECT: GRB 150314A: Further VLA observations
DATE:    15/03/18 19:12:54 GMT
FROM:    Tanmoy Laskar at Harvard U  <tanmoylaskar@gmail.com>

T. Laskar and E. Berger (Harvard) report:

"We observed GRB 150314A (Hagen et al; GCN 17573) with the VLA beginning on
2015 March 17.2 UT (3.0 days after the burst). No significant radio
emission is detected at the enhanced Swft/XRT position (Beardmore et al.;
GCN 17575) or the optical position (Zheng et al.; GCN 17574). We therefore
confirm the radio source reported in our previous observations (Laskar et
al.; GCN 17591) as the radio afterglow. No further follow-up observations
are planned."


GRB_name: GRB150318A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17608
SUBJECT: GRB 150318A: Swift-XRT refined Analysis
DATE:    15/03/18 22:20:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), A. Amaral-Rogers (U. Leicester), A. Maselli 
(INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.P.
Osborne (U. Leicester) and C. Pagani report on behalf of the Swift-XRT
team:

We have analysed 6.3 ks of XRT data for GRB 150318A (Pagani et al. GCN
Circ. 17599), from 130 s to 40.1 ks after the  BAT trigger. The data
comprise 191 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. 17600).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.25 (+0.23, -0.29). At T+187 s  the decay
steepens to an alpha of 5.30 (+/-0.18) before breaking again at T+628 s
to a final decay with index alpha=0.94 (+0.19, -0.21).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.46 (+/-0.06). The
best-fitting absorption column is  3.17 (+0.22, -0.21) x 10^21 cm^-2,
in excess of the Galactic value of 3.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 2.9 x 10^-11 (5.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      3.17 (+0.22, -0.21) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 21.9 sigma
Photon index:      2.46 (+/-0.06)

If the light curve continues to decay with a power-law decay index of
0.94, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x
10^-14 (8.7 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/00635289.

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


GRB_name: GRB150323A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17611
SUBJECT: GRB 150323A: Swift detection of a burst
DATE:    15/03/23 03:01:27 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC),
F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 02:49:14 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150323A (trigger=635887).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 128.191, +45.434 which is 
   RA(J2000) = 08h 32m 46s
   Dec(J2000) = +45d 26' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a small peak at the
time of the trigger, followed by a much larger peak at T+130 s,
for a total duration of at least 170 sec.  The peak count rate
was ~5600 counts/sec (15-350 keV), at ~130 sec after the trigger. 

The XRT began observing the field at 02:51:41.2 UT, 146.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 128.17951,
45.46355 which is equivalent to:
   RA(J2000)  = 08h 32m 43.08s
   Dec(J2000) = +45d 27' 48.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 110 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 consistent with the Galactic value of 3.05
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 0.1 s image was 3.25e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 156 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 A. Amaral-Rogers (aar14 AT le.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: GRB150323A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17612
SUBJECT: GRB 150323A: P60 Optical Afterglow Candidate
DATE:    15/03/23 03:51:38 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration:

We observed the location of the Swift GRB150323A (Amaral-Rogers et al., GCN 17611) with the robotic Palomar 60 inch telescope.  Observations began at 2:57 UT (~ 8 minutes after the Swift trigger) and were obtained in the Sloan r, i, and z filters.  In a stacked r-band image with a mid-point of 3:07 UT, we detect a source at the edge of the XRT error circle, with coordinates:

  RA: 08:32:42.83    Dec: +45:27:53.5   (J2000)

At this time, we measure an r-band magnitude of ~ 20.6 (photometric calibration performed with respect to nearby point sources from SDSS). Given the lack of a quiescent counterpart in SDSS at this location, we consider this likely to be the afterglow of GRB150323A.

Observations are ongoing.


GRB_name: GRB150323A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17613
SUBJECT: GRB 150323A: RATIR Optical Afterglow Observations
DATE:    15/03/23 04:09:49 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
(ORAU/GSFC), 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 150323A (Amaral-Rogers, et al., GCN 17611)
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 2015/03 23.12 to 2015/03 23.16 UTC
(9.6 to 58.8 minutes after the BAT trigger), obtaining a total of 42.6
minutes exposure in the r, i, and z bands.

For the source on the edge of the Swift-XRT error circle (Cenko et al., GCN
17612), in comparison with the SDSS DR9, we obtain the following
measurements and upper-limit (3-sigma):

  r = 21.16 +/- 0.11
  i = 20.39 +/- 0.05
  z > 19.30

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  We note that this source appears
to be fading during our observation.

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


GRB_name: GRB150314A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17614
SUBJECT: GRB 150314A: GMG observation limit
DATE:    15/03/23 05:39:31 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, B. Lun and J.-M. Bai (YNAO) report:


We observed the field of GRB 150314A (Hagen et al., GCN 17573) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatory. Observations began from UT 12:22:09.5 14th, March, 2015 (about 7.5 hours after the trigger). We did not detect any optical source at the XRT position down to a limit of R~21.0.   


GRB_name: GRB150323A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17615
SUBJECT: GRB 150323A: Enhanced Swift-XRT position
DATE:    15/03/23 06:29:57 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 1311 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 150323A, 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 = 128.17800, +45.46464 which is equivalent
to:

RA (J2000): 08h 32m 42.72s
Dec (J2000): +45d 27' 52.7"

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: GRB150323A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17616
SUBJECT: GRB 150323A: Keck redshift
DATE:    15/03/23 07:20:09 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

Using the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m 
telescope, we acquired a single 900s spectrum of the optical afterglow 
(Cenko et al., GCN 17612) of GRB 150323A (Amaral-Roger et al., GCN 
17611) beginning at 06:11 UT, at the end of evening twilight.

A number of absorption and emission lines are detected in the 1D 
spectrum, including e.g. Fe II (2344,2374,2383,2585,2599), Mg II 
(2796,2803), Mg I (2853), OII (3727), OIII (4959, 5007), and H-beta at a 
common redshift of z=0.593.

We acknowledge S. Kulkarni for the observing time.


GRB_name: GRB150323A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17617
SUBJECT: GRB150323A: Swift-UVOT detection of the afterglow
DATE:    15/03/23 11:40:56 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and Amaral-Rogers (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150323A
156 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 17611).
A weak optical afterglow consistent with the XRT position (Goad et al.,
GCN Circ. 17615) or the P60 position (GCN Circ. 17612) is be present
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           156          306          147         20.53+/-0.30
u_FC               314          564          246         >20.0
white             4066         5702         1635         20.96+/-0.33
v                 5912         6112          197         18.93+/-0.29
u                  314         5291          442         >20.7
u                 4991         5191          197         19.86+/-0.35
w1                4887         5086          197         >20.2
m2                4682         4881          197         >20.9
w2                4272         4472          197         >20.4

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: GRB150323A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17618
SUBJECT: GRB 150323A: Swift-XRT refined Analysis
DATE:    15/03/23 15:01:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester) and A. Amaral-Rogers
report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 150323A (Amaral-Rogers et
al. GCN Circ. 17611), from 136 s to 29.5 ks after the  BAT trigger. The
data comprise 169 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 Goad
et al. (GCN Circ. 17615).

The late-time light curve (from T0+4.1 ks) can be modelled with a
power-law decay with a decay index of alpha=0.72 (+0.19, -0.16).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.26 (+0.06, -0.05). The
best-fitting absorption column is  6.2 (+/-0.5) x 10^21 cm^-2, at a
redshift of 0.593, in addition to the Galactic value of 3.0 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 2.03 (+0.20, -0.19) and a best-fitting absorption column of 4.6
(+1.8, -1.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum  is 3.4 x 10^-11
(4.7 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.0 x 10^20 cm^-2
Intrinsic column:    4.6 (+1.8, -1.6) x 10^21 cm^-2 at z=0.593
Photon index:      2.03 (+0.20, -0.19)

If the light curve continues to decay with a power-law decay index of
0.72, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (5.9 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/00635887.

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


GRB_name: GRB150323B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17619
SUBJECT: GRB 150323B detected in ground analysis of Swift-BAT data
DATE:    15/03/23 15:47:19 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. R. Cummings (CPI) on behalf of the Swift-BAT science team

At 09:28:38, Swift-BAT triggered (635929) on GRB 150323B. Imaging attempts
were prematurely terminated by a preplanned slew.  A bright source
was detected in ground analysis at 260.447, +38.316, which is

RA (J2000)   17h 21m 47.3s
Dec (J2000)  38d 18' 59"

with an estimated 90% error radius of 1.5 arcmin.

The burst had multiple peaks with a T90 of about 60 seconds. We have
event data for only the first peak.

This is the same event as Fermi GBM 448795722.  A Swift TOO has been
requested.


GRB_name: GRB150323B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17620
SUBJECT: GRB 150323B: Swift ToO observations
DATE:    15/03/23 16:42:36 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 150323B. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020485

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150323C
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17621
SUBJECT: GRB 150323C: Swift detection of a burst
DATE:    15/03/23 17:15:23 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Amaral-Rogers (U Leicester), W. H. Baumgartner (GSFC/UMBC),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 17:05:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150323C (trigger=636005).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 192.613, +50.198 which is 
   RA(J2000) = 12h 50m 27s
   Dec(J2000) = +50d 11' 54"
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 40 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 17:08:11.3 UT, 169.8 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 192.6177, 50.1910 which is equivalent to:
   RA(J2000)  = +12h 50m 28.25s
   Dec(J2000) = +50d 11' 27.6"
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This
location is 27 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 178 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
0.01. 

Burst Advocate for this burst is A. Amaral-Rogers (aar14 AT le.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: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17622
SUBJECT: GRB 150323C: MASTER-net optical observation 
DATE:    15/03/23 17:22:58 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

V.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, Kourovka

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

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)

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory



MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was pointed to the  GRB150323C 42 sec after notice time 
and 88 sec after trigger time at 2015-03-23 17:09:39 UT in two 
polarizations. On our first (20s exposure)  set we haven't found optical 
transient  within SWIFT error-box (Amaral-Rogers et al. GCN17621).
The 5-sigma upper limit has been about 17.6 mag


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Ural was pointed to the  GRB150323C 35 after notice time and 79 
sec after trigger time at 2015-03-23 17:09:31 UT  in two polarizations. On 
our first (20s exposure)  set we haven't found optical transient  within 
SWIFT error-box (ra=12 50 28 dec=+50 11 25 r=0.001400).
The 5-sigma upper limit has been about 17.9 mag


The message may be cited.


GRB_name: GRB150323B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17623
SUBJECT: GRB 150323B: Fermi GBM observation
DATE:    15/03/23 17:24:20 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

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

"At 09:28:39.21 UT on 23 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150323B (trigger 448795722 / 150323395), 
which was also detected by the Swift (Cummings et al. 2015, GCN 17619).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 69 degrees.

The GBM light curve consists of multiple peaks 
with a duration (T90) of about 54 s (50-300 keV).
The time-averaged spectrum from T0-0.512 s to T0+60.929 s is
best fit by a Band function with Epeak = 99.14 (+4.50/-6.02) keV,
alpha = -0.89 (+0.07/-0.05), and beta = -2.04 (+0.03/-0.03). 

The event fluence (10-1000 keV) in this time interval is
(2.19 +/- 0.03)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+1.152  s in the 10-1000 keV band
is 8.2 +/- 0.3 ph/s/cm^2.

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


GRB_name: GRB150323C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17624
SUBJECT: GRB 150323C: Prompt enhanced Swift-XRT position
DATE:    15/03/23 17:48:13 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:

Using  promptly downlinked XRT event data for GRB 150323C, we find an
enhanced XRT position of the afterglow: RA, Dec: 192.6169, 50.1918
which is equivalent to:
   RA (J2000)  = 12 50 28.05
   Dec (J2000) = +50 11 30.4
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/636005.

Position enhancement is 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: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17625
SUBJECT: GRB 150323C: Nanshan optical afterglow detection
DATE:    15/03/23 18:10:39 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), H.-B. Niu, J.-Z. Liu, G.-X. Pu, A. Esamdin, L. Ma
(XAO) report:

We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621)
using the 1m telescope at Nanshan, Xinjiang, China. Observations were
carried out in R-band, starting at 17:19:50 UT on 2015-03-23, i.e.,
869 s after the burst.

A source, not present in SDSS and DSS, is well detected in individual
images at coordinates

RA(J2000)  = 12:50:27.92
Dec(J2000) = +50:11:28.75

with an uncertainty of ~ 1 arcsec, being consistent with the enhanced
Swift-XRT position (Evans, GCN 17624). We thus think it's the optical
afterglow of the burst, and it has m(R) = 21.3 +/- 0.2 at a median
time of 1344s post-burst, calibrated with the SDSS field.


GRB_name: GRB150323A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17626
SUBJECT: GRB 150323A: KAIT Optical Observations
DATE:    15/03/23 21:09:12 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150323A (Amaral-Rogers
et al., GCN 17611) starting at 03:23:43 UT, ~34 minutes after
the burst. Observations were performed with an automatic sequence
in the clear (roughly R), V, and I filters, and the exposure time was
20 s per image. The afterglow reported by Cenko & Perley (GCN 17612)
was not detected in any single image, but was marginally detected
in the co-add image of 20 clear band images. We estimated the
brightness is R~20.3 +/- 0.3 at a mean time of 71.2 minutes after
the burst.


GRB_name: GRB150323C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17627
SUBJECT: GRB150323C: Fermi GBM detection
DATE:    15/03/24 00:25:37 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

Matthew Stanbro (UAH) reports on behalf of the Fermi GBM Team:

"At 17:05:09.64 UT on 23 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150323C (trigger 448823112 / 150323712)
which was also detected by the Swift/BAT (Amaral-Rogers et al. 2015, GCN 17621)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 58 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 43 s (50-300 keV).
The time-averaged spectrum from T0-10.24 s to T0+30.72 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.15 +/- 0.16 and
the cutoff energy, parameterized as Epeak, is 107 +/- 18 keV.

The event fluence (10-1000 keV) in this time interval is
(2.50 +/- 0.19)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.22 s in the 8-1000 keV band
is 1.64 +/- 0.20 ph/s/cm^2.

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


GRB_name: GRB150323A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17628
SUBJECT: GRB 150323A, Swift-BAT refined analysis
DATE:    15/03/24 01:11:42 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), A. Amaral-Rogers (U Leicester), 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 (GSFC/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-235 to T+967 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150323A (trigger #635887)
(Amaral-Rogers, et al., GCN Circ. 17611).  The BAT ground-calculated position is
RA, Dec = 128.173, 45.442 deg which is
  RA(J2000)  =  08h 32m 41.52s
  Dec(J2000) =  +45d 26' 29.76"
with an uncertainty of  2.07 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.

The mask-weighted light curve shows a multi-peaked structure with two main
pulses. The first weaker pulse starts at ~ T0, peaks at ~ T+7 s, and ends at
~ T+25 s. The second brighter pulse starts at ~ T+125 s , peaks at ~ T+135 s,
and ends at ~ T+160 s. T90 (15-350 keV) is 149.6 +- 8.9 sec (estimated error
including systematics).

The time-averaged spectrum from T+2.6 to T+195.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.85 +- 0.07.  The fluence in the 15-150 keV band is 6.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+135.64 sec in the 15-150 keV band
is 5.4 +- 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/635887/BA/


GRB_name: GRB150323C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17629
SUBJECT: GRB 150323C: Xingming upper limit
DATE:    15/03/24 04:09:25 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), X. Gao (Urumqi No.1 Senior High School, Xinjiang),
and Z.-J. Xu (Nanjing Putian Telecommunications Co. Ltd., Jiangsu)
report:

We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621)
using the 0.35m robotic Xingming telescope located at Nanshan,
Xinjiang, China. Observations started at 17:08:06 UT on 2015-03-23,
i.e., 165 s after the burst, and a series of 40s, 60s, and 90s
unfiltered exposures were obtained.

No optical source is detected at the enhanced Swift-XRT position
(Evans, GCN 17624), down to a limiting magnitude of ~19.2 mag since
the starting of our observations.


GRB_name: GRB150323C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17630
SUBJECT: GRB 150323C: Swift-XRT refined Analysis
DATE:    15/03/24 05:15:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), J.A. Kennea (PSU), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), K.L. Page (U.
Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A.
Maselli  (INAF-IASFPA) and A. Amaral-Rogers report on behalf of the
Swift-XRT team:

We have analysed 6.1 ks of XRT data for GRB 150323C (Amaral-Rogers et
al. GCN Circ. 17621), from 160 s to 12.6 ks after the  BAT trigger. The
data comprise 312 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 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 = 192.6169, 50.1918 which
is equivalent to:

RA (J2000): 12 50 28.05
Dec(J2000): +50 11 30.4

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The late-time light curve (from T0+5.1 ks) can be modelled with a
power-law decay with a decay index of alpha=1.0 (+/-0.5).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.34 (+/-0.05). The
best-fitting absorption column is  1.55 (+0.13, -0.12) x 10^21 cm^-2,
in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.52 (+0.25, -0.23)
and a best-fitting absorption column of 6.5 (+4.5, -3.9) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 2.7 x 10^-11 (3.5 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.5 (+4.5, -3.9) x 10^20 cm^-2
Galactic foreground: 1.2 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index:      2.52 (+0.25, -0.23)

If the light curve continues to decay with a power-law decay index of
1.0, the count rate at T+24 hours will be 3.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.8 x
10^-14 (1.3 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/00636005.

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


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17631
SUBJECT: GRB 150323C :  Xinglong TNT optical observation
DATE:    15/03/24 05:34:21 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L. P. Xin,   X. F. Wang,  J. Y. Wei,  Y. L. Qiu,  J. S. Deng, 
J. Wang,  X. H. Han and C. Wu on behalf of EAFON report:
 
We began to observe GRB 150323C (Amaral-Rogers et al., GCN 17621) 
with Xinglong  0.8-m TNT telescope at 2015-03-23, 17:07:27(UT),
about 126 sec after the Swift trigger time. 
 
The new source within XRT circle  (Amaral-Rogers et al., GCN 17621 ) 
 reported by Xu et al., ( GCN 17625 )  was clearly detected  in our coadded images.  
Preliminary analysis shows that  the brightness of this optical transient 
in R band is rising  from 21.6 to 20.2 and then decaying,  
indicating that this source is the optical afterglow of the burst.  
All the magnitudes are calibrated by a nearby USNO B1.0 object 
( RA: 16:50:26  DEC: 50:11:48, R2=16.47mag ).
 
The message may be cited.


GRB_name: GRB150323C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17632
SUBJECT: GRB 150323C: RATIR Optical Afterglow Observations
DATE:    15/03/24 06:49:44 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Alan M. Watson (UNAM), Owen Littlejohns (ASU), 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
(ORAU/GSFC), Eleonora Troja (GSFC), 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 150323C (Amaral-Rogers, et al., GCN
17621) 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 2015/03 24.14 to 2015/03 24.27 UTC (10.20 to 13.42 hours
after the BAT trigger), obtaining a total of 2.49 hours exposure
in the r, i and z bands.

For a source within the Swift-XRT error circle (D'Elia, et al.,
GCN 17630), in comparison with the SDSS DR9, we obtain the
following detections and upper limit (3-sigma):

  r     23.00 +/- 0.15
  i     22.63 +/- 0.11
  z     > 20.61

These magnitudes are in the AB system and are not corrected for
Galactic extinction in the direction of the GRB. In comparison to
an earlier epoch of observations (Xin, et al., GCN 17631) we find
this magnitude to be consistent with a power-law decay with an
approximate temporal decay index alpha = 0.5.

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


GRB_name: GRB150323C
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17633
SUBJECT: GRB 150323C: Enhanced Swift-XRT position
DATE:    15/03/24 09:02:46 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 5836 s of XRT Photon Counting mode data and 7 UVOT
images for GRB 150323C, 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 = 192.61686, +50.19121 which is equivalent
to:

RA (J2000): 12h 50m 28.05s
Dec (J2000): +50d 11' 28.4"

with an uncertainty of 1.6 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: GRB150323B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17634
SUBJECT: GRB 150323B: Swift-XRT observations
DATE:    15/03/24 11:07:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA),
D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.
Leicester) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 150323B (Cummings et al. GCN Circ. 17619),
collecting 4.6 ks of Photon Counting (PC) mode data between T0+40.4 ks
and T0+63.2 ks. 

Two uncatalogued X-ray sources have been detected inside or close to
the Swift/BAT error region, however none of them is above the RASS
limit or shows definitive signs of fading. Therefore, at the present
time we cannot identify which, if any, is the afterglow. Details of
these sources are given below:

Source 1:
  RA (J2000):  260.4534  =  17:21:48.83
  Dec (J2000): +38.3179  =  +38:19:04.6
  Error: 4.3 arcsec (radius, 90% conf.)
  Count-rate: 0.0103 +/- 0.0018 ct s^-1
  Flux: (4.62 +/- 0.80)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000):  260.4598  =  17:21:50.35
  Dec (J2000): +38.2829  =  +38:16:58.5
  Error: 6.6 arcsec (radius, 90% conf.)
  Count-rate: (2.3 +/- 1.0)e-3 ct s^-1
  Flux: (9.2 +/- 4.1)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020485.

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


GRB_name: GRB150323C
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17635
SUBJECT: GRB 150323C: Swift/UVOT Upper Limits
DATE:    15/03/24 12:55:50 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Amaral-Rogers (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150323C
179 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 17621).
No optical afterglow consistent with the optical position
(Xu et al. GCN Circ. 17625) 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           179          328          147         >21.5
u_FC               337          587          246         >20.7
white              179        11759         1513         >22.4
v                  669        12698          555         >21.0
b                  594         7661          444         >21.1
u                  337         7541          717         >21.0
w1                 718         7337          432         >21.2
m2                5494         7131          393         >20.6
w2                5084        12665         1279         >22.1

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: GRB150323C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17637
SUBJECT: GRB 150323C, Swift-BAT refined analysis
DATE:    15/03/24 20:28:56 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), Amaral-Rogers (U Leicester), 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 (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-274 to T+800 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150323C (trigger #636005)
(Amaral-Rogers, et al., GCN Circ. 17621).  The BAT ground-calculated position is
RA, Dec = 192.625, 50.165 deg which is
  RA(J2000)  =  12h 50m 30.1s
  Dec(J2000) = +50d 09' 55.3"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows several weak overlapping pulses. The main
burst structure starts at ~ T-20 s and ends at ~T+20 s, followed by another weaker
pulse lasting till ~ T+160 s. T90 (15-350 keV) is 159.4 +- 54.0 sec (estimated error
including systematics).

The time-averaged spectrum from T-22.9 to T+166.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.09 +- 0.32.  The fluence in the 15-150 keV band is 1.3 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+5.98 sec in the 15-150 keV band
is 1.1 +- 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/636005/BA/


GRB_name: GRB150323B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17638
SUBJECT: GRB 150323B :  Xinglong TNT upper limit
DATE:    15/03/25 07:03:31 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

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


We began to observe GRB 150323B (Cumming., GCN 17619;  Kienlin., GCN 17623) 
with Xinglong  0.8-m TNT telescope at 2015-03-23, 18:19:24(UT),
about 8.85 hour after the Swift trigger time. 

 
No any new source was detected in our 10*300sec coadded image 
within the errorbox of BAT (Cumming.,  GCN 17619),
and the errorbox of two uncatalogured X-ray sources (Avanzo et al., 17632)
down to the 3 sigma limit of 21.8 mag in R-band, calibrated by USNO B1.0 R2 mag,
at the mean time of 9.28 hours after the burst. 


We noted that there was a source in USNO B1.0 catalog 
( 17:21:50.446  +38:17:00.13  R2=20.5 mag ),
which was located in the errorbox of the Source 2 (Avanzo et al., 17632),  
but the variation of its brightness was not decided.


The message may be cited.


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17639
SUBJECT: GRB 150323C:  Mondy optical observations
DATE:    15/03/25 13:29:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev 
(ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the GRB 150323C (Amaral-Rogers  et al., GCN 
17621) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 
Mar., 23 (UT) 11:42:02. We obtained several images in R-filter of 120 s 
exposure. Within  enhanced Swift-XRT error circle (Osborne et al., GCN 
17633)  we clearly detect optical  afterglow (Xu et al. GCN 17625, Xin 
et al. GCN 17631; Watson et al. GCN 17632) in a combined image. 
Preliminary photometry of the afterglow is following

Date       UT start   t-T0     Filter   Exp.    OT    Err.
                       (mid, days)       (s)

2015-03-24 15:14:09   0.95405  R        44*120  22.4 0.3


Photometry is based on SDSS DR9 stars:

SDSS9_id            R(Lupton)
J125023.08+501048.2 16.84
J125032.04+501021.5 18.37
J125016.28+501035.8 18.22


GRB_name: GRB150323A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17640
SUBJECT: Konus-Wind observation of GRB 150323A
DATE:    15/03/25 14:47:56 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long-duration GRB 150323A (Swift-BAT trigger #635887:
Amaral-Rogers et al., GCN 17611; Markwardt et al., GCN 17628)
triggered Konus-Wind at T0=10282.369 s UT (02:51:22.369).

The burst light curve shows a weak precursor at ~T0-135 s,
which triggered BAT, followed by the main episode which
started at ~T0-3 s and has a duration of ~38 s.
The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.1(-0.1,+0.1)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.152 s,
of 1.2(-0.6,+0.6)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.22(-0.28,+0.32),
and Ep = 95(-13,+16) keV (chi2 = 70/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.80 (chi2 = 70/97 dof).

The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 3 MeV range
by the power law with exponential cutoff model
with  alpha = -1.21(-0.26,+0.30),
and Ep = 121(-18,+25) keV (chi2 = 71/68 dof).
Fitting by a GRB (Band) model yields almost the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.43 (chi2 = 71/67 dof).

Assuming the redshift z=0.593 (Perley and Cenko, GCN 17616)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release 1.0(-0.1,+0.1)x10^52 erg,
the peak luminosity L_iso is 1.7(-0.8,+0.8)x10^51 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is 151(-21,+25) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150323_T10282/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150323B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17641
SUBJECT: Konus-Wind observation of GRB 150323B
DATE:    15/03/25 16:39:15 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long-duration GRB 150323B
(Swift-BAT trigger #635929: Cummings, GCN 17619;
Fermi-GBM observation: von Kienlin, GCN 17623)
triggered Konus-Wind at T0=34121.196 s UT (09:28:41.196).

The burst light curve shows several bright peaks during first ~60 s 
after the trigger.
In the instrument's soft energy channel, the flaring can be traced up to 
~T0+150 s.

As observed by Konus-Wind, the burst
had a fluence of 2.0(-0.1,+0.2)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+22.656 s,
of 1.4(-0.6,+0.6)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+65.792 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.53(-0.10,+0.11),
and Ep = 109(-12,+15) keV (chi2 = 109/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.90 (chi2 = 109/97 dof).

The spectrum near the peak count rate
(measured from T0+16.640 to T0+24.832 s)
is best fit in the 20 keV - 1 MeV range
by the power law with exponential cutoff model
with  alpha = -1.15(-0.25,+0.29),
and Ep = 215(-51,+108) keV (chi2 = 35/59 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -1.97 (chi2 = 35/58 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150323_T34121/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150323A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17642
SUBJECT: Subject: GRB 150323A;  Konkoly optical observations
DATE:    15/03/25 20:36:46 GMT
FROM:    Janos Kelemen at Konkoly Obs/Hungary  <kelemen@konkoly.hu>

J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program
at the Konkoly Observatory.


Starting on the evening 23/03/2015 18:30 UT we observed the field GRB 150323A
(A. Amaral-Rogers et al. GCN 17611, and M.R. Goad et al. GCN 17615).
We can confirm the presence of the supposed afterglow reported by
S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) (GCN 17612) at the position

RA: 08:32:42.69 DEC: 45:27:53.6

Our position and the P60 position are the same within 1 pixel.

On the coadded images (total exposure time = 2400 sec) we measured an R -band 
magnitude of m(R) = 20.3 +/- 0.14 with respect to nearby USNO-B1.0 stars.



time from GRB.    exp    filter        Mag.      
------------------------------------------------
 56136 s.       2400 s     R       20.3 +/-0.14
------------------------------------------------ 


GRB_name: GRB150323B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17643
SUBJECT: GRB 150323B;  Konkoly optical observations
DATE:    15/03/25 20:49:43 GMT
FROM:    Janos Kelemen at Konkoly Obs/Hungary  <kelemen@konkoly.hu>

J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program
at the Konkoly Observatory.

Starting on the night 24/03/2015 02:48 UT we observed the field GRB 150323B
(J. R. Cummings GCN 17619 ). We imaged the X-ray positions published by P.
D'Avanzo et al. GCN 17634.
 On the coadded R band images (total exposure = 1500 sec) we found marginal
optical sources on the positions coincide with soure 1 and source 2.

Source 1  /GCN 17634/         our work        R mag.(Based on USNO-B1.0 stars)
--------------------------------------------------------
        RA: 17:21:48.83    RA: 17:21:48.62       20.8 +/-0.14
       DEC: 38:19:04.6    DEC: 38:19:08.8


Source 2  /GCN 17634/         our work        R mag.(Based on USNO-B1.0 stars)
--------------------------------------------------------
        RA: 17:21:50.35    RA: 17:21:50.47       19.9 +/-0.14
       DEC: 38:16:58.5    DEC: 38:16:59.7

Due to the bad weather variability was not confirmed.


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17644
SUBJECT: Subject: GRB 150323C;  Konkoly optical observations
DATE:    15/03/25 21:02:06 GMT
FROM:    Janos Kelemen at Konkoly Obs/Hungary  <kelemen@konkoly.hu>

J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program
at the Konkoly Observatory.

Starting on the night 23/03/2015 we observed the field GRB 150323C
(A. Amaral-Rogers et al. GCN 17621 ). On the position reported by D. Xu et al.
(GCN 17625) according our coadded R images we confirmed the presence of a 
marginal optical source in R band.


Position from D. Xu                    our work
---------------------------------------------------------------

RA(J2000)  = 12:50:27.92            RA: 12:50:28.02
Dec(J2000) = +50:11:28.75          DEC: 50:11:28.3


Photometric results: (Based on nearby USNO-B1.0 stars)

time from GRB.    exp    filter     Mag.      
------------------------------------------------
 10653 s.       1800 s     R       21.7 +/-0.18
------------------------------------------------ 


GRB_name: GRB150220A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17645
SUBJECT: GRB 150220A: Optical observations at Kyiv comet station
DATE:    15/03/26 13:05:37 GMT
FROM:    Valentyna Golovnya at Main Astro Obs,Kyiv  <golov_v@ukr.net>

Ya. Romanyuk (Main Astro Obs., Kyiv), A. Baransky (Astr. Obs. of Kyiv
University), I. Kulyk, V. Golovnya, V. Andruk (Main Astro Obs., Kyiv)
report:

We observed the field of GRB 150220A (P.A. Evans, GCN Circ. 17501) with
0.7-m f/4 reflector of Kyiv comet station (Marsden's number â€“ 585).
The telescope is equipped with CCD, 1027ï‚´1056 pixels with a scale of
0.95"/px. We obtained 21ï‚´60sec images in R-filter on Mar., 10, 2015,
from (UTC) 19:08:15 to 19:44:09. Purpose of our observations was not to
search for the afterglow candidate. We would like to find two objects
referred to in (V. V. Golovnya, V. M. Andruk, GCN 17589), which was 
found on the old archive photographic plates in close vicinity of the
position of source '1SXPS J090208.3-014021':

RA,Dec(J2000)= 09h02m12.961s  -01d40'24.457"
        and    09 02 13.504   -01 39 51.118
The preview of archive photographic plates can be found at
'http://gua.db.ukr-vo.org/img/grb/150220A/index.html'    

The CCD images were processed with the standard technique and co-added
together to create a frame with higher signal/noise ratio. We did not 
find above mentioned objects on the CCD, but we confirmed some of the
positions reported early by P.A. Evans (GCN 17501). The following table
gives the positions listed by Evans, as well as the positions some 
of the objects calculated from the CCD.

Position from P. A. Evans, GCN 17501          our work
RA(J2000)          Dec(J2000)             RA(J2000)      Dec(J2000)
1) 09h 01m 31.65s -01Â° 39' 07.6" -------- outside our field
2) 09h 01m 30.74s -01Â° 38' 27.0" -------- outside our field
3) 09h 02m 08.55s -01Â° 36' 59.1" -------- 09h 02m 08.1s -01Â° 36' 35"
4) 09h 02m 08.90s -01Â° 40' 20.1" -------- extremely faint 
5) 09h 01m 28.27s -01Â° 39' 06.3" -------- outside our field
6) 09h 02m 25.29s -01Â° 41' 14.9" -------- 09h 02m 25.3s -01Â° 41' 15"
7) 09h 01m 46.37s -01Â° 38' 13.9" -------- 09h 01m 46.4s -01Â° 38' 14"


GRB_name: GRB150323C
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17646
SUBJECT: GRB 150323C: MITSuME Akeno Optical observation
DATE:    15/03/26 14:10:07 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

 T.Fujiwara, Y. Saito, T. Yoshii, Y. Tachibana, H. Ohuchi, 
Y. Yano, S.Kurita, Y. Ono, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 150323C (Amaral-Rogers et al. GCN Circular #17621) 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 at 2015-03-23 17:06:46 UT (85 sec after the burst).
We detected the previously reported optical afterglow (Xu et al. GCN Circular #17625) in the Rc band.

The measured magnitudes are listed below.

T0+[sec]  MID-UT  T-EXP[sec]    g'                Rc             Ic
----------------------------------------------------------------------
85   17:09:24  270     > 19.9  > 19.6  > 18.5
1069   17:34:06  1200    > 20.9  20.3 $B!^(B 0.5  > 19.5
6681   19:18:53  2400    > 20.4  > 20.4  > 19.4
----------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB150323A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17647
SUBJECT: GRB 150323A: AAO optical observations
DATE:    15/03/26 18:41:23 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO),   A. 
Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the Swift GRB 150323A (Amaral-Rogers et al., GCN 
17611)  with AS-32 (0.7m) telescope of Abastumani Observatory starting on 
Mar. 23 (UT) 22:47:06.  Within the enhanced XRT position (Goad et al., GCN 
17615) we do not detect any object. An upper limit is following

Date          UT start     t-T0        Filter    Exp.      UL(3 sigma)
                          (mid, days)                (s)

2015-03-23 22:47:06    0.85076  None    15*180   21.2

The photometry is based on nearby USNO-B1.0 stars. 


GRB_name: GRB150323C
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17648
SUBJECT: GRB 150323C: Nishi-Harima NIR Observations
DATE:    15/03/26 19:33:31 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

S. Honda. J. Takahashi, Y. Takagi, K. Morihana, Y. Itoh
(Univ. of Hyogo), and Y. Saito (Tokyo Tech)
report on behalf of Nayuta team and OISTER collaboration:

We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621)
with Nishiharima Infrared Camera (NIC) attached to the Nayuta 2-m
telescope at the Nishi-Harima Astronomical Observatory.

The observations were started at 17:30 UT on 2015-03-23.
We detected the near-infrared afterglow in J, H and Ks bands.

Photometric results of our observations are shown below.
We used 2MASS 12502614+5011480, 12502605+5011289, 12503202+5010217,
and 12503649+5012012 as reference stars for photometry.

# MID-UT  Tmid-T0 T-EXP  J_mag           H_mag               Ks_mag
--------------------------------------------------------------------------------
17:33:16    28   1200   18.22 +/- 0.10   17.25 +/- 0.10   16.44 +/- 0.13
17:59:27    54   1200   18.68 +/- 0.11   17.59 +/- 0.11   16.94 +/- 0.14
18:25:32    80   1200   19.40 +/- 0.20   17.77 +/- 0.13   17.23 +/- 0.14
---------------------------------------------------------------------------------
Tmid-T0: Elapsed time after the burst (minutes)
T-EXP: Total Exposure time (seconds)


GRB_name: GRB150323B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17649
SUBJECT: GRB 150323B: Khureltogot optical observations
DATE:    15/03/27 19:01:34 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of 
Astronomy and Geophysics MAS),  A. Volnova (IKI), I.Molotov (KIAM), A. 
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of GRB 150323B  (Cummings  et al., GCN 17619) with 
ORI-40 telescope of Khureltogot observatory  starting on   Mar., 23 (UT) 
16:06:11. We obtained 60 unfiltered images of 60 s exposure. Following 
detection of XRT sources (D'Avanzo et al., GCN 17634) we do not detect 
any source within XRT error circle of the source #1 up to a limiting 
magnitude 21.2. In particular we do detect the optical source found by 
Kelemen et al. (GCN 17643).  At the position of XRT source #2 we found 
optical source which coincides with USNO star mentioned by Xin et al. 
(GCN 17638) and the star of SDSS DR9 catalog J172150.45+381700.1.

Photometry of the sources is following

Source#  Date       UT start  t-T0    Filter  Exp.   mag.    UL(3sigma)
                              (mid, days)      (s)

1       2015-03-23  16:06:11  0.29859  none   60*60  n/d          21.2
2       2015-03-23  16:06:11  0.29859  none   60*60  20.7+/-0.25  21.2

The photometry is based on R magnitudes of nearby SDSS DR9 stars

SDSS9_id               R(Lupton)
J172146.77+381659.6    15.65
J172126.47+382201.1    18.14
J172127.98+382239.0    15.39


GRB_name: GRB150317A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17650
SUBJECT: GRB 150317A: likely host galaxy detection
DATE:    15/03/28 03:20:50 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), Nial R. Tanvir (Univ. Leicester), Zach Cano 
(Univ. Iceland), Pall Jakobsson (Univ. Iceland), and Tapio Pursimo (NOT) 
report on behalf of a larger collaboration:

We observed the field of GRB 150317A (Siegel et al., GCN 17592) using 
the Nordic Optical Telescope (NOT) located in La Palma. The mean time of 
the observation was March 23.95 UT, 6.77 days after the GRB. A 30 min 
exposure was collected using the SDSS i filter.

Inside the XRT error circle (Evans & Goad, GCN 17594), we detect a 
single source with i = 22.75 +- 0.25 AB (calibrated against nearby SDSS 
stars). The large error is mostly due to the bright, variable background 
from a nearby star. At the same position, an object with a consistent 
magnitude is also marginally visible in the archival SDSS data. Assuming 
that this object is coincident with the one detected by RATIR (Butler et 
al., GCN 17595), we thus suggest that this is the host galaxy of GRB 
150317A. Its coordinates are (J2000):

RA = 09:15:56.31
Dec = +55:27:58.0

with an uncertainty of 0.5". Such a bright galaxy may allow spectroscopy 
from an 8-m class telescope.


GRB_name: GRB150120B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17651
SUBJECT: GRB 150120B: GMG observation
DATE:    15/03/29 08:21:35 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, J. Zhang, and J.-M. Bai (YNAO) report:


We observed the field of GRB 150120B (D'Elia et al., GCN 17314) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station 
of Yunnan Observatory. Observations began from UT 13:42:43.5 20th, Jan., 2015 (about 6.3 hours after the trigger). 
We clearly detected the optical counterpart with brightness of R=22.1+/-0.1 mag.


J. Mao apologizes for this very late GCN circular submission.


GRB_name: GRB141225A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17652
SUBJECT: GRB 141225A: GMG observation limit
DATE:    15/03/29 09:33:06 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, Y. X. Xin and J.-M. Bai (YNAO) report:


We observed the field of GRB 141225A (D'Avanzo et al., GCN 17229) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG)
station of Yunnan Observatory. Observations began from UT 15:38:35.4 26th, Dec., 2014 (about 16.6 hours after the trigger). 
We did not detect the optical counterpart down to a limit of r'~24.3. 


J. Mao apologizes for this very later GCN circular submission.


GRB_name: GRB141220A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17653
SUBJECT: GRB 141220A: GMG observation limit
DATE:    15/03/29 11:09:44 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, B. Lun and J.-M. Bai (YNAO) report:


We observed the field of GRB 141220A (Cummings et al., GCN 17196) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) 
station of Yunnan Observatory. Observations began from UT 22:28:38.1 20, Dec., 2014 (about 18.4 hours after the trigger). 
We did not detect the optical counterpart down to a limit of r'~21.0. 


We thank Dr. A., de Ugarte Postigo for his kind suggestion and disucssion.  J. Mao apologizes for this very later GCN circular submission.


GRB_name: GRB141212A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17654
SUBJECT: GRB 141212A: GMG observation limit
DATE:    15/03/29 12:01:02 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, B. Lun and J.-M. Bai (YNAO) report:


We observed the field of GRB 141212A (Ukwatta et al., GCN 17158) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) 
station of Yunnan Observatory. Observations began from UT 12:58:57.9 12th, Dec., 2014 (about 45 mins after the trigger). 
We did not detect any optical source at XRT position down to a limit of R~22.0. In our single image, it is nearly impossible to
distinguish the sources clearly identified by Malesani et al. GCN 17170.   


We thank Dr. D., Malesani for his kind suggestion and discussion.  J. Mao apologizes for this very later GCN circular submission.


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17655
SUBJECT: GRB 150323C: possible host galaxy detection
DATE:    15/03/29 20:03:27 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), Dong Xu (DARK/NBI), Pall Jakobsson (Univ. 
Iceland) and Jussi Harmanen (NOT and Univ. Turku) report on behalf of 
a larger collaboration:

We observed the field of GRB 150323C (Amaral-Rogers et al., GCN 17621; 
Stanbro, GCN 17627) using the Nordic Optical Telescope (NOT) located in 
La Palma. The mean time of the observation was March 28.21 UT, that is 
4.49 days after the GRB. A 20 min exposure was collected using the SDSS 
r filter.

Close to the position of the optical afterglow (Xu et al., GCN 17625; 
Watson et al., GCN 17632), we detect an object with r = 23.6 +- 0.2 AB 
(calibrated against nearby SDSS stars). This source is also marginally 
detected in the archival SDSS images with a comparable (though 
uncertain) brightness, and therefore an underlying galaxy must be 
contributing a significant fraction of the light.

We note a small, but significant offset between the afterglow and the 
galaxy positions. By registering astrometrically the afterglow image by 
Xu et al. (GCN 17625) with the new NOT data, we find an offset of 
approximately 0.65". Such an offset is not unprecedented, so that the 
SDSS/NOT object is still a viable host galaxy candidate for GRB 150323C.

[GCN OPS NOTE(30mar15):  Per author's request, JH's affiliation was changed.]


GRB_name: GRB141121A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17656
SUBJECT: GRB 141121A: GMG observation
DATE:    15/03/30 06:23:44 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, Y. X. Xin, and J.-M. Bai (YNAO) report:


We observed the field of GRB 141121A (Lien et al., GCN 17075) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station 
of Yunnan Observatory. We obtain the following results of optical counterpart:


Date begin UT r' begin UT i'
Nov. 21, 2014 17:00:04 20.45+/-0.04 17:41:21 19.90+/-0.03
Nov. 22, 2014 17:57:44 22.46+/-0.09 18:38:40 21.89+/-0.08
Nov. 25, 2014 17:16:11 21.32+/-0.05 17:36:44 20.99+/-0.04
Nov. 27, 2014 18:28:57 22.60+/-0.08 18:49:23 21.99+/-0.05


Due to the poor seeing, we could not distinguish between the afterglow and the possible host galaxy.


J. Mao apologizes for this very late GCN circular submission.


GRB_name: GRB150323B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17657
SUBJECT: GRB 150323B: Swift-XRT afterglow detection
DATE:    15/03/30 14:10:10 GMT
FROM:    Alex Amaral-Rogers at U.of Leicester  <aar14@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA),
D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.
Leicester) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Swift/BAT-detected burst GRB 150323B (Cummings et al. GCN Circ. 17619).
The observations now extend from T0+40.4 ks to T0+483.5 ks. 

Of the sources reported by D'Avanzo et al. (GCN Circ. 17634), "Source
1" is fading with 3-sigma significance, and is therefore likely the GRB
afterglow.  The position of this source is RA, Dec=260.4534, +38.3179
which is equivalent to:

RA (J2000): 17:21:48.83
Dec(J2000): +38:19:04.6

with an uncertainty of 4.3 arcsec (radius, 90% confidence).  This
position is 18 arcsec from the Swift/BAT position.  The source is
fading with alpha >0.3.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00020485/index_1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020485.

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


GRB_name: GRB150330A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17658
SUBJECT: GRB 150330A: Fermi GBM detection
DATE:    15/03/31 05:15:27 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

Matthew Stanbro (UAH) reports on behalf of the Fermi GBM Team:

"At 19:52:21.27 UT on 30 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150330A (trigger 449437944 / 150330828).
The trigger resulted in an Autonomous Repoint Request (ARR) that was
accepted and the spacecraft slewed to the GBM in-flight location.

The on-ground calculated location, using the GBM trigger
data, is RA = 329.26, DEC = 49.97, with an uncertainty
of 1.00 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 80 degrees.

The GBM light curve shows/consists of two main episodes
with a combined duration (T90) of about 153 s (50-300 keV).
The time-averaged spectrum from T0+0.00 s to T0+151.68 s is
best fit by a Band function with Epeak = 284 +/- 5 keV,
alpha = -0.91 +/- 0.01, and beta = -2.15 +/- 0.02

The event fluence (10-1000 keV) in this time interval is
(1.28 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+130.8 s in the 10-1000 keV band
is 59.26 +/- 0.51 ph/s/cm^2.

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

-- 
Matthew C. Stanbro
Fermi GBM Graduate Research Assistant
University of Alabama in Huntsville


GRB_name: GRB150330A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17659
SUBJECT: IPN Triangulation of GRB 150330A (long/very intense)
DATE:    15/04/01 21:50:06 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

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

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

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT 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

G. Di Cocco, F. Fuschino, M. Galli, C. Labanti, and M. Marisaldi, on
behalf of the AGILE MCAL team, report:

The long-duration, very intense GRB 150330A has been detected by Fermi 
(GBM: Stanbro, GCN Circ 17658), Konus-Wind, MESSENGER (GRNS), INTEGRAL 
(SPI-ACS), Swift (BAT) and AGILE (MCAL), so far, at about 71541 s UT 
(19:52:21). 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:
   331.028 (22h 04m 07s) +52.297 (+52d 17' 48")
  Corners:
   327.825 (21h 51m 18s) +50.740 (+50d 44' 25")
   328.325 (21h 53m 18s) +51.170 (+51d 10' 12")
   334.589 (22h 18m 21s) +53.730 (+53d 43' 47")
   333.942 (22h 15m 46s) +53.336 (+53d 20' 10")
  ---------------------------------------------
The error box area is 2388 sq. arcmin, and its maximum
dimension is 5.1 deg (the minimum one is 8.6 arcmin).
The Sun distance was 57 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB150330_T71538/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming 
GCN Circular.


GRB_name: GRB150330A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17660
SUBJECT: Konus-Wind observation of GRB 150330A
DATE:    15/04/02 08:02:27 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long-duration, very bright GRB 150330A
(Fermi-GBM detection: Stanbro, GCN 17568
IPN triangulation: Hurley et al., GCN 17659)
triggered Konus-Wind at T0=71538.572 s UT (19:52:18.572).

The light curve starts with a double-peaked pulse
lasting from ~T0 to ~T0+10 s followed by a bright
multi-peaked structure from ~T0+97 s to ~T0+195 s.
The emission is seen up to ~15 MeV.

As observed by Konus-Wind, the burst had a fluence
of 2.1(-0.2,+0.2)x10^-4 erg/cm2, and a 64-ms peak flux,
measured from T0+130.560 s, of 3.4(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+194.560 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 = -0.96 (-0.07,+0.07),
the high energy photon index beta = -2.16 (-0.11,+0.08),
the peak energy Ep = 222 (-20,+21) keV,
chi2 = 85/97 dof.

The spectrum near the peak count rate (measured from T0+129.536
to T0+131.072 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 = -0.72 (-0.09,+0.09),
the high energy photon index beta = -1.98 (-0.08,+0.06),
the peak energy Ep = 341 (-44,+52) keV,
chi2 = 107/96 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150330_T71538/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150402A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17661
SUBJECT: GRB 150402A detected in ground analysis of Swift-BAT data
DATE:    15/04/02 23:32:01 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. R. Cummings (CPI) and D. M. Palmer (LANL) on behalf of the Swift-BAT science team:

At 00:37:46 Swift-BAT triggered on GRB 150402A (trigger# 636865). Image
attempts were prematurely terminated by a preplanned slew.  A significant
source was found in ground analysis at RA, Dec 173.658, +40.992, which is

RA (J2000)  11h 34m 37.9s
Dec (J2000) 40d 59' 33"

with an estimated uncertainty radius of 2.5 arcmin (90% containment).

The lightcurve shows two symmetrical peaks, each about 5 seconds long, the
second harder and brighter.  The counting rate in BAT of the brighter peak
was about 1500 counts/sec.  T90 was about 14 +- 2 seconds.

A Swift TOO has been requested in order to locate the afterglow.


GRB_name: GRB150402A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17662
SUBJECT: GRB 150402A: Swift ToO observations
DATE:    15/04/03 06:21:08 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 150402A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020486

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150402A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17663
SUBJECT: GRB 150402A: RATIR Optical Observations
DATE:    15/04/03 19:03:37 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Owen Littlejohns (ASU), 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 (ORAU/GSFC), Eleonora
Troja (GSFC), 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 150402A (Cummings, et al., GCN 17661)
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
2015/04 3.02 to 2015/04 10.92 UTC (26.39 to 34.29 hours after the
BAT trigger), obtaining a total of 3.16 hours exposure in the r
and i bands.

Currently, there is only one source detected by the Swift/XRT
within the Swift/BAT error circle (Evans, GCN 17662).

  RA(J2000)  =  11h 34m 34.0s
  Dec(J2000) = +40d 58' 37.8"

This source has an error circle of 6.2 arcseconds. We detect
no uncatalogued transient inside the error circle for this source.
In comparison with the SDSS DR9, we obtain the following upper
limits (3-sigma):

  r     > 22.75
  i     > 22.68

These magnitudes are in the AB system and 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: GRB150402A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17664
SUBJECT: GRB 150402A: results of Swift observations
DATE:    15/04/03 21:38:20 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

H. A. Krimm (CRESST/GSFC/USRA), M. De Pasquale (INAF-IASFPA),
N. P. M. Kuin (UCL-MSSL), J. R. Cummings (CPI), J. Kennea (PSU),
A. Y. Lien (GSFC/UMBC),  K. Page (U. Leicester)
report on behalf of the Swift team

Further observations of GRB 150402A (Cummings and Palmer, GCN 17661) were 
carried out by the Swift observatory (Evans, GCN 17662).  We collected 4.8 ks of 
Photon Counting (PC) mode data between T0+108.4 ks and T0+121.6 ks, where T0 is 
the time of the BAT trigger.  One uncatalogued X-ray source has been detected 
inside or close to the Swift/BAT error region, it is below the RASS limit and 
shows no definitive signs of fading. Therefore, at the present time we cannot 
confirm this as the afterglow. Details of this source are given below:

   RA (J2000):  173.5883  =  11h 34m 21.19s
   Dec (J2000): +40.9398  =  +40 56â€² 23.3â€²â€²
   Error: 4.6 arcsec (radius, 90% conf.)
   Count-rate: (3.5 Â± 1.1)e-3 ct s^-1
   Flux: (1.7 Â± 0.5)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

One catalogued source was also detected too far from the BAT GRB position
to be a likely afterglow candidate.
     The UVOT observed in the uvw1 filter.  Close to the XRT position a star is 
seen in the DSS, which shows no evidence of an additional fading source 
contributing to the emission. The GRB upper limit is uvw1 > 18.63.
     Revised analysis of the BAT data yields a refined position of

   RA (J2000):  173.604 = 11h 34m 25.1s
   Dec (J2000): +40.988 = 40d 59' 18"

with an estimated uncertainty radius of 3.0 arcmin (90% containment). 
Mask-weighted data is available from T-2.0 to T+8.0 sec, which does not cover 
the entire burst, but we estimate T90 from the un-weighted data to be 14.4 +- 
1.6 sec (estimated error including systematics).  The available light curve 
shows two peaks, each about 4 seconds long. The time-averaged spectrum from 
T+0.0 to T+8.1 sec is best fit by a simple power-law model.  The power law index 
of the time-averaged spectrum is 2.29 +- 0.47.  The fluence in the 15-150 keV 
band is 1.5 +- 0.4 x 10^-7 erg/cm2. All the quoted errors are at the 90% 
confidence level.
     No further observations of this source are currently planned.


GRB_name: GRB150403A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17665
SUBJECT: GRB 150403A: Swift detection of a burst with an optical counterpart
DATE:    15/04/03 22:17:05 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), V. D'Elia (ASDC),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 21:54:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150403A (trigger=637044).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 311.505, -62.702, which is 
   RA(J2000)  =  20h 46m 01s
   Dec(J2000) = -62d 42' 04"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two overlapping peaks
with a total duration of about 60 sec.  The peak count rate
was ~19,000 counts/sec (15-350 keV), at ~7 sec after the trigger. 

The XRT began observing the field at 21:55:31.5 UT, 74.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 311.5019, -62.7118 which is equivalent to:
   RA(J2000)  = +20h 46m 0.46s
   Dec(J2000) = -62d 42' 42.5"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 35 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 6.34e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 84 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 20:46:01.14 = 311.50476
  DEC(J2000) = -62:42:41.0  = -62.71138
with a 90%-confidence error radius of about 0.61 arc sec. This position is 5.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.85 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.05. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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: GRB150403A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17666
SUBJECT: GRB 150403A: Enhanced Swift-XRT position
DATE:    15/04/04 09:28:12 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 3056 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 150403A, 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 = 311.50504, -62.71106 which is equivalent
to:

RA (J2000): 20h 46m 1.21s
Dec (J2000): -62d 42' 39.8"

with an uncertainty of 1.4 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: GRB150403A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17667
SUBJECT: GRB 150403A: Fermi-LAT detection
DATE:    15/04/04 10:12:54 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

F. Longo (University & INFN Trieste), E. Bissaldi (INFN Bari),
M. Arimoto (Tokyo Tech) and S. Zhu (UMD, USA)
report on behalf of the Fermi-LAT team:



At 21:54:10.95 on April 03, 2015, Fermi-LAT detected
high-energy emission from GRB 150403A, which was also
detected by Fermi-GBM (trigger 449790853/150403913)
and Swift (Lien at al, GCN 17665).

The GBM location was initially inside the LAT field
of view at an angle of ~55 degrees to the LAT boresight
and triggered an autonomous repoint of the spacecraft.

The best LAT on-ground location is found to be

RA, Dec (J2000)   311.79, -62.76

with an error radius of  0.50 deg (95% containment,
statistical error only) and consistent with the
enhanced Swift/XRT location (Beardmore et al, GCN 17666).

The data from the Fermi-LAT show a significant increase
in the event rate within 12 degrees of the Swift/XRT
location after the trigger.
More than 30 photons above 100 MeV are observed
within 2000 seconds. The highest-energy photon is a
5 GeV event which is observed 630 s after the GBM trigger.

Using the LAT Low Energy (LLE) data selection, over 200 counts
above background are detected within a 20 s interval coincident
with the time of the GBM emission.


The Fermi-LAT point of contact for this burst is
Sylvia Zhu (sjzhu@umd.edu).



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: GRB150403A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17668
SUBJECT: GRB 150403A: Swift-XRT refined Analysis
DATE:    15/04/04 10:17:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A.
Amaral-Rogers (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of
the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 150403A (Lien et al. GCN
Circ. 17665), from 64 s to 30.5 ks after the  BAT trigger. The data
comprise 3.5 ks 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 Beardmore
et al. (GCN Circ. 17666).

The late-time light curve (from T0+5.1 ks) can be modelled with a
series of power-law decays. The initial decay index is alpha=1.14
(+0.08, -0.15). At T+6776 s  the decay steepens to an alpha of 8.0
(+0.0, -2.7) before breaking again at T+7063 s to a final decay with
index alpha=1.42 (+0.14, -0.22).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.695 (+/-0.016). The
best-fitting absorption column is  1.03 (+/-0.05) x 10^21 cm^-2, in
excess of the Galactic value of 5.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.66 (+/-0.10) and a
best-fitting absorption column of 1.1 (+/-0.3) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.1 x 10^-11 (4.7 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.1 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 5.3 x 10^20 cm^-2
Excess significance: 2.9 sigma
Photon index:      1.66 (+/-0.10)

If the light curve continues to decay with a power-law decay index of
1.42, the count rate at T+24 hours will be 0.16 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x
10^-12 (7.7 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/00637044.

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


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17669
SUBJECT: GRB 150323C: Khureltogot optical observations
DATE:    15/04/04 11:07:51 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of 
Astronomy and Geophysics MAS),  A. Volnova (IKI), I.Molotov (KIAM), A. 
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 150323C (Amaral-Rogers  et al., GCN 17621) 
with ORI-40 telescope of Khureltogot observatory starting on Mar., 23 (UT) 
17:20:51, i.e. ~15 minutes after burst trigger. We obtained 180 unfiltered 
images of 60 s exposure. Within  enhanced Swift-XRT error circle (Osborne et 
al., GCN 17633)  we detect optical afterglow (Xu et al. GCN 17625, Xin et 
al. GCN 17631; Watson et al. GCN 17632). Preliminary photometry of the 
afterglow in combined images is following

Date        UT start  t-T0                  Filter      Exp.   OT  OT_err
                       (mid, days)                              (s)

2015-01-23  17:20:51  0.01449   none    10*60  21.1 0.3
2015-01-23  17:31:40  0.02199   none    10*60  20.5 0.25
2015-01-23  17:42:28  0.02950   none    10*60  20.8 0.25
2015-01-23  17:53:17  0.03700   none    10*60  20.2 0.2
2015-01-23  18:04:04  0.04451   none    10*60  20.0 0.2
2015-01-23  18:14:54  0.06199   none    35*60  21.3 0.3
2015-01-23  18:54:26  0.09409   none    39*60  21.0 0.3
2015-01-23  19:57:04  0.13649   none    40*60  21.5 0.4

Photometry is based on SDSS DR9 stars:

SDSS9_id                        R(Lupton)
J125026.13+501147.9  16.16
J125023.08+501048.2  16.84

Our photometry confirms  non-monotonic behaiviour of a lighr curve of the 
afterglow mentioned by Xin et al. (GCN 17631).
The light curve of GRB 150323C afterglow can be found in 
http://grb.rssi.ru/GRB150323C/GRB150323C_ORI40_lc.png 


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17670
SUBJECT: GRB 150323C: additional  optical observations in Mondy
DATE:    15/04/04 11:16:29 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev (ISTP), 
M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB 
follow-up collaboration:

We additionally observed the field of the GRB 150323C (Amaral-Rogers  et 
al., GCN 17621) with AZT-33IK telescope of Sayan observatory (Mondy) on 
Mar., 27 and Mar. 30 under good weather conditions and mean FWHV of 1.8 
arcsec. We obtained several images in R-filter of 120 s  exposure. In both 
epochs we detect a source in coordinates (J2000) 12 50 27.90 +50 11 29.0 
(+/- 0.45" ) which is within afterglow coordinates (Xu et al., GCN 17625) 
and within the enhanced Swift-XRT position (Osborne et al., GCN 17633). Our 
object is apparently the same object suggested as a possible host galaxy 
(Malesani et al., GCN 17655). Preliminary photometry of the source is 
following

Date       UT start           t-T0        Filter   Exp.       OT    Err.
                                       (mid, days)       (s)

2015-03-27 18:22:30   4.11333  R        85*120  22.7 0.25
2015-03-30 14:09:29   7.02068  R      194*120  22.3 0.15

Photometry is based on SDSS DR9 stars:

SDSS9_id            R(Lupton)
J125023.08+501048.2 16.84
J125032.04+501021.5 18.37

Also we note that our photometry reported early (Mazaeva et al., GCN 17639) 
may by significantly  be significantly influenced by the possible  host 
galaxy.


GRB_name: GRB150323C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17671
SUBJECT: GRB 150323C: CrAO optical observations
DATE:    15/04/04 11:23:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Rumyantsev (CrAO), K. Antoniuk  (CrAO), E. Mazaeva (IKI),  A. Pozanenko 
(IKI) report on  behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 150323C (Amaral-Rogers  et al., GCN 17621) 
with AZT-11 telescope of CrAO observatory starting on Mar. 23 (UT) 20:09:58. 
We obtained ages in R-filter of 180 s exposure under non-optimal weather 
conditions and mean FWHM of about 4.7 arcsec. In the enhanced XRT  position 
(Osborne et al., GCN 17633)  we do not detect  any object. In particular we 
do no detect optical afterglow (Xu et al. GCN 17625, Xin et al. GCN 17631; 
Watson et al. GCN 17632). An upper limit is following

Date              UT start,    t-t0          Filter   Exp.     OT   UL (3 
sigma)
                                        (mid, days)         (s)

2015-03-23 20:09:58   0.14949  R        20*180  n/d  21.0

The photometry is based on nearby USNO-B1.0  stars.


GRB_name: GRB150403A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17672
SUBJECT: GRB 150403A: VLT/X-shooter redshift
DATE:    15/04/04 12:06:05 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

V. Pugliese (API/Uva), D. Xu (DARK/NBI), N. R. Tanvir, K. Wiersema (U.
Leicester), J. P. U. Fynbo, B. Milvang-Jensen (DARK/NBI), V. D'Elia
(ASI/ASDC and INAF/Roma) report on behalf of a larger collaboration:

We observed the afterglow of GRB 150403A (Lien et al. GCN 17665; Longo
et al. GCN 17667) with X-shooter at the Very Large Telescope (Paranal
Observatory, Chile). Observations started at 08:44:48 UT on 2015-04-04
(i.e., 10.84 hr after the burst), and consisted of photometry in V-,
r-, z-, and g- bands as well as spectroscopy of 4x600 s exposures
covering the spectral range between 3000 and 25000 AA, equipped with
UVB/VIS/NIR arms.

The optical afterglow is well detected in each photometric image, and
has m(R) ~ 19.1 mag at 10.85 hr post-burst, calibrated with nearby
USNO B1 stars. For the spectroscopy, prominent absorption lines are
detected in a continuum throughout the arms. In a preliminary
reduction we detect absorption features of SII, SiIV, OI, SiII, SiII*,
CII, CII*, CIV, AlII, NiII*, FeII, FeII*, MnI, MgII, MgI at a common
redshift of z = 2.06, which is consistent with a broad Lya trough at
the same redshift. We suggest this is the redshift of the GRB.

We also detect an intervening system at z=1.76, identified with
absorption lines of SiII, CIV, AlII, and so on.

We acknowledge the excellent support provided by Paranal staff, and in
particular Andrea Mehner, and Emanuela Pompei.


GRB_name: GRB150403A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17673
SUBJECT: GRB 150403A: Swift/UVOT Detection
DATE:    15/04/04 13:51:07 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150403A
85 s after the BAT trigger (Lien et al., GCN Circ. 17665).    A source
consistent with the XRT position (Beardmore et al. GCN Circ. 17666)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  20:46:01.15 = 311.50479 (deg.)
    Dec (J2000) = -62:42:41.0  = -62.71139 (deg.)
with an estimated uncertainty of 0.42 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               85          235          147         14.89 +/- 0.02
v                  627          647           20         16.49 +/- 0.13
b                  553          573           20         16.65 +/- 0.08
u                  298          547          246         16.14 +/- 0.03
w1                 676         5286          294         19.68 +/- 0.21
m2                6317        23414         1178        >22.2
w2                5907         7536          387        >20.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB150403A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17674
SUBJECT: GRB 150403A: Fermi GBM Detection
DATE:    15/04/04 14:04:39 GMT
FROM:    Binbin Zhang at UAH  <binbin.zhang@uah.edu>

Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team:


"At 21:54:10.95 UT on 03 April 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150403A (trigger 449790853 / 150403913),
which was also detected by the Swift (Lien et al. 2015, GCN 17665)
and Fermi LAT (Longo et al. 2015, GCN 17667). The GBM on-ground
location is consistent with the Swift position. The trigger resulted
in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location. The initial angle
from the Fermi LAT boresight is about 55 degrees.


The GBM light curve shows a bright single pulse with a duration (T90)
of about 22.3 s (50-300 keV). The time-averaged spectrum from
T0+3.3 s to T0+25.6 s is best fit by a Band function with
Epeak = 311 +/- 14 keV, alpha = -0.72 +/- 0.02, and beta = -1.85 +/- 0.03.


The event fluence (10-1000 keV) in this time interval is
(5.73 +/- 0.05)E-05 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+11.1 s in the 10-1000 keV band
is 33.5 +/- 0.5 ph/s/cm^2.


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


â€”
Sent from Mailbox


GRB_name: GRB150403A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17675
SUBJECT: GRB 150403A: Swift-BAT refined analysis
DATE:    15/04/04 18:40:14 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), 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 (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150403A (trigger #637044)
(Lien, et al., GCN Circ. 17665).  The BAT ground-calculated position is
RA, Dec = 311.505, -62.706 deg which is
  RA(J2000)  =  20h 46m 01.1s
  Dec(J2000) = -62d 42' 20.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.

The mask-weighted light curve shows a single bright peak. The main structure
starts at ~ T-10 s, peaks at ~ T+6 s, and ends at ~ T+35 s. There are some
weaker emissions that starts at ~ T-170 s and lasts till ~ T+195 s. T90 (15-350 keV)
is 40.90 +- 11.72 sec (estimated error including systematics).

The time-averaged spectrum from T-83.15 to T+145.37 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.23 +- 0.04.  The fluence in the 15-150 keV band is 1.7 +- 0.03 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+5.80 sec in the 15-150 keV band
is 17.6 +- 0.6 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/637044/BA/


GRB_name: GRB150403A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17677
SUBJECT: Konus-Wind observation of GRB 150403A
DATE:    15/04/05 12:02:58 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long-duration, intense GRB 150403A
(Swift-BAT trigger #637044: Lien et al., GCN 17665;
Sakamoto et al., GCN 17675;
Fermi-LAT detection: Longo et al., GCN 17667;
Fermi-GBM detection: Zhang, GCN 17674)
triggered Konus-Wind at T0=78852.693 s UT (21:54:12.693).

The KW light curve shows a single bright pulse with a duration of ~26 s.
The emission is visible up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150403_T78852/

As observed by Konus-Wind, the burst had a fluence
of 1.0(-0.1,+0.1)x10^-4 erg/cm2, and a 64-ms peak flux,
measured from T0+9.088 s, of 1.7(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+27.136 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 = -0.93 (-0.07,+0.08),
the high energy photon index beta = -2.06 (-0.12,+0.08),
the peak energy Ep = 373 (-48,+58) keV,
chi2 = 124/97 dof.

The spectrum near the peak count rate
(measured from T0+7.168 to T0+10.752 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 = -0.78 (-0.08,+0.10),
the high energy photon index beta = -2.13 (-0.12,+0.09),
the peak energy Ep = 430 (-57,+64) keV,
chi2 = 117/97 dof.

Assuming the redshift z=2.06 (Pugliese et al., GCN 17672)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~1.0x10^54 erg,
the peak luminosity L_iso is ~5.3x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~1320 keV.


All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150404A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17678
SUBJECT: GRB 150404A: Fermi GBM detection
DATE:    15/04/05 14:00:24 GMT
FROM:    Hoi-Fung Yu at MPE  <sptfung@mpe.mpg.de>

H.-F. Yu (MPE) and M. Stanbro (UAH) report on behalf of the Fermi GBM Team:

"At 17:35:03.72 UT on 04 April 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150404A (trigger 449861706 / 150404733), 
which is also detected in optical by MASTER-SAAO (Tyurina et al., GCN 17676).

The on-ground calculated location, using the GBM trigger data, is
RA = 165.9, Dec = -67.4 (J2000 degrees, equivalent to 11h 04m, -67d 24'),
with an uncertainty of 8.9 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 about 84 degrees.

The GBM light curve consists of one single short pulse with a 
duration (T90) of about 4.8 s (50-300 keV). The time-averaged 
spectrum from T0-1.024 s to T0+2.048 s is best fit by a power law 
function with an exponential high-energy cutoff.  The power law 
index is -0.78 +/- 0.25 and the cutoff energy, parameterized as 
Epeak, is 90.9 +/- 14.1 keV.

The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.6)E-07 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+0.064 s in the 10-1000 keV band
is 3.2 +/- 0.3 ph/s/cm^2.

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


GRB_name: GRB150403A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17680
SUBJECT: GRB 150403A: MASTER-net optical observation
DATE:    15/04/06 17:24:35 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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


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 SAAO was pointed to the  GRB150403A (Lien et al. GCN 17665) 
20418 sec after notice time and 20434  sec (5.7h) after trigger time at 
2015-04-04 03:34:51 UT immediately after suitable weather condition came, 
in automatic mode. Observation lasted about 30 minutes, until the weather 
became bad again. We detect a faint OT on a Swift UVOT position (Kuin et al. GCN17673).
The estimated unfiltered magnitude is:

Date       time_start  T0-Tmid[s]  Expt.[s]   Mag  Coadd
2015-04-04 03:34:51.49  20840         720    19.2  4


Our unfiltered  band  is well described by a parity 0.8R+0.2B (USNO B1).

The message may be cited.


GRB_name: GRB150407A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17681
SUBJECT: GRB 150407A: Swift ToO observations
DATE:    15/04/07 19:18:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 150407A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020487

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150407A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17682
SUBJECT: GRB 150407A: Swift detection of a possible burst
DATE:    15/04/07 19:31:57 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

GRB 150407A: Swift detection of a possible burst

D. M. Palmer (LANL) reports on behalf of the Swift Team:

At 00:31:10, the Swift Burst Alert Telescope (BAT) detected
a possible source, GRB 150407A (trigger=637342), with marginal
statistical significance, in two consecutive images of 6 minutes 
total duration.
The BAT on-board calculated location is 
RA, Dec 216.603, 38.541 (J2000), which is 
  RA(J2000)  =  14h 26m 25s
  Dec(J2000) =  38d 32' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for image triggers, no obvious
variation is visible in the BAT lightcurve.

After ground discovery of this pair of possible detections, a ToO 
observation is planned to search for a counterpart afterglow.
See GCN#17681 for details.
-- 
David Palmer  palmer@lanl.gov   (505)665-6863 (voice)   (505)665-4414 (fax)


GRB_name: GRB150407A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17683
SUBJECT: GRB 150407A: optical observations
DATE:    15/04/07 23:02:42 GMT
FROM:    Klaas Wiersema at U Leicester  <kw113@leicester.ac.uk>

K. Wiersema (University of Leicester) reports on behalf of the Oadby 
Transients Team:

We observed the field of possible GRB 150407A (Palmer et al. GCN 17682) using the
0.5m telescope of the observatory of the University of Leicester, at Oadby (UK).
In a series of V band exposures, with midpoint 21.32 UT on 7 April 2015 (~0.88 days
after burst, GCN 17682), we find no source brighter than the DSS limit, in or near the 
BAT error circle (GCN 17682). 


GRB_name: GRB150407A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17684
SUBJECT: GRB 150407A: Swift-XRT observations
DATE:    15/04/08 07:39:54 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), A. Amaral-Rogers (U.
Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 150407A (Palmer et al. GCN Circ. 17682),
collecting 2.0 ks of Photon Counting (PC) mode data between T0+68.5 ks
and T0+70.5 ks. 

No X-ray sources have been detected inside or close to the Swift/BAT
error region. The 3-sigma upper limit in the field ranges from ~0.004
to ~0.009 ct s^-1, corresponding to a 0.3-10 keV observed flux of
1.4e-13 to 3.8e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020487.

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


GRB_name: GRB150402A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17685
SUBJECT: Swift GRB150402A: further XRT observations
DATE:    15/04/10 14:36:49 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <mdp@ifc.inaf.it>

M. De Pasquale (INAF-IASF Palermo) and H. Krimm (CRESST/GSFC/USRA)

Further 9.9 ks of XRT observations of GRB150402A (Cummings et al., GCN circ. 17661),
taken between T0+643.2 and T0+673.6 ks, show that the uncatalogued X-ray source
detected in the BAT error region (Krimm et al., GCN circ. 17664) is still detected
at a count rate of 3.9e-3 ct s^-1, showing no fading with respect to previous observations.
We therefore conclude that this source is not the X-ray afterglow of GRB150402A.
The 3 sigma upper limit calculated at the centre of the BAT error circle is 3.7e-3 ct s^-1.

This circular is an official product of XRT team.
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GRB_name: GRB150413A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17688
SUBJECT: GRB 150413A: Swift detection of a burst
DATE:    15/04/13 14:06:39 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

C. B. Markwardt (NASA/GSFC), M. M. Chester (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL)
report on behalf of the Swift Team:

At 13:54:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150413A (trigger=637899).  Swift did not slew immediately 
to the burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 190.385, +71.824 which is 
   RA(J2000) = 12h 41m 32s
   Dec(J2000) = +71d 49' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 120 sec.  The peak count rate
was ~1100 counts/sec (15-350 keV), at ~2 sec after the trigger. 

Due to an observing constraint, Swift cannot observe until
T0+4 days. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt 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: GRB150413A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17689
SUBJECT: GRB 150413A: MASTER bright OT detection 
DATE:    15/04/13 14:21:11 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory


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


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  GRB150413A (Markwardt et al. GCN 17688) 
132 sec  after trigger time at 2015-04-13 13:57:10 UT in two 
polarizations.

We see bright OT at:

RA, Dec = 12 41 41.98   +71 50 28.0
Mag = 16.1 (unfiltered 0.2B +0.8R UsnoB1)

The discovery image is available at
https://master.sai.msu.ru/static/OT/grb150413A.jpg
The message may be cited.


GRB_name: GRB150413A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17690
SUBJECT: GRB 150413A: MASTER very bright unusual OT observations  
DATE:    15/04/13 14:46:33 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

N.Tyurina, E. Gorbovskoy,  N.Tyurina, V.Kornilov, P.Balanutsa, 
A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute


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


D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory


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


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  GRB150413A (Markwardt et al. GCN 17688) 132 s.
After MASTER OT J124141.98+715028.0 detection (Ivanov et all, GCN 17689) 
we see obvious brightening on next 4 expozition sets in two polarizations.

After 18 min MASTER OT J124141.98+715028.0 is about 14.7 !



The message may be cited.


GRB_name: GRB150413A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17691
SUBJECT: GRB 150413A: MAXI/GSC detection
DATE:    15/04/13 15:09:31 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

M. Serino (RIKEN), H. Negoro (Nihon U.), S. Nakahira (JAXA),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
M. Nakajima, T. Namba, M. Fujita, F. Honda, K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, S. Kanetou (Chuo U.),
M. Yamauchi, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Morii (ISM)
report on behalf of the MAXI team:

At 13:56:30 UT, the MAXI/GSC nova alert system triggered a bright uncatalogued X-ray 
transient source at the position 
(R.A., Dec) = (190.278 deg,  71.742 deg) = (12 41 07, +71 44 31) (J2000).
The position is consistent with that reported by Markwardt et al. (GCN 17688).

The X-ray flux averaged over the scan was 440 +- 40 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 12:24
with an upper limit of 20 mCrab.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17692
SUBJECT: GRB 150413A: Khureltogot optical observations
DATE:    15/04/13 15:55:04 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Schmalz (AIP), A. Pozanenko (IKI),  N. Tungalag (Research Center of 
Astronomy and Geophysics MAS),   E. Mazaeva (IKI), A. Volnova (IKI), 
I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB 
follow-up collaboration:

We observed the field of the GRB 150413A (Markwardt  et al., GCN 17688; 
Serino et al., GCN 17691) with ORI-40 telescope of Khureltogot 
observatory starting on Apr., 13 (UT) 14:08:52, i.e. ~10 minutes after 
burst trigger.   Within   BAT/Swift  error circle  we clearly detect 
fading optical source  (Ivanov et al. GCN 17689, Tyurina et al. GCN 
17690). Preliminary photometry of the source in single images is following

Date        UT start   t-T0  Filter    Exp.   OT  OT_err
                       (mid, days)      (s)

2015-04-13  14:08:52   0.0069 none     60  14.7 0.1
2015-04-13  14:39:52   0.0318 none     60  15.6 0.1
2015-04-13  15:11:54   0.0541 none     60  16.3 0.1

Photometry is based on nearby USNO-B1.0 stars, R2 mags.
Observation is continuing.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17693
SUBJECT: GRB 150413A: Nanshan optical and radio follow-ups
DATE:    15/04/13 16:14:57 GMT
FROM:    Dong Xu at NAOC/CAS  <dong.dark@gmail.com>

D. Xu (NAOC), X. Zhang, C.-H. Bai, G.-J. Feng, A. Esamdin, L. Ma,
J.-Z. Liu (XAO), Y. Qin (Geneva Observatory), J.-P. Yuan, Z.-G. Wen
(XAO) report:

We observed the field of GRB 150413A (Markwardt et al., GCN 17688;
Serino et al., GCN 17691) using the 1m telescope located at Nanshan,
Xinjiang, China. Observations started at 15:00:38 UT on 2015-04-13,
i.e., 1.09 hr after the burst and a series of 150s R-band images were
obtained and observations are ongoing.

The OT reported by MASTER (Ivanov et al., GCN 17689; Tyurina et al.,
GCN 17690) is within the BAT error circle, and it is clearly detected
in each of our images. Preliminary reduction shows that the OT has
been decaying very slowly since our observations. It has m(R) ~ 15.4
at 1.115 hr post-burst and has m(R) ~ 15.8 at 1.724 hr post-burst,
calibrated with the same USNO B1 star (#1618-0098185, R=15.59, close
to R1=16.02). The OT's lightcurve behavior is unusual compared to
normal GRB optical afterglows, although it indeed could be the
afterglow of the GRB.

We note that there is a bright and much extended galaxy within the BAT
error circle. However, we didn't find any apparent new point source
within the galaxy, compared to DSS.

In addition, we observed the field using the Nanshan 25m radio dish in
the pulsar searching mode, to check if there is any radio pulse mimicking a fast
radio burst and following the BAT trigger.

[GCN OPS NOTE(21apr15):  Per author's request, the mode in the last sentence
was changed from "timing mode" to "pulsar searching mode".]


GRB_name: GRB150413A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17694
SUBJECT: GRB 150413A: Tautenburg observations
DATE:    15/04/13 19:50:02 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>

S. Klose, S. Schmidl, B. Stecklum, A. Nicuesa Guelbenzu, D. A. Kann, and 
F. Ludwig (TLS Tautenburg) report:

Tautenburg observed the afterglow of GRB 150413A (Markwardt et al., GCN 
17688; Ivanov et al., GCN 17689; Tyurina et al., GCN 17690; Serino et al., 
GCN 17691; Schmalz et al., GCN 17692; Xu et al., GCN 17693) with the 1.34m 
Schmidt telescope under good weather conditions.

At a mean time of 19:23 UT we measure a preliminary magnitude of R = 17.2 
+/- 0.1, calibrated against the USNO B1 star #1618-0098185 (Xu et al.).

Observations are continuing.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17695
SUBJECT: GRB 150413A: Khureltogot optical observations
DATE:    15/04/14 02:02:12 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Schmalz (AIP),   N. Tungalag (Research Center of Astronomy and Geophysics 
MAS),   A. Pozanenko (IKI),  E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov 
(KIAM), report on behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 150413A (Markwardt  et al., GCN 17688; 
Serino et al., GCN 17691) with ORI-40 telescope of Khureltogot observatory 
starting on Apr., 13 (UT) 14:08:52 and finishing on Apr. 13 (UT) 20:08:39. 
The afterglow   (Ivanov et al., GCN 17689, Tyurina et al., GCN 17690, 
Schmalz  et al., GCN 17692, Xu et al., GCN 17693, Klose et al., GCN 17694) 
is detected up to the end of our observations. Preliminary light curve 
obtained for single unfiltered images and calibrated against nearby 
USNO-B1.0 stars (R2 mags) can be found in 
http://grb.rssi.ru/GRB150413A/GRB150413A_ORI40_lc.jpg

In particular, our photometry on Apr., 13 (UT) 19:21:35 R=17.2+/-0.1 is 
compatible with photometry at (UT) 19:23 reported by Klose et al. (GCN 
17694).


GRB_name: GRB150413A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17696
SUBJECT: GRB 150413A: P60 photometry
DATE:    15/04/14 04:41:01 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

The Palomar 60-inch telescope observed the location of the optical 
counterpart of GRB 150413A (Markwardt et al., GCN 17688; Ivanov et al., 
GCN 17689) starting at 03:15:21 UT on 2015-04-14.  We acquired 3x180s 
images in griz filters under good conditions.

The optical transient is well-detected in all four filters.  Calibrating 
relative to USNO stars in the field, we measure a magnitude of R = 19.1 
(+/- 0.1) mag at this time (t = 0.560 days after the BAT trigger), 
indicating significant fading since the early observations.

Further follow-up is planned.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17697
SUBJECT: GRB 150413A: redshift determination with the 2.2m CAHA
DATE:    15/04/14 10:34:25 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

R. Sanchez-Ramirez (UPV/EHU, IAA-CSIC), A. J. Castro-Tirado (IAA-CSIC,
ISA-UMA), F. Hoyos and J. Aceituno (CAHA), on behalf of a larger
collaboration, report:

Following the detection of GRB 150413A by Swift (Markwardt et al. GCNC
17688) we have obtained a 1200s+1800s spectrum at the position of the
optical afterglow (Ivanov et al. GCNC 17689, Serino et al. GCNC 17691,
Schmalz et al. GCNC 17692, Xu et al. GCNC 17693, Klose et al. GCNC 17694).
Observations were carried out with the 2.2m CAHA telescope (+ CAFOS) at
the German-Spanish Calar Alto Observatory, starting at 20:25 UT. (i.e. 6.5
hr post-burst) under poor weather and seeing conditions. After a
preliminary reduction, we have detected a broad absorption line which we
identify as Lyman-alpha at a reshift of z = 3.2. Due the low SNR of the
combined spectrum, we only detect several lines at low significance (Ni
II, Si IV, C IV, Fe II,) consistent with this redshift, which we propose
to be the redshift of GRB 150413A.

We acknowledge excellent support of the CAHA staff.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17698
SUBJECT: GRB 150413A: optical observations
DATE:    15/04/14 12:12:40 GMT
FROM:    Klaas Wiersema at U Leicester  <kw113@leicester.ac.uk>

I. van de Stadt (AWSV Metius, Alkmaar, The Netherlands) and
K. Wiersema (U. of Leicester) report:

We observed the field of GRB 150413A (Markwardt  et al. GCN 17688;
Ivanov et al., GCN 17689) using the ABT, a 10-inch remote controlled
observatory in Alkmaar, The Netherlands. In a series of I band exposures,
with midpoint 0.55 days after burst, the afterglow is not detected, with
a 5-sigma upper limit of 18.7 mag (calibrated using APASS field stars and
the Jordi et al. (2005) conversions). This limit is in agreement with the
light curve break seen by Schmalz et al. (GCN 17695).


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17700
SUBJECT: GRB150413A, optical observations                                                
DATE:    15/04/14 13:57:16 GMT
FROM:    Kosmas Gazeas at U of Athens  <kgaze@phys.uoa.gr>

Kosmas Gazeas and Konstantinos Sapountzis (National Univ. of Athens) report:

On 13 April 2015, we observed the GRB candidate optical counterpart
GRB150413A, as reported by Markwardt et al., GCN 17688 and Serino et al., GCN
17691. The observations have been obtained with the 0.40 m f/8 robotic
telescope at the University of Athens in R-band (Bessell specifications). Data
collection has started on Apr., 13 (UT) 17:38:58 and finishing on Apr. 13 (UT)
18:08:08 (mid-exposure time). A sum of 15 exposures of 120 sec each was
collected and all data were combined into a single image, although the optical
afterglow was barley seen in each individual exposure. Photometry with a 3
pixel (approximately 4 arcsec) radius aperture yields an R magnitude
estimation of R = 17.9 +- 0.3 mag for GRB150413A, as compared with respect to
the nearby USNO-B1.0 stars, which lie within a radius of 3-4 arcminutes around
the source. No absolute photometric calibration has been applied on these data.

This message is quotable in publications.


GRB_name: GRB150413A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17701
SUBJECT: GRB 150413A: Swift-BAT refined analysis
DATE:    15/04/14 14:03:03 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@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 (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150413A (trigger #637899)
(Markwardt, et al., GCN Circ. 17688).  The BAT ground-calculated position is
RA, Dec = 190.396, 71.839 deg which is
  RA(J2000)  =  12h 41m 35.1s
  Dec(J2000) = +71d 50' 21.9"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-100 s and ends at ~ T+200 s. The most prominent pulse starts at ~ T+90 s,
peaks at ~ T+110 s, and ends at ~ T+120 s. T90 (15-350 keV) is 263.6 +- 36.7 sec
(estimated error including systematics).

The time-averaged spectrum from T-93.0 to T+209.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.75 +- 0.14.  The fluence in the 15-150 keV band is 4.3 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+110.78 sec in the 15-150 keV band
is 1.6 +- 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/637899/BA/


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17702
SUBJECT: GRB 150413A: T7 and T18 optical observations
DATE:    15/04/14 14:37:36 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 150413A optical afterglow at iTelescope
observatory T7 and T18 (AstroCamp Observatory, Nerpio, Spain)
using T7 0.43-m/6.8  and T18 0.32-m/8.0 astrographs. The observations
were started at 2015-04-13 20:29:13 (UT) and stopped at 23:54:26
(UT). Fifteen unfiltered images and four photometric R filter images with
120 sec exposure time were made.

The afterglow was detected at the following position RA 21:41:41.88
and DEC +71:50:27.9.

The following magnitude were obtained from the observations using
USNO-B1.0 1618-0098208 (R1=14.38) as a comparison star:

Telescope   Tmid(h)+T0    Filter             Exp. time         Mag
T7                6.611          unfiltered        2x120s          17.2CR  
T7                6.728          unfiltered        3x120s          17.4CR  
T7                6.976            R                 2x120s          17.7R 
T7                7.184            R                 2x120s          17.9R 
T18              9.508          unfiltered        4x120s          18.0CR
T18              9.685          unfiltered        4x120s          18.0CR
T18              9.904          unfiltered        2x120s          18.0CR

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GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17704
SUBJECT: GRB 150413A: Bassano Bresciano Observatory optical observations
DATE:    15/04/14 15:49:55 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs  <oabb@ulisse.bs.it>

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

We imaged the field of GRB 150413A detected by SWIFT(trigger 637899)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy (member of ISSP:Italian Supernovae Search Project)

The observations started 5.44 hour after the GRB trigger, at the end of twilight, 
with our schmidt telescope D=320/400 mm F/D=3.1.

Weather conditions were good.

We co-added 13 series of 10 exposures of 120 sec each.

Start T0+      End T0+      Vlim
---------------------------------
5.44 hour    10.26 hour     19.5

We clearly detect the optical counterpart
at the following coordinates:

12h 41m 41.78s +71d 50m 27s +-2 arcsc.

Magnitudes were estimated with the UCAC4 cat. 
and are not corrected for galactic dust extinction:

----------------------
      JD        CV mag  
----------------------
2457126.30650   17.92 
2457126.32100   17.94 
2457126.33532   18.10 
2457126.34963   17.83 
2457126.36395   17.99 
2457126.37827   18.02 
2457126.39258   18.21 
2457126.40691   18.10 
2457126.42122   18.21 
2457126.43482   18.28 
2457126.47849   18.54 
2457126.49282   18.78 
2457126.50714   19.20 

The image, and magnitude plot are available at:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17705
SUBJECT: GRB 150413A
DATE:    15/04/15 02:02:25 GMT
FROM:    Matteo M. M. Santangelo at OAC  <oac@irf.lu.it>

M.M.M. Santangelo and S. Gambogi report:

We performed R and I bands CCD imagery of the field of GRB 150413A
with the 0.60-meter f/9.83 Cassegrain reflector of Capannori Astronomical Observatory, Italy.
Weather conditions were good, the seeing was fairly good, and the night-sky brightness
at zenith was 20.15 mag/arcsec2 in V band.
We clearly detected the optical counterpart of GRB 150413A.
Magnitudes in Johnson/Cousins R and I bands derived by means of Mira professional 7 UE software are as follows:

Date           UT         Exposure   Band   mag Â± sigma
2015-04-13   20:56:22   300 s    I   17.2 Â± 0.2
2015-04-13   21:04:43   180 s    R   17.6 Â± 0.1
2015-04-13   21:11:02   360 s    I   17.29 Â± 0.04

Photometry is based on the nearby GSC 4397:1311 star, with magnitudes of comparison star from PPMXL.
This message may be cited.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17706
SUBJECT: GRB 150413A : Virtual Telescope optical observations
DATE:    15/04/15 10:22:35 GMT
FROM:    Gianluca Masi at Bellatrix Astronomical Obs  <gianluca@bellatrixobservatory.org>

G. Masi and P. L. Catalano, the Virtual Telescope Project - Italy, report:

We started time-series observations of GRB 150413A (C. B. Markwardt et al., GCN 
17688) with the 17" robotic unit part of the Virtual Telescope (Ceccano, Italy) 
at 21:25:00 UT, that is 7.5 hours after the burst.

An optical source is visible where described by K.Ivanov et al. (GCN 117689) on 
60s and 120s exposures, unfiltered. The position of the source is RA: 12 41 
41.97 Decl.: +71 50 27.7 (J2000, mean residuals of 0.2") and the magnitude was 
estimated to be 18.0, assuming R mags for the reference stars from UCAC-4.

We covered the source for about one hour, detecting a fadind of about 0.4 mags 
from the start to the end of the series.

Details are available on the page:
http://goo.gl/8jCkhs

This message can be cited.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17707
SUBJECT: GRB 150413A: additional P60 observations
DATE:    15/04/15 11:29:50 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

We have continued to follow the optical counterpart of GRB 150413A 
(Markwardt et al., GCN 17688; Ivanov et al.,  GCN 17689) with the 
Palomar 60-inch robotic telescope.  A second griz epoch was acquired 
between 10:08:52 and 10:49:31 UT on the night of 2015-04-14, followed by 
two deeper epochs (one gri, one r only) on the night of UT 2015-04-15.

Calibrating our r-band observations to a common set of USNO R-band 
reference stars, we derive the following photometry (statistical 
uncertainties only):

dt_mid = 0.5602 day :  R = 19.13 +/- 0.03
dt_mid = 0.8464 day :  R = 20.23 +/- 0.06
dt_mid = 1.6034 day :  R = 21.52 +/- 0.16
dt_mid = 1.8652 day :  R = 21.74 +/- 0.18

This suggests steep decay over this period (decay index ~ 2.2).


GRB_name: GRB150413A
Detection_method: AMI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17708
SUBJECT: GRB 150413A: AMI 15 GHz detection of possible radio counterpart
DATE:    15/04/15 17:47:38 GMT
FROM:    Alexander van der Horst at George Washington U  <ajvanderhorst@gwu.edu>

G.E. Anderson, R.P. Fender, T.D. Staley, K. Mooley (University of Oxford),
A.J. van der Horst (George Washington University), A. Rowlinson (CASS)

We observed the position of GRB 150413A (Markwardt et al., GCN 17688)
at 15 GHz with the Arcminute Microkelvin Imager (AMI-LA) starting on
2015 April 14.745 to 14.973 UT, corresponding to 1.2 days post-burst.
On this date we possibly detected a radio source coincident with the
MASTERs optical position (Ivanov et al., GCN 17689) with a preliminary
flux of 0.19 +/- 0.04 mJy. There are no catalogued radio sources at this 
position.

An earlier observation was conducted on 2015 April 13.747 to 13.914 UT,
corresponding to 0.2 days post-burst, yielding a 3 sigma flux upper limit
of 0.15 mJy.

Further AMI monitoring is planned. We thank the AMI staff for scheduling 
these observations.


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17709
SUBJECT: GRB 150413A: GMG observation
DATE:    15/04/16 04:29:34 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, C. Wang and J.-M. Bai report:


We observed the field of GRB 150413A (Markwardt et al., GCN 17688) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG)
 station of Yunnan Observatory. Observations began from 13:35:29 UT, April 14, 2015, about 23.7 hours after the trigger. We
marginally detected the optical counterpart and estimated the magnitude as I~20.3.


GRB_name: GRB150413A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17710
SUBJECT: GRB 150413A: Refined redshift
DATE:    15/04/16 20:59:00 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI) and L. Tomasella (INAF-OAPd) 
report:

We have reanalysed the spectra of the afterglow of GRB 150413A (Markwardt 
et al. GCN 17688, Ivanov et al. GCN 17689) obtained by the Asiago Transient 
Classification Program (Tomasella et al. 2014, AN, 335, 841) with the Asiago 
1.82 m Copernico Telescope +AFOSC (Tomasella et al. ATel 7391). In addition 
to the Ly-alpha feature already reported, we identify absorption features of SiII, 
SiII*, CII, SiIV, CIV, FeII and AlII at a common redshift of 3.139+/-0.003, slightly 
lower than previously reported by Sanchez-Ramrez (GCN 17697) and by 
Tomasella et al. (ATel 7391). In addition we report a tentative detection of a MgII 
intervening absorber at z=0.950+/-0.003.


GRB_name: GRB150416A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17711
SUBJECT: GRB 150416A: Fermi-LAT detection 
DATE:    15/04/17 04:28:57 GMT
FROM:    Daniel Kocevski at GSFC  <daniel.kocevski@nasa.gov>

D. Kocevski (NASA/Goddard) and E. Bissaldi (INFN Bari) report on behalf of the Fermi-LAT team:

At 18:33:32 UT on April 15th, 2015, Fermi-LAT detected emission from GRB 150416A, which was also detected by Fermi-GBM (trigger 450902008/150416773).

The GBM location was initially outside the LAT field of view at an angle of ~68 degrees to the LAT boresight. Therefore, no observations of events > 100 MeV are available during the emission observed by the GBM.

Using the LAT Low Energy (LLE) data selection, over 25 counts above background were detected within a 50 s interval coinciding with the time of the GBM emission. This data selection has insufficient spatial resolution to provide a reliable LAT localization.

The Fermi-LAT point of contact for this burst is Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it<mailto:elisabetta.bissaldi@ba.infn.it>).

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: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17713
SUBJECT: LOAO B, R Observations of GRB150413A
DATE:    15/04/17 06:54:10 GMT
FROM:    Changsu Choi at Seoul Nat U  <changsu@astro.snu.ac.kr>

Changsu Choi, Myungshin Im (CEOU/SNU), Hyun-Il Sung (KASI), and Yuji Urata
(NCU), on behalf of EAFON

We observed the field of GRB 150413A, Swift GRB 150413A (Markwardt et al.,
GCN
17688) in B,R-band using the 1-m telescope at Mt. Lemmon Optical Observatory
(LOAO) in Arizona, US

We obtained B, R-band images on Apr. 14.
We identified the optical afterglow in both band.
The photometric calibraton is based on APASS catalog(AAVSO) in the observed
field.

Details of Photometry are below:

UT                               Filter       Mag                 Hour
after detetion trigger(2015/04/13T 13:54:58)
2015/04/14T 04:54:07    B            20.95 +-0.25    15.13583

2015/04/14T 05:08:05    R            19.82 +-0.14    15.36861


GRB_name: GRB150413A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17714
SUBJECT: GRB 150413A: SAO RAS observations
DATE:    15/04/17 11:23:58 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin (SAO RAS) report on behalf of larger GRB follow-up
collaboration:

The field of GRB 150413A (Markwardt et al., GCNC 17688) was observed
with the Zeiss-1000, 1-m telescope of SAO RAS. The observations were
carried out on the April, 16, 20:00:28--21:31:31 UT (T-T0 = 3.285 days).
16 x 300 sec. frames in Rc filter were obtained. The OT (Ivanov et al.,GCNC
17689)
is absent in the stacked image, therefore R > 23.0.  The limiting value is
based on
the R2 magnitudes of nearby USNO-B1 stars.

We acknowledge A. S. Pozanenko, O. I. Spiridovova and V. S. Bychkova
for the help in observations.


GRB_name: GRB150413A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17715
SUBJECT: GRB 150413A: MITSuME Akeno Optical observation
DATE:    15/04/17 13:17:03 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

T.Fujiwara, Y. Saito, T. Yoshii, Y. Tachibana, H. Ohuchi, 
Y. Yano, S.Kurita, Y. Ono, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 150413A (C. B. Markwardt et al. GCN Circular #17688) 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 2015-04-13 15:58:02 UT (~2.1 h after the burst).
We detected the previously reported optical afterglow (K.Ivanov et al. GCN Circular #17689) in the Ic band.

The measured magnitudes are listed below.

T0+  MID-UT  T-EXP[sec]    g'                Rc             Ic
----------------------------------------------------------------------
263 min   4/13 18:17:28  240     > 17.3  > 17.2  16.09 +/- 0.30
2.04 days   4/15 14:52:50  15960    > 21.7  > 21.5  > 20.2
----------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB150416A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17717
SUBJECT: GRB 150416A: Fermi GBM detection
DATE:    15/04/17 18:32:07 GMT
FROM:    Peter Jenke at MSFC  <peter.a.jenke@nasa.gov>

P. Jenke (UAH) reports on behalf of the Fermi GBM Team:

"At 18:33:25.97 on April 16 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150416A (trigger 450902008/150416773) which
was also detected by Fermi-LAT (D. Kocevski et al., GCN 17711)
The GBM on-ground location, using the Fermi GBM trigger
data, is RA = 58.8, Dec = 53.0 (J2000 degrees, equivalent to 
3h 55m 00s, 53d 0), with an uncertainty of 1.9 
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 of the burst direction to the Fermi LAT boresight is 
68 degrees.

The GBM light curve consists of two peaks with a duration
(T90) of about 33 s (50-300 keV).
The time-averaged spectrum from T0+0s to T0+34.8s 
is well fit by a BAND function with Epeak = 940 +/- 160 keV, 
Alpha = -0.9 +/- 0.05 and Beta = -2.1 +/- 0.2. 
The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.04)E-05 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+12.8 s in the 10-1000 keV band
is 3.8 +/- 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: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17718
SUBJECT: GRB 150413A: ISON-Ussuriysk optical observations
DATE:    15/04/17 21:33:14 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  A. Stepura (UAFO, ISON),  A. Matkin (UAFO, ISON), A. 
Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the GRB 150413A (Markwardt  et al., GCN 17688) 
with SANTEL-650 (0.65m)  telescope of UAFO/ISON-Ussuriysk observatory 
sstarting on Apr., 14 (UT) 11:48:05.   The afterglow   (Ivanov et al., GCN 
17689) is clearly detected in a combined image. Preliminary photometry the 
unfiltered combined image  is following

Date            UT start   t-T0        Filter     Exp.     OT      OT_err
                                 (mid, days)          (s)

2015-04-14  11:48:05  0.95859   none     117*60  20.35   0.15

The photometry is based on nearby USNO-B1.0  stars 


GRB_name: GRB150418A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17719
SUBJECT: GRB 150418A: MAXI/GSC detection
DATE:    15/04/18 01:50:23 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

GRB 150418A: MAXI/GSC detection
M. Serino (RIKEN), H. Negoro (Nihon U.), S. Nakahira (JAXA),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
M. Nakajima, T. Namba, M. Fujita, F. Honda, K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, S. Kanetou (Chuo U.),
M. Yamauchi, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Morii (ISM)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 00:52:08 UT.
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(159.791 deg, -4.326 deg) = (10 39 09, -04 19 34) (J2000)
(159.898 deg, -4.194 deg) = (10 39 35, -04 11 39) (J2000)
(161.225 deg, -5.494 deg) = (10 44 53, -05 29 39) (J2000)
(161.114 deg, -5.624 deg) = (10 44 27, -05 37 25) (J2000)
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 597 +- 45 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 23:19 on
April 17 with an upper limit of 20 mCrab.


GRB_name: GRB150418A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17720
SUBJECT: GRB 150418A: Tiled Swift observations
DATE:    15/04/18 04:28:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 150418A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00041

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150413A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17721
SUBJECT: GRB 150413A: RTT150 optical observations
DATE:    15/04/18 09:36:15 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

I. Bikmaev, E. Irtuganov, N. Sakhibullin (KFU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Khamitov, H. Kirbiyik (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)

report:

The field of the optical afterglow of GRB 150413A (Markwardt et al.,
GCN 17688, Ivanov et al., GCN 17689) was observed with Russian-Turkish
1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory,
Turkey) using the TFOSC instrument.

We obtained series of Rc exposures in April 13/14 (50 frames x 300
sec, UT = 20:27 - 02:30 ) and in April 14/15 (4 frames x 600 sec,
UT = 22:43 - 00:28, in partially cloudy conditions). The optical
transient is clearly detected in each images.

Using USNO-B1 1618-0098185 star at RA,DEC = 12:41:09.18 +71:50:32.4
(J2000) with R2 = 15.59 mag as a reference we estimated the
R-magnitudes of the afterglow:

T-T0, Mag. +/- Mag.err
(days)
0.2932 17.39 +/- 0.03
0.5200 18.70 +/- 0.05
1.4318 21.4  +/- 0.2

RTT-150 light curve in April 13/14, 2015, can be found at:

http://hea.iki.rssi.ru/grb/150413a/indexeng.html

The break in the light curve at (T-T0) = 0.33 days is evident (break
is seen also in V-band data of Bassano Bresciano Observatory, Quadri
et al, GCN 17704).

Before the break at (T-T0) = 0.33 days, the power law decay index is
=~0.9, and it is close to 3.0 after that. Note, that decay index is
close to 2.0 after (T-T0) = 0.7 days. Therefore, there are multiple
breaks in the OT light curve.


GRB_name: GRB150418A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17722
SUBJECT: GRB 150418A: Swift-XRT observations
DATE:    15/04/18 20:33:05 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

B. Sbarufatti (INAF-OAB/PSU), A. Amaral-Rogers (U. Leicester), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo
(INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N.
Burrows (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report
on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 150418A (Serino et al. GCN Circ. 17719) in a series of
observations tiled on the sky. The total exposure time is 3.7 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 1.5 ks. The data were collected between T0+12.9 ks and T0+32.6 ks,
and are entirely in Photon Counting (PC) mode. 

Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:

Source 1:
  RA (J2000):  160.2608  =  10:41:2.60
  Dec (J2000): -4.7593  =  -04:45:33.5
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: 0.0124 [+0.0060, -0.0047] ct s^-1
  Flux: (5.0 [+2.4, -1.9])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000):  160.6825  =  10:42:43.80
  Dec (J2000): -5.3357  =  -05:20:08.4
  Error: 5.8 arcsec (radius, 90% conf.)
  Count-rate: 0.0215 [+0.0089, -0.0074] ct s^-1
  Flux: (8.6 [+3.6, -3.0])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00041.

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


GRB_name: GRB150413A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17723
SUBJECT: GRB 150413A: Swift-XRT observations
DATE:    15/04/20 09:26:50 GMT
FROM:    Claudio Pagani at U of Leicester  <cp232@star.le.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.
Leicester), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), A. Maselli 
(INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) and C. B. Markwardt (NASA/GSFC) report on behalf of the
Swift-XRT team:

We have analysed 6.2 ks of XRT data for the Swift/BAT-detected burst
GRB 150413A (Markwardt et al., GCN Circ. 17688). The data are entirely
in Photon Counting (PC) mode, collected between T0+303.3 ks and
T0+550.9 ks. 

No X-ray sources have been detected inside or close to the Swift/BAT
error region. The 3-sigma upper limit at the position of the optical
afterglow (Ivanov et al., GCN Circ. 17689) is 0.003 ct s^-1,
corresponding to a 0.3-10 keV observed flux of 1.2e-13 erg cm^-2 s^-1
(assuming a typical GRB spectrum).

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00637899.

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


GRB_name: GRB150418A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17725
SUBJECT: Further Swift XRT observations of GRB 150418A
DATE:    15/04/20 17:39:18 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

B. Sbarufatti (INAF-OAB/PSU), L. Hagen (PSU) report on behalf of the Swift team

Swift performed a follow up observation of GRB 150418A, with a pointing  in the direction of Source #1 reported by Sbarufatti et al. (GCN Circ. 17722).
In 3.7 ks of exposure we donâ€™t detect any X-ray source down to a 3-sigma upper limit of 9.8 E-3 counts/s in the position of Source 1.
We note that this new observation and the original one are both affected by a higher than usual background, which may have led to spurious detections of background fluctuations as Sources #1 and #2.

No further Swift observations of this field are planned.

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


GRB_name: GRB150418A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17726
SUBJECT: GRB150418A: Swift/UVOT did not detect a new source
DATE:    15/04/21 23:05:38 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N.P.M. Kuin (UCL/MSSL) reports on behalf of the Swift UVOT team:

Swift UVOT observations were made concurrently with the XRT observations
reported by  Sbarufatti et al. (GCN Circ. 17722 and 17725) of
GRB 150418A which was discovered by MAXI (Serino et al., GCN Circ.
No. 17719). At the location of the possible X-ray source detections
named source 1 and source 2 no new source was detected in the
u-band, with the following limits:

Source 1: u > 22.9 at 72.2 ks since the MAXI trigger at
    2015-04-18T00:52:08UT for an exposure time of 3.9ks
Source 2: u > 21.17 at t = 19ks since the MAXI trigger,
    for an exposure time of 322s.

However, we note that source 1 is at a distance of 4.6 arcsec of
a known nearby source in GSC2.3 (designated S5FU004949). That
source was detected with a magnitude u=20.38 +/- 0.15.

No correction was made for the galactic reddening
of E(B-V) = 0.043 and 0.373 respectively (Schlafly & Finkbeiner
2011 (ApJ 737, 103) ) at the locations of the sources 1 and 2.


GRB_name: GRB150418A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17727
SUBJECT: Konus-Wind observation of GRB 150418A
DATE:    15/04/22 13:12:44 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long GRB 150418A localized by MAXI/GSC (Serino et al., GCN 17719)
was detected by Konus-Wind in the waiting mode.

The burst light curve shows a double-peaked structure
started at ~T0(MAXI)-16 s with a total  duration of ~29 s.

As observed by Konus-Wind, the burst had a fluence of
2.94(-0.37,+0.47)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(MAXI)+5 s, of 2.71(-0.37,+0.49)x10^-7 erg/cm2/s
(both in the 20 - 1200 keV energy range).

Fitting the K-W 3-channel time-integrated spectrum (from ~T0(MAXI)-16 s
to ~T0(MAXI)+14 s) by a simple power-law model yields a power law index
of -2.24(-0.17,+0.17), chi2=0.04/1 dof.

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

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB150418A/


GRB_name: GRB150423A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17728
SUBJECT: GRB 150423A: Swift detection of a short burst
DATE:    15/04/23 06:42:58 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

C. Pagani (U Leicester), V. D'Elia (ASDC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and T. N. Ukwatta (LANL) report on behalf of the
Swift Team:

At 06:28:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150423A (trigger=638808). Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 221.600, +12.288 which is 
   RA(J2000) = 14h 46m 24s
   Dec(J2000) = +12d 17' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). The BAT light curve showed a single peak 
with a duration of about 0.5 sec. The peak count rate was ~6400 
counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 06:29:14.8 UT, 70.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 221.5787, 12.2833 which
is equivalent to:
   RA(J2000)  = 14h 46m 18.90s
   Dec(J2000) = +12d 16' 60.0"
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This
location is 76 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 1.77
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 73 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 29% 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 C. Pagani (cp232 AT star.le.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: GRB150423A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17729
SUBJECT: GRB 150423A: GROND observation
DATE:    15/04/23 07:35:54 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

K. Varela, F. Knust, J. Bodensteiner and J. Greiner (all MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 150423A (Swift trigger 638808; Pagani et al.,
GCN #17728) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 06:32 UT on 2015-04-23, 4 min after the GRB
trigger. They were performed at an average seeing of 0".8 and at an
average airmass of 1.5.

We detect a faint source within the 2.2" XRT error circle, at position

RA (2000.0) = 14h 46m 18.9s
Decl (2000.0) = +12d 17' 00"

with an error of 0.5", about 1" away from the XRT centroid position.

Based on 7.7 min of total exposure time in g'r'i'z' and 8.0 min in JHK, 
centered 24 min after the GRB, we estimate the following preliminary
magnitudes (all in AB system):

g' = 23.2 +/- 0.2 mag,
r' = 23.1 +/- 0.2 mag,
i' = 22.5 +/- 0.2 mag,
z' = 22.0 +/- 0.2 mag,
J  = 19.3 +/- 0.4 mag,
H  > 18.4  mag, and
K  > 17.5 mag.

No statement can be made about fading at this stage. Since there is a
faint source also in the SDSS, this might be the host galaxy rather than
the afterglow.

Given magnitudes are calibrated against SDSS (g'r'i'z') as well as 2MASS 
field stars and are not corrected for the expected Galactic foreground 
extinction corresponding to a reddening of E_(B-V)=0.03 mag in the 
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17730
SUBJECT: GRB 150423A: KAIT Optical Upper Limit
DATE:    15/04/23 07:45:42 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150423A (Pagani et al.,
GCN 17728) starting at 06:30:00 UT, 116 s after the burst, under
thin-cloudy condition. Observations were performed with an
automatic sequence in the clear (roughly R), V, and I filters, and
the exposure time was 20 s per image. We do not detect the optical
source reported by Varela et al. (GCN 17729), in our images, nor
any other new source within the XRT error circle. The typical
limiting magnitude of our single clear image is about 17.0
calibrated to USNO B1.0.


GRB_name: GRB150413A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17731
SUBJECT: GRB 150413A: Konus-Wind and Swift/BAT joint spectral analysis 
DATE:    15/04/23 10:46:32 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC), D. Palmer (LANL), M.
Stamatikos (OSU) and T. Ukwatta (GWU), report:

We performed the Konus-Wind and the Swift/BAT joint spectral analysis of
GRB 150413A
(Swift/BAT trigger #637899: Markwardt et al., GCN Circ. 17688; Stamatikos
et al., GCN Circ. 17701).
Since the Konus-Wind observed this GRB in the waiting mode, we only have 3
channel spectral data for
the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV.

The joint spectral analysis of the Konus-Wind and the Swift/BAT data
allows us
to derive the broad-band spectral parameters of this burst.

The time intervals of the spectral data for each instrument are chosen
from T0(BAT)-102.150 s to T0(BAT)+159.866 s (the time-integrated spectrum)
and from T0(BAT)+95.098 s to T0(BAT)+118.650 s (the spectrum of the most
prominent pulse)
where T0(BAT) is the trigger time of BAT at 13:54:58 UTC.

The energy ranges which we used in the joint spectral analysis are 20-1200
keV and 15-150 keV
for the Konus-Wind and the Swift/BAT respectively.  The spectral data of
two instruments
are fitted with the spectral model multiplied by the constant factor to
take into account
the systematic effective area uncertainties in the response matrices of
each instrument.

The spectrum of the most prominent pulse is well fitted with
a power-law with exponential cutoff model: dN/dE ~
E^{alpha}*exp(-(2+alpha)*E/Epeak).
No systematic residual from the best fit model is seen in the spectral
data of each instrument.

The BAT constant factor is  0.71(-0.12,+0.16) (the KW constant factor is
fixed to 1).
The best fit spectral parameters are:
alpha = -1.01(-0.44,+0.65), and
Epeak = 96(-22,+56) keV (chi2/dof = 60/57).

The best fit spectral parameters for the GRB (Band) model fixing beta =
-2.5 are:
alpha =  -1.00(-0.51,+0.84), and
Epeak = 91(-26,+77) keV
(chi2/dof = 63/57).

The time-integrated spectrum is well fitted with a power-law model
with the the photon index 1.77(-0.09,+0.09), chi2/dof = 68/58.
The BAT constant factor is  0.70(-0.09,+0.11) (the KW constant factor is
fixed to 1).
The energy fluence in the 15-1200 keV band calculated by a power-law model
for this 262.016 s interval is 1.42(-0.19,+0.20)x10^-5 erg/cm2.

Assuming a redshift of 3.139 (de Ugarte Postigo and Tomasella, GCN Circ.
17710)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
Omega_Lambda = 0.685,
the isotropic energy release in the 1 keV - 10 MeV energy range is
E_iso = 6.53(-1.29,+1.62)x10^53 erg.

All the quoted errors are at the 90% confidence level.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150413A/


GRB_name: GRB150423A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17732
SUBJECT: GRB 150423A: GROND afterglow candidate
DATE:    15/04/23 13:27:32 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

K. Varela, F. Knust, and J. Greiner (all MPE Garching)
report on behalf of the GROND team:

Further to Varela et al. (GCN #17729), we report continued observations 
of the field of GRB 150423A (Swift trigger 638808; Pagani et al., GCN #17728) 
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) 
mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). The 
observations were performed at an average seeing of 1.0 and at an average 
airmass of 1.5.

We detect 2 faint sources within or close to the 2.2" XRT error circle:

Source #1, within the XRT error circle:
 RA (2000.0)   =  14h 46m 18.86s
 Decl (2000.0) = +12d 17' 00.7"
with an error of 0.3".

Source #2, just outside the XRT error circle:
 RA (2000.0)   =  14h 46m 19.04s
 Decl (2000.0) = +12d 17' 03.4
with an error of 0.3". This source matches an object visible in the SDSS.

Based on 25.1 min of total exposure time in g'r'i'z' and 20.0 min in JHK, 
centered 58 min after the GRB, we estimate the following preliminary magnitudes 
(all in AB system).

Source #1:
g' = 23.2 +/- 0.2 mag,
r' = 23.1 +/- 0.2 mag,
i' = 22.8 +/- 0.2 mag,
z' = 22.6 +/- 0.2 mag,
J  > 21.6 mag,
H  > 21.0 mag, and
Ks > 18.5 mag,

Source #2:
g' = 24.2 +/- 0.2 mag,
r' = 23.3 +/- 0.2 mag,
i' = 23.4 +/- 0.3 mag,
z' = 22.9 +/- 0.2 mag,
J  > 21.6 mag,
H  > 21.0 mag, and
Ks > 18.5 mag.

The spectral energy distribution of source #1 is best fit with a 
power-law of slope beta = 0.8+-0.3 (without significant dust extinction), 
typical for GRB afterglows. Also, source #1 is brighter than source #2,
but not visible in the SDSS. While we cannot establish clear fading, we 
suggest this object as the afterglow of GRB 150423A.

Given magnitudes are calibrated against SDSS (g'r'i'z') as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.03 mag in the
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17733
SUBJECT: GRB 150423A: Keck optical afterglow confirmation
DATE:    15/04/23 14:34:27 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports:

I acquired observations of the optical afterglow candidate of GRB 
150423A (Pagani et al., GCN 17726; Varela et al., GCN 17732) using the 
Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m telescope.

Two epochs of V- and i-band imaging were acquired, the first beginning 
at UT 07:13 (approximately 0.75 hours after the trigger, as soon as the 
target cleared the telescope Nasmyth limit), the second beginning at UT 
13:12 (approximately 6.75 hours after the trigger).

The sources mentioned by Varela et al. are well-detected in both epochs. 
  Source 2 remains constant between the frames, while Source 1 declines 
by approximately 0.9 magnitude in both V- and i-band, confirming that it 
is the optical afterglow.

Shortly after the second imaging epoch, I also acquired 1600 seconds of 
low-resolution spectroscopy with the slit oriented to cover both S1 and 
S2.  A faint trace is detected for both sources.  Source 2 shows a clear 
emission line in the blue arm and at least one marginal emission line in 
the red arm, indicating a low to moderate redshift.  Source 1 (the 
afterglow) shows no clear features in emission or absorption, but the 
signal is very weak.  Further analysis will reported at a later time 
pending wavelength calibration of the spectra.


GRB_name: GRB150422A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17734
SUBJECT: GRB 150422A: Fermi GBM detection
DATE:    15/04/23 14:35:44 GMT
FROM:    George A. Younes at USRA/NASA/MSFC  <younes.ge@gmail.com>

George Younes (USRA at GWU) and Charles Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 16:52:33.99  on April 22 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150422A (trigger 451414356/150422703).
The GBM on-ground location, using the Fermi GBM trigger
data, is RA = 215.1, Dec = -20.9 (J2000 degrees, equivalent to
14h 20m 24s, -20d 54), with an uncertainty of 1.1
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 of the burst direction to the Fermi LAT boresight is
57 degrees.

The trigger resulted in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location.

The GBM light curve consists of multiple peaks with a duration
(T90) of about 37 s (50-300 keV).
The time-averaged spectrum from T0+0s to T0+49.2s
is well fit by a BAND function with Epeak = 100 +/- 3 keV,
Alpha = -1.16 +/- 0.03 and Beta = -2.35 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is
(3.40 +/- 0.04)E-05 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+11.6 s in the 10-1000 keV band
is 17.0 +/- 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: GRB150423A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17735
SUBJECT: GRB 150423A: Enhanced Swift-XRT position
DATE:    15/04/23 15:48:49 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 2017 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 150423A, 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 = 221.57899, +12.28349 which is equivalent
to:

RA (J2000): 14h 46m 18.96s
Dec (J2000): +12d 17' 00.6"

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: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17736
SUBJECT: GRB 150423A: RATIR optical afterglow monitoring
DATE:    15/04/23 17:47:09 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Owen Littlejohns (ASU), 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 (ORAU/GSFC), Eleonora Troja
(GSFC), 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 150423A (Pagani, et al., GCN 17728) 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 2015/04 23.41 to 2015/04
23.48 UTC (3.30 to 5.01 hours after the BAT trigger), obtaining a
total of 1.42 hours exposure in the r, i and z bands.

For a source within the Swift-XRT error circle (Evans, et al., GCN
17735), in comparison with the SDSS DR9, we obtain the following
detections and upper limits (3-sigma):

  r     23.77 +/- 0.23
  i     23.62 +/- 0.26
  z     > 20.33

These magnitudes are in the AB system and are not corrected for
Galactic extinction in the direction of the GRB. Of the two sources
reported by GROND (Varela, et al., GCN 17732), this source is at the
position of source 1. Our observations show a fading of 0.8 magnitudes
in the i band, implying a power-law decay with a temporal index,
t^-0.5. Similarly to the Keck observations (Perley, GCN 17733), we
also find source 2 reported by GROND to have remained at approximately
constant brightness.

Continued observations are planned.

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


GRB_name: GRB150423A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17737
SUBJECT: GRB 150423A: Swift-XRT refined Analysis
DATE:    15/04/23 19:06:53 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 8.1 ks of XRT data for GRB 150423A (Pagani et al. GCN
Circ. 17728), from 78 s to 28.7 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Evans et al. (GCN Circ. 17735).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.86 (+/-0.09).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.53 (+0.32, -0.21). The
best-fitting absorption column is  2.9 (+10.0, -1.2) x 10^20 cm^-2,
consistent with the Galactic value of 1.8 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 4.2 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.9 (+10.0, -1.2) x 10^20 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.53 (+0.32, -0.21)

If the light curve continues to decay with a power-law decay index of
0.86, the count rate at T+24 hours will be 1.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.0 x
10^-14 (6.2 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/00638808.

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


GRB_name: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17738
SUBJECT: GRB 150423A: VLT detection
DATE:    15/04/23 20:20:49 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann (TLS Tautenburg), T. Kruehler (ESO Chile), S. Klose (TLS
Tautenburg) and J. Greiner (MPE Garching) report:

We obtained a photometry sequence in BVRIz with VLT FORS2 of the optical 
afterglow (Varela et al., GCN # 17729, # 17732; Perley, GCN # 17733;
Littlejohns et al., GCN # 17736) of the short GRB 150423A (Swift-638808,
Pagani et al., GCN # 17728).

Observations started on April 23, 2015, 08:02:19 UT, 94 minutes after the
GRB. Seeing was 1".0 and airmass was 1.7.

The afterglow is clearly detected in BVR. Analysis of Iz is pending.

We find Rc = 22.8 +/- 0.1 in the first image (calibrated against SDSS
standard stars transformed to Rc) and find it fades by approximately 0.4
magnitudes in the course of an hour (see also Perley, GCN # 17733;
Littlejohns et al., GCN # 17736).

We are indebted to Jonathan Smoker and Fernando Selman for VLT UT1 support.


GRB_name: GRB150423A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17739
SUBJECT: GRB 150423A: Swift/UVOT Upper Limits
DATE:    15/04/23 21:00:00 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F.E. Marshall (NASA/GSFC) and C. Pagani (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150423A
74 s after the BAT trigger (Pagani et al., GCN Circ. 17728).
No optical afterglow consistent with the optical position
(Source 1 in Varela et al. GCN Circ. 17732; Perley GCN Circ. 17733) 
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) exposures and subsequent exposures are:

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

white_FC            74          223          147         >20.8
u_FC               286          535          246         >20.2
white               74         6067          733         >21.5
v                  615         6477          452         >20.9
b                  541         5862          255         >20.9
u                  286         6924          513         >20.8
w1                 665         6887          452         >20.9
m2                5048         6682          393         >20.8
w2                 591         6273          432         >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: GRB150423A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17740
SUBJECT: GRB 150423A: Swift-BAT refined analysis
DATE:    15/04/23 22:07:16 GMT
FROM:    Tilan Ukwatta at LANL  <tilan.ukwatta@gmail.com>

T. N. Ukwatta (LANL), 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 (GSFC/UMBC), C. B. Markwardt (GSFC),
C. Pagani (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 150423A (trigger #638808)
(Pagani, et al., GCN Circ. 17728). The BAT ground-calculated position is
RA, Dec = 221.601, 12.264 deg which is
   RA(J2000)  =  14h 46m 24.2s
   Dec(J2000) = +12d 15' 50.6"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

BAT light curve shows a single peak starting around T+0.0 sec
and ending around T+0.25 sec. T90 (15-350 keV) is 0.22 +- 0.03 sec
(estimated error including systematics).

The time-averaged spectrum from T+0.01 to T+0.24 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
0.84 +- 0.24.  The fluence in the 15-150 keV band is 6.3 +- 1.0 x 10^-08
erg/cm2.
The 1-sec peak photon flux measured from T-0.37 sec in the 15-150 keV band
is 0.9 +- 0.1 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/638808/BA/


GRB_name: GRB150423A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17741
SUBJECT: GRB 150423A: UKIRT NIR observations
DATE:    15/04/24 02:53:39 GMT
FROM:    Wen-fai Fong at U of Arizona  <wfong@email.arizona.edu>

W. Fong and P. Milne (University of Arizona) report on behalf of a larger
collaboration:

"We observed the field of the Swift short-duration GRB 150423A (Pagani et
al., GCN 17728) with UFTI mounted on the 3.8-m United Kingdom Infrared
Telescope (UKIRT) on Mauna Kea beginning on 2015 April 23.337 UT, at an
average airmass of 1.1 in 0.55" seeing. We obtained 6600 sec of J-band
imaging at a mid-time of 2.72 hr post-burst, and 6300 sec of K-band imaging
at a mid-time of 4.93 hr post-burst. The afterglow (Source 1; Varela et
al., GCN 17732; Perley, GCN 17733; Littlejohns et al., GCN 17736; Kann et
al., GCN 17738) is weakly detected in both the J- and K-bands. We cannot
establish fading over the course of our observations due to the weak
detection of the source. We note that Source 2 (Varela et al., GCN 17732)
is only detected in K-band.

Further observations are planned."


GRB_name: GRB150423A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17742
SUBJECT: GRB 150423A: MITSuME Okayama upper limits
DATE:    15/04/24 06:46:33 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 150423A (Pagani et al., GCNC 17728)
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 2015-04-23 17:04:40 UT, (~10.6 h after the burst).
We could not detect the previously reported afterglow (Varela et al., GCNC
17729,17732; Perley, GCNC 17233) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.49107    18:15:13    7200.0   >20.8  >20.8  >19.9
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB150424A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17743
SUBJECT: GRB 150424A: Swift detection of a short burst
DATE:    15/04/24 07:58:55 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. P. Beardmore (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL) and T. N. Ukwatta (LANL) report on behalf of the
Swift Team:

At 07:42:57 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150424A (trigger=638946).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 152.312, -26.647 which is 
   RA(J2000) = 10h 09m 15s
   Dec(J2000) = -26d 38' 47"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single
structure with a duration of about 0.5 sec.  The peak count rate
was ~55000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 07:44:24.7 UT, 87.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
152.3061, -26.6310 which is equivalent to:
   RA(J2000)  = 10h 09m 13.46s
   Dec(J2000) = -26d 37' 51.6"
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This
location is 60 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 (6.03 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.8
(+3.00/-2.59) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 2.87e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 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
0.06. 

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.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: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17744
SUBJECT: GRB 150423A: Keck redshift of neighboring galaxy
DATE:    15/04/24 09:15:25 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) reports:

Further to GCN 17733, I report analysis of the spectroscopy acquired of 
  S2, the neighboring object located 4.0 arcseconds northeast of the 
optical afterglow of GRB 150423A, first announced by Varela et al. (GCN 
17732).

The spectrum of this object shows weak emission lines from OII (3727), 
OIII (5007), Halpha (6563), and marginally Hbeta (4861), all at a common 
redshift of z=0.456.  No features are visible in the trace of S1 at any 
of the same wavelengths (or elsewhere in its spectrum).

At this redshift, the offset between the sources corresponds to 23 kpc 
in projection.

Further observations of S1 will be necessary to determine whether it is 
entirely afterglow or if it also contains flux from a (coincident) host 
galaxy, perhaps at a different redshift.


GRB_name: GRB150424A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17745
SUBJECT: GRB 150424A: Keck detection of optical afterglow
DATE:    15/04/24 10:19:56 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (Caltech) and N. J. McConnell (IfA) report:

We observed the field of short-duration GRB 150424A (Beardmore et al., 
GCN 17743) with the Low Resolution Imaging Spectrometer (LRIS) on the 
Keck I 10m telescope.  Three 120-second imaging exposures in g- and 
R-bands were acquired between 09:15 and 09:26 UT (approximately 1.6 
hours after the GRB trigger), at low elevation through moderate cloud cover.

In both filters we detect a bright (R~20 mag) source, not visible in 
DSS, at the following location inside the XRT error circle:

  RA = 10:09:13.381
dec = -26:37:51.50
(+/- 0.5" or less)

We suggest this as the optical afterglow of GRB 150424A.

We also note the presence of a large galaxy (resolved in DSS) 5 arcsec 
to the southwest.


GRB_name: GRB150424B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17746
SUBJECT: GRB 150424B: MAXI/GSC detection
DATE:    15/04/24 10:48:10 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

Y. Ono (Tokyo Tech), S. Nakahira (JAXA), T. Masumitsu, H. Negoro  (Nihon U.), 
S. Ueno, H. Tomida,  M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
M. Nakajima,  T. Namba, M. Fujita, F. Honda, K. Tanaka (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, S. Kanetou (Chuo U.),
M. Yamauchi, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.),
M. Morii (ISM)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 
09:40:14 UT.

Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (182.759 deg, -16.212 deg) = (12 11 02, -16 12 43) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.13 deg and 0.11 deg, respectively. 
The roll angle of long axis from the north direction is 23.0 deg counterclockwise. 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(182.383 deg, -15.974 deg) = (12 09 31, -15 58 27) (J2000)
(182.575 deg, -15.799 deg) = (12 10 18, -15 47 55) (J2000)
(182.974 deg, -16.261 deg) = (12 11 53, -16 15 40) (J2000)
(182.781 deg, -16.436 deg) = (12 11 07, -16 26 10) (J2000)

The X-ray flux averaged over the scan was 544 +- 53 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at 08:07 UT
with an upper limit of 20 mCrab.


GRB_name: GRB150423A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17747
SUBJECT: GRB 150423A: WHT observations
DATE:    15/04/24 11:35:37 GMT
FROM:    Klaas Wiersema at U Leicester  <kw113@leicester.ac.uk>

K. Wiersema (Leicester), A. Levan (Warwick), N. Tanvir (Leicester), C. MacLeod
(IfA Edinburgh), F. Riddick (ING) report:

We observed the position of GRB 150423A (Pagani et al. GCN 17728) using the
ACAM instrument on the William Herschel Telescope, at La Palma. We obtained
images with 5 x 300 sec exposure time in both sloan g and z bands, starting at 
22:30 UT on 23 April 2015. The nearby galaxy (Varela et al. GCN 17732; Perley et
al. GCN 17744) is clearly detected, but the afterglow (Varela et al. GCN 17732)
is not significantly detected, with a 5 sigma limit of g~25.3 (calibrated using
SDSS field objects). A low significance object may be present near the afterglow
position in g band, as well as some faint galaxies, which may be candidate hosts.
See here for an image of the field:
http://www2.le.ac.uk/departments/physics/people/klaaswiersema/wht-observations-of-grb-150423a/view


GRB_name: GRB150424B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17748
SUBJECT: GRB 150424B: Tiled Swift observations
DATE:    15/04/24 13:50:16 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 150424B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00042

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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


GRB_name: GRB150424A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17749
SUBJECT: GRB 150424A: Enhanced Swift-XRT position
DATE:    15/04/24 14:17:39 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 3164 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 150424A, 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 = 152.30569, -26.63092 which is equivalent
to:

RA (J2000): 10h 09m 13.37s
Dec (J2000): -26d 37' 51.3"

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: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17750
SUBJECT: GRB 150423A: TSHAO optical observations
DATE:    15/04/24 14:37:06 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Volnova (IKI), A. Kusakin (Fesenkov Astrophysical 
Institute),  A. Pozanenko  (IKI) report on behalf of larger GRB follow-up 
collaboration:

We observed the field of GRB 150423A (Pagani et al., GCNC 17728) with 
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory 
starting on Apr. 23 (UT) 17:43:02.  We obtained several  images in R-filter. 
In a combined image we marginally detect the source S2 and do not detect the 
afterglow (Varela et al., GCN 17729). Coordinates of the S2  (J2000) 14 46 
18.94  +12 17 04.4  with an uncertainty of  0.4" is marginally coincide with 
coordinates reported by Varela et al.  (GCN 17729).

A preliminary photometry is following

date              UT start    t-T0         Filter  Exp.        S1       S2 
S2_err
                                      (mid, days)        (s)

2015-04-23 17:43:02  0.57561  R       25*600  >22.7   22.7   0.3


and based on nearby SDSS DR9 stars:

 SDSS9_id R(Lupton)
 J144606.22+121513.3 15.42
 J144647.40+121502.9 17.54
 J144648.52+121523.3 15.15


GRB_name: GRB150424A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17751
SUBJECT: GRB 150424A: Swift/UVOT Observations
DATE:    15/04/24 15:03:18 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150424A
99 s after the BAT trigger (Beardmore et al., GCN Circ. 17743).
A source consistent with the position
of the suggested optical afterglow
(Perley and McConnell, GCN Circ. 17745)
is detected in the initial UVOT exposures.
The source remains nearly constant in 6 exposures with the 
white filter starting 99 s after the trigger and ending
6786 s after the trigger. The magnitude is approximately that
reported by Perley and McConnell. This may be a detection
of the host galaxy.

The preliminary UVOT position is:
   RA  (J2000) =  10:09:13.38 = 152.30577 (deg.)
   Dec (J2000) = -26:37:51.1  = -26.63086 (deg.)
with an estimated uncertainty of 0.6 arcsec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limit 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               99         6786          609         20.38 +/- 0.07
v                  641         5881          432        >19.8
b                  567         6701          432         20.71 +/- 0.21
u                  311         5061          462         20.13 +/- 0.20
w1                 690         6291          413         20.00 +/- 0.24
m2                4452         6086          393         19.91 +/- 0.29
w2                 616         5677          216         20.03 +/- 0.31

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).

[GCN OPS NOTE(24apr15): Per author's request the missing minus sign
on the hh:mm:ss format of the value was added; the decimal-deg value was correct.]


GRB_name: GRB150424A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17752
SUBJECT: Konus-Wind observation of GRB 150424A
DATE:    15/04/24 16:56:48 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short-duration, intense GRB 150424A
(Swift/BAT detection: Beardmore et al., GCN Circ. 17743).
triggered Konus-Wind at T0=27781.073 s UT (07:43:01.073).

The burst light curve shows a multipeak structure
with a total duration of ~0.4 s.
The emission is seen up to 4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150424_T27781/

As observed by Konus-Wind, the burst
had a fluence of 1.81(-0.11,+0.11)x10^-5 erg/cm2,
and a 2-ms peak flux, measured from T0+0.212 s,
of 1.85(-0.48,+0.48)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.37(-0.09,+0.10)
and Ep = 919(-76,+82) keV (chi2 = 66/57 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.8
(chi2 = 66/56 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB150424B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17753
SUBJECT: GRB 150424B: Fermi GBM detection
DATE:    15/04/24 18:34:27 GMT
FROM:    Binbin Zhang at UAH  <binbin.zhang@uah.edu>

Bin-Bin Zhang (UAH) and A. von Kienlin (MPE) reports on behalf of the
Fermi GBM Team:

"At 09:39:59.68 UT on 24 April 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150424B (trigger 451561202 / 150424403),
which was also detected by the MAXI/GSC (Ono et al. 2015, GCN 17746).
The GBM on-ground location is consistent with the MAXI/GSC position.
The angle from the Fermi LAT boresight is about 107 degrees.

The GBM light curve shows a single pulse with a duration (T90)
of about 36.1 s (50-300 keV). The time-averaged spectrum from
T0-8 s to T0+28 s is best fit by a Band function with
Epeak = 56.6 +/- 8.1 keV, alpha = -0.8 +/- 0.3, and beta = -2.4 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(3.85 +/- 0.31)E-06 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0-0.4 s in the 10-1000 keV band
is 3.8 +/- 0.3 ph/s/cm^2.

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


GRB_name: GRB150423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17754
SUBJECT: GRB 150423A: Continued RATIR optical afterglow monitoring
DATE:    15/04/24 19:01:43 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Owen Littlejohns (ASU), 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 (ORAU/GSFC), Eleonora Troja
(GSFC), 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 150423A (Pagani, et al., GCN 17728)
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 2015/04 24.18 to 2015/04 24.48
UTC (21.74 to 28.97 hours after the BAT trigger), obtaining a total of
5.69 hours exposure in the r, i and z bands.

For a source within the Swift-XRT error circle (Evans, et al., GCN
17735), in comparison with the SDSS DR9, we obtain the following upper
limits (3-sigma):

  r     > 24.82
  i     > 24.79
  z     > 22.07

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. In comparison to the earlier
epoch of RATIR observations (Littlejohns, et al., GCN 17736), these upper
limits indicate fading of at least 1 magnitude in the r and i bands. This
implies a continuing power-law decay temporal power-law index of t^-0.5
or steeper, which is consistent with the comparison between the first
epoch of RATIR observations and the earlier GROND measurements (Varela,
et al., GCN 17732). The magnitude of source 2, as reported in the GROND
observations, is consistent with being constant in both epochs of RATIR
data.

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


GRB_name: GRB150423A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17755
SUBJECT: GRB 150423A: VLT/X-shooter spectroscopy and tentative redshift
DATE:    15/04/24 22:10:20 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Malesani (DARK/NBI), T. Kruehler (ESO), D. Xu (NAOC/CAS), G. Pugliese (API/Uva), D. Watson, J. P. U. Fynbo, B. Milvang-Jensen (DARK/NBI), A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), N. R. Tanvir (U. Leicester), V. D'Elia (ASI/ASDC and INAF/Roma), K. Wiersema (U. Leicester),  J. Greiner(MPE Garching), J. Japelj (U. Ljubljana) report on behalf of a larger collaboration:

We observed the optical afterglow (Varela et al., GCNs 17729, 17732, Perley, GCN 17733, Littlejohns et al. GCN 17736, Kann et al. GCN 17738, Fong & Milne GCN 17741) of the Swift short-GRB 150423A (Pagani et al. GCN 17728) with the VLT equipped with the X-shooter spectrograph in the rapid response mode (RRM).

A series of individual spectra with a total exposure time of around 5000 s were obtained starting on 2015-04-23 06:50 UT, which is 22 minutes after the BAT trigger.

A preliminary analysis of the spectrum reveals a faint and blue continuum detected down to 3200 AA. This sets a robust upper limit of z < 2.5 to the redshift of the GRB. Similarly to Perley (GCNs 17733, 17744), we do not detect obvious absorption or emission features in our spectra. There is, however, a tentative detection of a doublet in absorption at around 6900 AA. If real, the lines match the Mg II doublet at a redshift of z = 1.394.

We acknowledge the excellent support provided by Paranal staff, and in particular Fernando Selman and Emanuela Pompei.


GRB_name: GRB150424A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17756
SUBJECT: GRB 150424A: NOT optical observations
DATE:    15/04/24 23:08:53 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), D. Xu (NAOC/CAS), D. J. Watson (DARK/NBI), and 
P. Blay (IAC/NOT), report on behalf of a larger collaboration:

We observed the optical counterpart (Perley, GCN 17745; Marshall & 
Beardmore, GCN 17751) of the short GRB 150424A (Beardmore et al., GCN 
Circ. 17743), using the Nordic Optical Telescope equipped with the 
AlFOSC camera. The first 300-s R-band exposure was taken starting at 
20:57 UT (13.2 hr after the GRB)

We clearly detect the counterpart with a magnitude R = 20.67 +- 0.06 
(assuming R = 16.27 for the USNO star at RA = 10:09:11.09, Dec = 
-26:36:58.4).

This magnitude is just slightly fainter than the value reported by 
Perley (GCN 17745) 1.6 hr after the trigger, indicating a very slow 
decay - consistent with the UVOT report. The brightness of the afterglow 
is unprecedented for a short GRB this late after the GRB. Such a 
behaviour is unusual and we encourage further observations.


GRB_name: GRB150424A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17757
SUBJECT: GRB 150424A: GROND detects strong fading
DATE:    15/04/24 23:55:22 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

D. A. Kann (TLS Tautenburg), M. Tanga, and J. Greiner (both MPE Garching)
report on behalf of the GROND team:

We observed the field of the extremely bright short GRB 150424A (Swift
trigger 638946; Beardmore et al., GCN #17743) simultaneously in
g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the
2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations started at 23:09 UT on 2015-04-24, 15.4 hrs after the GRB
trigger. They were performed at an average seeing of 1".2 and at an
average airmass of 1.1.

We detect the optical afterglow (Perley & McConnell, GCN # 17745; Malesani
et al., GCN # 17756).

Based on 7.7 min of total exposure time in g'r'i'z' and 8.0 min in JHK,
centered 15.54 hrs after the GRB, we estimate the following preliminary
magnitudes (all in AB system):

g' = 22.0 +/- 0.2 mag,
r' = 21.6 +/- 0.1 mag,
i' = 21.4 +/- 0.1 mag,
z' = 21.1 +/- 0.1 mag,
J  = 20.4 +/- 0.5 mag, and
H  > 19.9  mag.

Compared to the NOT detection about two hours earlier, the afterglow has
faded by 0.7 magnitudes, indicating the transition to a very rapid decay.

Given magnitudes are calibrated against GROND zero points (g'r'i'z') as
well as 2MASS field stars and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.06 mag in
the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB150424A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17758
SUBJECT: GRB 150424A: 10.4m GTC spectroscopy 
DATE:    15/04/25 01:34:57 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

A. J. Castro-Tirado (IAA-CSIC, ISA-UMA), R. Sanchez-Ramirez (UPV/EHU,
IAA-CSIC), G. Lombardi (IAC, ULL, GRANTECAN) and M. A. Rivero (GRANTECAN),
on behalf of a larger collaboration, report:

Following the detection of the short-duration GRB 150424A by Swift/BAT
(Beardmore et al. 2015, GCNC 17743) and Konus-Wind (Golenetskii et al.
GCNC 17752), we have obtained an optical spectrum (2 x 900s) with the
10.4m GTC telescope (+OSIRIS) in La Palma (Spain), starting on Apr 24,
21:30 UT (i.e. 13.8 hr postburst), covering the 3700-10000 wavelength
range. The slit included the position of the proposed optical afterglow
(Perley and McConnell, GCNC 17745; Marshall and Beardmore, GCNC 17751;
Malesani et al., GCNC 17756; Kann et al. GCNC 17757) as well as the
extended galaxy 5 arcsec to the southwest (Perley and McConnell GCNC
17745).

At the position of the optical afterglow, we see no obvious absorption
features with the continuum extending to 3700 A (implying an upper limit
of z < 3 to the redshift of the GRB). At the position of the nearby
galaxy, we detect [O II] and H-alpha in emission at a redshift z = 0.30.
At this redshift, 5 arcsec corresponds to 22.5 kpc. A more detailed data
reduction is ongoing.

We acknowledge D. Perley for providing the corresponding ID-chart.


GRB_name: GRB150424A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17759
SUBJECT: GRB 150424A: spectral lag, extended-time emission
DATE:    15/04/25 01:52:26 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. P. Norris (BSU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
and N. Gehrels (GSFC) report:

We report spectral lag and extended emission measurements for the intense,
short GRB 150424A (trigger=638946; GCN Circ. 17743, 17745 & 17756) based
on Swift-BAT data.

Using a 4-ms binned light curve, the lag for the 25-50 keV to 100-350 keV bands
is estimated as 0.6 (+0.6/-1.0) ms; and -2.4 (+1.3/-0.7) ms for the 15-25 keV
to 50-100 keV bands.

A Bayesian Block analysis of the mask-tagged data reveals one significant
block of duration ~ 106 seconds at a level of 0.006 counts/det/s, following
the intense, initial pulse complex.  This extended emission component is
three orders of magnitude lower than the peak intensity of the burst,
~ 5.3 counts/pixel/s.


GRB_name: GRB150424A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17760
SUBJECT: GRB 150424A: Swift-XRT refined Analysis
DATE:    15/04/25 07:59:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N.
Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), P.A.
Evans (U. Leicester), A. Amaral-Rogers (U. Leicester) and A.P.
Beardmore report on behalf of the Swift-XRT team:

We have analysed 5.1 ks of XRT data for GRB 150424A (Beardmore et al.
GCN Circ. 17743), from 77 s to 29.7 ks after the  BAT trigger. The data
comprise 206 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 Goad et al.
(GCN Circ. 17749).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.22 (+0.13, -0.29). At T+168 s  the decay
steepens to an alpha of 2.75 (+0.14, -0.19) before breaking again at
T+676 s to a final decay with index alpha=0.64 (+0.08, -0.10).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.60 (+/-0.07). The
best-fitting absorption column is  9.4 (+2.7, -2.5) x 10^20 cm^-2, in
excess of the Galactic value of 6.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.00 (+0.19, -0.18)
and a best-fitting absorption column of 1.1 (+0.6, -0.5) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.3 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.1 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 6.0 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index:      2.00 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
0.64, the count rate at T+24 hours will be 0.022 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.4 x
10^-13 (9.2 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/00638946.

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


GRB_name: GRB150424A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17761
SUBJECT: GRB 150424A: Swift-BAT refined analysis
DATE:    15/04/25 15:46:23 GMT
FROM:    Tilan Ukwatta at LANL  <tilan.ukwatta@gmail.com>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent
telemetry downlink, we report further analysis of BAT
GRB 150424A (trigger #638946) (Beardmore, et al., GCN Circ. 17743).
The BAT ground-calculated position is RA, Dec = 152.305, -26.646 deg
which is
   RA(J2000)  =  10h 09m 13.2s
   Dec(J2000) = -26d 38' 45.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 69%.

BAT light curve shows a bright multi-peaked episode starting
around T-0.05 sec, and ending around T+0.5 sec. Very weak
extended emission can be seen up to about T+100 sec as mentioned
in Norris, et al., GCN Circ. 17759. T90 (15-350 keV) is
91 +- 22 sec (estimated error including systematics).

The time-averaged spectrum from T-0.06 to T+106.32 sec is best fit by a
simple power-law model.  The power law index of the time-averaged
spectrum is 1.23 +- 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-0.06 sec in the 15-150 keV band is 12.0 +- 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/638946/BA/


GRB_name: GRB150424A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17762
SUBJECT: GRB 150424A: RATIR Observations
DATE:    15/04/25 17:26:07 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
(ORAU/GSFC), 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 the short-duration GRB 150424A (Beardmore, et al.,
GCN 17743) 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 2015/04 25.14 to 2015/04
25.28 UTC (19.54 to 23.05 hours after the BAT trigger), obtaining a total
of 2.4 hours exposure in the r, i, and z bands.

The optical afterglow (Perley, GCN 17745; Marshall & Beardmore, GCN 17751;
Malesani, et al., GCN 17756; Kann, et al., GCN 17757) is well-detected.  In
comparison with 2MASS and the USNO-B1 catalog, we obtain the following
detections and upper limit (3-sigma):

  r     21.92 +/- 0.11
  i     21.65 +/- 0.09
  z     > 20.17

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  Compared to the earlier NOT and
GROND observations, the source appears to be continuing its strong fade
(Kann, et al. GCN 17757).

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


GRB_name: GRB150423A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17763
SUBJECT: GRB 150423A: MITSuME Akeno Optical observation
DATE:    15/04/27 05:50:43 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

S.Harita, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano,
S. Kurita, Y.Ono, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)


report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 150423A (C. Pagani et al. GCN Circular #17728) 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 2015-04-23 13:03:48 UT (~6.6 h after the burst).
We did not find any new point source within XRT circle in all three bands.

We obtained following limits for the magnitudes.

T0+[sec]      MID-UT      T-EXP[sec]         g'           Rc           Ic
---------------------------------------------------------------------------------------
  23744     16:26:45          2940           >19.4      >19.3     > 18.4
---------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration


GRB_name: GRB150428A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17765
SUBJECT: GRB 150428A: Swift detection of a burst
DATE:    15/04/28 01:53:52 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K. L. Page (U Leicester), M. M. Chester (PSU), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:

At 01:30:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150428A (trigger=639275).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 188.543, +6.981 which is 
   RA(J2000) = 12h 34m 10s
   Dec(J2000) = +06d 58' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex structure 
with a duration of about 50 sec.  The peak count rate
was ~1700 counts/sec (15-350 keV), at ~17 sec after the trigger. 

The XRT began observing the field at 01:33:36.7 UT, 175.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 188.53889, 6.95211 which is equivalent
to:
   RA(J2000)  = 12h 34m 09.33s
   Dec(J2000) = +06d 57' 07.6"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 105 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 (1.63 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 9.3
(+6.64/-5.03) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 179 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 none of
the XRT error circle. 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 0.02. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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: GRB150428B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17766
SUBJECT: GRB 150428B: Swift detection of a burst
DATE:    15/04/28 03:37:48 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K. L. Page (U Leicester), M. M. Chester (PSU),
F. E. Marshall (NASA/GSFC), T. Sakamoto (AGU) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 03:12:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150428B (trigger=639278).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 292.654, +4.116 which is 
   RA(J2000) = 19h 30m 37s
   Dec(J2000) = +04d 06' 57"
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 30 sec.  The peak count rate
was ~1800 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 03:13:50.9 UT, 107.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 292.63764, 4.12529
which is equivalent to:
   RA(J2000)  = 19h 30m 33.03s
   Dec(J2000) = +04d 07' 31.0"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 67 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 consistent with the Galactic value of 3.26
x 10^21 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 8.91e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 117 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. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. Because of the density of catalogued stars,
further analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.40. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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: GRB150428A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17767
SUBJECT: GRB 150428A: GROND Dark Burst Host Candidate
DATE:    15/04/28 04:15:54 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

F. Knust (MPE Garching), D. A. Kann (TLS Tautenburg), T. Kruehler (ESO),
and J. Greiner (MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 150428A (Swift trigger 639275; Page et al.,
GCN #17765) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 02:24 UT on 2015-04-28, 53 minutes after the GRB
trigger, following a delay due to the labeling of the event as "not a GRB"
in the BACODINEs. They were performed at an average seeing of 0".9 and at
an average airmass of 1.2.

We detect a source at (J2000):

RA =    12:34:09.26
Dec. = +06:57:08.7

with an error of 0".5 in each coordinate.

Based on 25 min of total exposure time in g'r'i'z' centered 1.41 hrs after
the GRB, we estimate the following preliminary magnitudes (all in AB
system):

g' = 24.1 +/- 0.4 mag,
r' = 23.0 +/- 0.1 mag,
i' = 22.7 +/- 0.1 mag, and
z' = 23.2 +/- 0.2 mag.

At this time, we cannot establish fading. At this position, we also detect
a source in the SDSS, which implies that this would be the host galaxy of
this GRB. We note the hydrogen column density as derived from X-rays
(Page et al., GCN #17765) is much higher than the (very low) Galactic NH,
implying this may be an optically dust-suppressed event.

Given magnitudes are calibrated against SDSS field stars and are not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V)=0.02 mag in the direction of the burst (Schlegel et
al. 1998).


GRB_name: GRB150428A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17768
SUBJECT: GRB 150428A: Enhanced Swift-XRT position
DATE:    15/04/28 05:34:00 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 147 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150428A, 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 = 188.53878, +6.95390 which is equivalent
to:

RA (J2000): 12h 34m 9.31s
Dec (J2000): +06d 57' 14.0"

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: GRB150428A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17769
SUBJECT: GRB 150428A: P60 observations
DATE:    15/04/28 06:00:44 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

We observed the field of GRB 150428A (Page et al., GCN 17765) using the 
Palomar 60-inch robotic telescope starting at UT 03:40:50 on the night 
of 2015-04-28, acquiring a sequence of r, i, and z-band exposures under 
excellent seeing conditions.

Stacking a series of 9x180s i-band images between 03:44 and 04:25 UT, we 
detect no sources within the enhanced XRT error circle (Osborne et al., 
GCN 17768) down to a limiting magnitude of i > 22.7 mag at a median time 
of 2.65 hours after the trigger.  We note that the source reported by 
GROND (Knust et al., GCN 17767) is not within the enhanced error circle, 
but we marginally detect this source at a similar magnitude (i = 22.8 
+/- 0.3 mag).


GRB_name: GRB150428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17770
SUBJECT: GRB 150428A: RATIR optical observations
DATE:    15/04/28 06:46:58 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Owen Littlejohns (ASU), 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 (ORAU/GSFC), Eleonora Troja
(GSFC), 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 150428A (Page, et al., GCN 17765) 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 2015/04 28.14 to 2015/04
28.27 UTC (1.80 to 4.88 hours after the BAT trigger), obtaining a
total of 2.49 hours exposure in the r, i and z bands.

We find no uncatalogued source within the Swift-XRT error circle
(Osborne, et al., GCN 17768). In comparison with the SDSS DR9, we
obtain the following upper limits (3-sigma):

  r     > 23.94
  i     > 23.90
  z     > 19.56

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. We note that the source detected
by GROND (Knust, et al., GCN 17767) and P60 (Perley, GCN 17769) is not
consistent with the enhanced X-ray position. For the GROND source, in
comparison with the SDSS DR9, we obtain the following detections and
upper limit (3-sigma):

  r     = 23.41 +/- 0.22
  i     = 22.75 +/- 0.14
  z     > 19.56

The RATIR observations of the GROND source, therefore, do not show
evidence of fading between the GROND and RATIR epochs of observations.
Further RATIR observations are ongoing.

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


GRB_name: GRB150428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17771
SUBJECT: GRB 150428A: Danish1.56m optical observations
DATE:    15/04/28 07:29:12 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

M. I. Andersen (NBI/StarPlan), D. Xu (NAOC/CAS), M. Kuffmeier (StarPlan), and D. Evans (Keele U.) report on behalf of a larger collaboration:

We observed the field of GRB 150428A (Page et al., GCN 17765) using the Danish 1.56m telescope located at La Silla, Chile. Observations started at 01:56:33 UT on 2015-04-28 (i.e., 0.43 hr post-burst) and 12x180s R-band images were obtained.

We marginally detect a source in the stacked image at coordinates

R.A. = 12:34:09.227
Dec. = +6:57:14.07

Error Radius: ~ 1 arcsec,

consistent with the enhanced XRT position (Osborne et al., GCN 17768). Preliminary reduction shows that the source has m(R) = 22.50 +/- 0.43 mag at a median time of 0.887 hr post-burst, calibrated with two nearby SDSS stars. It could be the afterglow of the GRB.

We also detect the source reported by GROND (Knust et al., GCN 17767). It is extended in the northwest-southeast direction. Its position is not consistent with the present enhanced XRT position, as noted by P60 (Perley, GCN 17769).


GRB_name: GRB150428B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  17773
SUBJECT: GRB 150428B: Enhanced Swift-XRT position
DATE:    15/04/28 11:45:22 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 1321 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150428B, 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 = 292.63941, +4.12505 which is equivalent
to:

RA (J2000): 19h 30m 33.46s
Dec (J2000): +04d 07' 30.2"

with an uncertainty of 1.6 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.


