# GCN_circulars

GRB_name: GRB151021A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18433
SUBJECT: Konus-Wind observation of GRB 151021A
DATE:    15/10/21 17:41:03 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration, intense GRB 151021A (Swift-BAT trigger #660671:
Melandri et al., GCN 18425; Krimm et al., GCN 18429)
triggered Konus-Wind at T0=5336.535 s UT (01:28:56.535).

The burst light curve shows a multi-peaked structure
started at ~T0-6.1 s with a total duration of ~100 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB151021_T05336/

As observed by Konus-Wind, the burst
had a fluence of 7.66(-0.87,+0.97)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+22.256 s,
of 4.92(-1.44,+1.41)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+131.328 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.14 (-0.14,+0.15),
the high energy photon index beta = -2.46 (-0.32,+0.18),
the peak energy 170 (-18,+23) keV
(chi2 = 94/96 dof)

The spectrum near the maximum count rate
(measured from T0+16.640 to T0+33.024 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.89 (-0.19,+0.19),
the high energy photon index beta = -2.29 (-0.32,+0.14),
the peak energy 200 (-27,+46) keV
(chi2 = 73/96 dof)

Assuming the redshift z=2.330 (de Ugarte Postigo et al., GCN 18426)
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 ~2.2x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~666 keV.

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


GRB_name: GRB151021B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18434
SUBJECT: GRB 151021B: Fermi GBM detection
DATE:    15/10/22 04:10:01 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

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

"At 18:59:28.92 UT on 21 October 2015, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 151021B (trigger 467146772 /
151021791).

The on-ground calculated location, using the GBM trigger data, is RA =
104.340, DEC = -10.960 (J2000 degrees, equivalent to 06 h 57 m, -10 d
58 '), with an uncertainty of 1.20 degrees (radius, 1-sigma
containment, statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90%
of GRBs having a 3.7 deg error and a small tail suffering a larger
than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32]
).

The angle from the Fermi LAT boresight at the GBM trigger time is 83 degrees.

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

The GBM light curve consists of a single pulse with fast rise and
exponential decay with a duration (T90) of about 7.2 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+9.1 s is well fit by a
power law function with an exponential high-energy cutoff. The power
law index is -0.67 +/- 0.03 and the cutoff energy, parameterized as
Epeak, is 270 +/- 10 keV.

A Band function fits the spectrum equally well with Epeak = 241 +/- 13
keV, alpha = -0.61 +/- 0.04 and beta = -2.6 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is (1.226 +/-
0.004)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+0.77 s in the 10-1000 keV band is 21.5 +/- 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: GRB151021A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18435
SUBJECT: GRB 151021A: MITSuME Okayama Ks-band upper-limit
DATE:    15/10/22 06:19:51 GMT
FROM:    Kenshi Yanagisawa at OAO/NAOJ  <yanagi@oao.nao.ac.jp>

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

We observed the field of GRB 151021A (Melandri et al., GCN 18425)
in Ks-band with a wide-field near infrared imager at Okayama
Astrophysical Observatory (Japan).  The imager has effective
aperture of 0.91 m.

Observations started from 10:42 UT on 21th October, 9.2h after
the BAT trigger, to 11:11 UT. The total exposure of 11.7 min
was successfully obtained.

In our co-add image, we did not find any new point source within
the enhanced XRT error circle (Osborne et al., GCN 18428) down
to limiting magnitude of Ks=14.5 (Vega, S/N=10). The photometric
calibration was made against 2MASS field stars.

T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
 +34,049    10:56      700.0           >14.5
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151022A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18436
SUBJECT: GRB 151022A: Swift detection of a burst
DATE:    15/10/22 14:22:47 GMT
FROM:    David Burrows at PSU/Swift  <burrows@astro.psu.edu>

P. D'Avanzo (INAF-OAB), D. N. Burrows (PSU),
H. A. Krimm (CRESST/GSFC/USRA), A. Melandri (INAF-OAB),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:

At 14:06:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151022A (trigger=661036).  Swift slewed to the burst at 
T0+300 seconds.  The BAT on-board calculated location is 
RA, Dec 349.213, +55.813 which is 
   RA(J2000) = 23h 16m 51s
   Dec(J2000) = +55d 48' 48"
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 20 sec.  The peak count rate
was ~1400 counts/sec (15-350 keV), at ~6 sec after the trigger. 

The XRT began observing the field at 14:11:32.6 UT, 300.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 349.19815, 55.81207 which
is equivalent to:
   RA(J2000)  = 23h 16m 47.56s
   Dec(J2000) = +55d 48' 43.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 30 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 4.74
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 304 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the large, but uncertain extinction expected. 

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


GRB_name: GRB151022A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18437
SUBJECT: GRB 151022A: MASTER-Ural observations
DATE:    15/10/22 14:32:11 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

V. Lipunov, E. Gorbovskoy,   N.Tyurina, V.Kornilov, P.Balanutsa,
A.Kuznetsov, D.Kuvshinov, D. Vlasenko, E.Popova
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


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 Ural was pointed to the  GRB151022A  16 after notice time and 
76 sec after trigger time at 2015-10-22 14:07:48 UT in two polarizations. 
On our first (20s exposure)  set we haven't found optical transient 
within SWIFT error-box (ra=23 16 51 dec=+55 48 47 r=0.05).
The 5-sigma upper limit has been about 16.0 mag
The reduction is continued.
The message may be cited.

[GCN OPS NOTE(23oct15):  The GRB name in the Subject line
was changed from "0922A" to "1022A".]


GRB_name: GRB151022A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18438
SUBJECT: GRB 151022A: Prompt enhanced Swift-XRT position
DATE:    15/10/22 15:04:40 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 151022A, we find an
enhanced XRT position of the afterglow: RA, Dec: 349.1969, 55.8119
which is equivalent to:
   RA (J2000)  = 23 16 47.25
   Dec (J2000) = +55 48 42.9
with an uncertainty of 2.0 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/661036.

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: GRB151022A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18439
SUBJECT: GRB 151022A: Kanata/HOWPol optical observation
DATE:    15/10/22 15:10:33 GMT
FROM:    Koji Kawabata at HASC,Hiroshima U  <kawabtkj@hiroshima-u.ac.jp>

K. S. Kawabata, R. Itoh, T. Nakaoka, M. Yoshida (Hiroshima Univ.), K. Tsumura
(Tohoku Univ.), and K. Arimatsu (NAOJ) report on behalf of Kanata team:

We performed a series of optical imaging-polarimetry for the optical afterglow 
of GRB151022A (D'Avanzo et al., GCN 18436) from 119 sec after the Swift/BAT 
trigger with HOWPol attached to the 1.5-m Kanata telescope at Higashi-Hiroshima
Observatory, Japan.

We could not detect any afterglow within the XRT error circle reported in the 
GCN 18436. We obtained the following preliminary upper limits (3-sigma) in our 
first image (mid-time 134 sec after the trigger) calibrated with UCAC4:

Rc > 17.0

Further analysis is ongoing.


GRB_name: GRB151022A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18440
SUBJECT: GRB 151022A: MITSuME Okayama Ks-band upper-limit
DATE:    15/10/22 15:51:57 GMT
FROM:    Kenshi Yanagisawa at OAO/NAOJ  <yanagi@oao.nao.ac.jp>

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

We observed the field of GRB 151022A (D'Avanzo et al., GCN 18436)
in Ks-band with a wide-field near infrared imager at Okayama
Astrophysical Observatory (Japan).  The imager has effective
aperture of 0.91 m.

Observations started from 14:13 UT on 22th October, 0.12h after
the BAT trigger, to 14:56 UT. The total exposure of 17.0 min
was successfully obtained.

In our co-add image, we did not find any new point source within
the enhanced XRT error circle (Evans et al., GCN 18438) down to limiting
magnitude of Ks=14.8 (Vega, S/N=10). The photometric calibration was
made against 2MASS field stars.

T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
 +1,721     14:35      1,020.0         >14.8
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151022A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18441
SUBJECT: GRB 151022A: Mondy optical upper limit
DATE:    15/10/22 19:35:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of Swift GRB 151022A (D'Avanzo et al., GCN 18436) 
with AZT-33IK telescope of Sayan observatory (Mondy) starting on Oct. 22 
(UT) 15:05:04. We obtained several images in R-filter of 30 s exposure. 
    Within XRT error circle (Evans, GCN 18438)  we do not detect any 
optical source in any single image. Upper limit (3 sigma) of a single 
image is R ~ 19.4m. Photometry is based on nearly USNO-B1.0 (R2) stars.


GRB_name: GRB151022A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18442
SUBJECT: LIGO/Virgo G194575: Identification of a GW CBC Candidate
DATE:    15/10/22 20:03:45 GMT
FROM:    Leo Singer at NASA/GSFC  <leo.p.singer@nasa.gov>

Leo Singer (NASA/GSFC), Peter Shawhan (UMD), Nipuni Palliyaguru (TTU), B.
S. Sathyaprakash (Cardiff), Alex Urban (UWM), Jeff Bartlett (LIGO
Hanford), Travis Sadecki (LIGO Hanford), Mike Landry (LIGO Hanford), Joe
Hanson (LIGO Livingston), Bryan Smith (LIGO Livingston), Brian O'Reilly
(LIGO Livingston), Kipp Cannon (CITA), Gianluca Guidi (Urbino), Andy
Lundgren (AEI/Hannover), Laura Nuttall (Syracuse), T. J. Massinger
(Syracuse), Jessica McIver (Caltech), and Joshua Smith (Fullerton) report
on behalf of the LIGO Scientific Collaboration and Virgo:

The gstlal CBC analysis, which is sensitive to binary coalescence events
from systems containing at least one neutron star, identified candidate
G194575 during real-time processing of data from LIGO Hanford Observatory
(H1) and LIGO Livingston Observatory (L1) at 2015-10-22 13:33:19.942 UTC
(GPS time: 1129556016.942). Both the H1 and L1 detectors were in
observation mode and operating normally.

G194575 is an event of interest because its false alarm rate, as
determined by the online analysis, is 9.65e-08 Hz or about one in 4
months, passing our stated alert threshold of ~1/month for CBC candidates.
The event's properties can be found at this URL:

https://gracedb.ligo.org/events/G194575

Fermi triggered (bn151022577) about 1 ks after the LIGO candidate, and
Swift detected GRB 151022A (Dâ€™Avanzo et al., GCN 18436) about 2 ks after.
Neither gamma-ray triggerâ€™s localization is consistent with the rapid
position reconstruction of the LIGO candidate. Based on the separation in
time and sky position, we infer that these high-energy triggers are
unrelated.

One sky map is available at this time and can be retrieved from the
GraceDB event page: skymap.fits.gz, an initial localization generated by
BAYESTAR. The probability is concentrated in two main equatorial regions
around right ascensions of 1h and 13h. About 30% of the probability is
confined to the top 500 deg2.

Updates on our analysis of this event will be sent as they become
available.


GRB_name: GRB151022A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18444
SUBJECT: GRB 151022A: Enhanced Swift-XRT position
DATE:    15/10/22 23:32:37 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 2395 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151022A, 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 = 349.19671, +55.81182 which is equivalent
to:

RA (J2000): 23h 16m 47.21s
Dec (J2000): +55d 48' 42.6"

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: GRB151022A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18447
SUBJECT: GRB 151022A: MITSuME Okayama upper limits
DATE:    15/10/23 00:53:18 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 151022A (D'Avanzo et al., GCNC 18436)
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 2015-10-22 14:08:12 UT (~100 sec after the burst).
We did not find any new point source within the enhanced XRT circle
(Beardmore et al., GCNC 18444) 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
-----------------------------------------------------
0.00471    14:13:19     540.0   >19.0  >19.0  >18.3
0.04291    15:08:20    6240.0   >20.1  >19.9  >19.1
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151022A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18448a
SUBJECT: GRB 151022A: Swift-XRT refined Analysis
DATE:    15/10/23 02:22:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU)
and P. D'Avanzo report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 151022A (D'Avanzo et al.
GCN Circ. 18436), from 286 s to 31.4 ks after the  BAT trigger. The
data comprise 17 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
Beardmore et al. (GCN Circ. 18438).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.82 (+0.17, -0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.39 (+0.26, -0.24). The
best-fitting absorption column is  6.2 (+2.6, -1.5) x 10^21 cm^-2,
consistent with the Galactic value of 4.7 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 6.1 x 10^-11 (7.7 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.2 (+2.6, -1.5) x 10^21 cm^-2
Galactic foreground: 4.7 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.39 (+0.26, -0.24)

If the light curve continues to decay with a power-law decay index of
1.82, the count rate at T+24 hours will be 7.2 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x
10^-15 (5.5 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/00661036.

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

[GCN OPS NOTE(15Jun16):  Because of a processing error, two circulars
received the same ID Number.  The second was given an "a' suffix.]


GRB_name: GRB151022A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18449
SUBJECT: GRB 151022A: RATIR Upper Limits
DATE:    15/10/23 05:37:43 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 151022A (D'Avanzo, et al., GCN 18436) 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 2015/10 23.16 to 2015/10 23.18 UTC (13.77 to 14.17 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r, i, and z bands.  For a source within the Swift-XRT error circle (Beardmore, et al., GCN 18444), in comparison with the SDSS DR9, we obtain the following upper limits (3-sigma):

   r > 23.11
   i > 23.04
   z > 19.84

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: GRB151023A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18450
SUBJECT: GRB 151023A: Swift detection of a burst
DATE:    15/10/23 14:06:29 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
C. Pagani (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. G. R. Roegiers (PSU),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU) and
R. L. C. Starling (U Leicester) report on behalf of the Swift Team:

At 13:43:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151023A (trigger=661253).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 271.019, -8.323, which is 
   RA(J2000)  =  18h 04m 05s
   Dec(J2000) = -08d 19' 21"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 15 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 13:44:19.5 UT, 74.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 270.9847, -8.3165 which
is equivalent to:
   RA(J2000)  = 18h 03m 56.33s
   Dec(J2000) = -08d 18' 59.4"
with an uncertainty of 3.3 arcseconds (radius, 90% containment). This
location is 124 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper.  We cannot determine whether the source is
fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 4.10
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 796 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 1.42. 

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


GRB_name: GRB151022A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18452
SUBJECT: GRB 151022A: Swift-BAT refined analysis
DATE:    15/10/23 17:34:15 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC),S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
P. D'Avanzo (INAF-OAB), N. Gehrels (GSFC),H. A. Krimm (GSFC/USRA),
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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151022A (trigger #661036)
(D'Avanzo, et al., GCN Circ. 18436).  The BAT ground-calculated position is
RA, Dec = 349.223, 55.812 deg which is
  RA(J2000)  =  23h 16m 53.5s
  Dec(J2000) = +55d 48' 43.4"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.

The mask-weighted light curve shows a single FRED-like peak, with some
superimposed structure, peaking near the trigger time and fading to near
background by ~200 seconds. T90 (15-350 keV) is 116.7 +/- 23.0 sec
(estimated error including systematics).

The time-averaged spectrum from T-1.5 to T+132.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.98 +- 0.29.  The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+10.37 sec in the 15-150 keV band
is 0.8 +- 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/661036/BA/


GRB_name: GRB151022A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18456
SUBJECT: GRB 151022A: Swift/UVOT Upper Limits
DATE:    15/10/23 20:11:49 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

B. G. Balzer (PSU) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151022A
304 s after the BAT trigger (D'Avanzo et al., GCN Circ. 18436).
No optical afterglow consistent with the XRT position
(Evans GCN Circ. 18438) 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           304          454          147         >21.2
white              304         7836          902         >22.0
v                  461         8247          646         >20.1
b                  560         7632          430         >21.0
u                  535         7426          430         >21.2
w1                 510        12075          553         >19.7
m2                 486         8452          646         >20.3
w2                 609         8042          627         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.56 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151023A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18459
SUBJECT: GRB 151023A: Enhanced Swift-XRT position
DATE:    15/10/23 23:09:05 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 1446 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151023A, 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 = 270.98458, -8.31640 which is equivalent
to:

RA (J2000): 18h 03m 56.30s
Dec (J2000): -08d 18' 59.0"

with an uncertainty of 2.3 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: GRB151023A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18461
SUBJECT: GRB 151023A
DATE:    15/10/24 01:12:00 GMT
FROM:    Fabian Knust at MPE/GROND  <fknust@mpe.mpg.de>

F. Knust (MPE Garching), S. Klose (TLS Tautenburg), and J. Greiner 
(MPE Garching) report on behalf of the GROND team: 

We observed the field of GRB 151023A (Swift trigger 661253; D'Avanzo
et al., GCN #18450) 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 23:52 UT on Oct. 23rd 2015, 10 hrs after the
GRB trigger, and are continuing. They were performed at an average
seeing of 1.6" and at an average airmass of 1.6  
We found a single point source within the 2.3" Swift-XRT error circle
reported by Evans et al. (GCN #18459) at 

RA (J2000) = 18:03:56.244 
Dec. (J2000) = -08:18:57.42

with an uncertainty of 0.2" in each coordinate. 
Based on the first 4.4 min of total exposures in g'r'i'z' and 4.0 min
in JHK, we estimate preliminary magnitudes (all in AB system) of 

g'> 22.1 mag,
r' = 20.2 +/- 0.1 mag,
i' = 19.1 +/- 0.1 mag,
z' =18.4 +/- 0.1 mag,
J = 17.6 +/- 0.2 mag,
H = 17.0 +/- 0.1 mag, and
K = 17.3 +/- 0.2 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)=1.38
mag in the direction of the burst (Schlegel et al. 1998).                    

[GCN OPS NOTE(24oct15):  The suffix "A" was added to the Subject-line.]


GRB_name: GRB151023A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18462
SUBJECT: GRB 151023A: Swift/UVOT Upper Limits
DATE:    15/10/24 02:15:35 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU), B. G. Balzer (PSU) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151023A
796 s after the BAT trigger (D'Avanzo et al., GCN Circ. 18450).
No optical afterglow consistent with the XRT position
(D'Avanzo et al. GCN Circ. 18450) 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           796          946          147         >19.6
white              796         2140          411         >20.0
v                 1130         2191          136         >18.5
b                 1229         2116          117         >19.3
w1                1354         1374           19         >18.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.42 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151023A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18463
SUBJECT: GRB 151023A: Swift-XRT refined Analysis
DATE:    15/10/24 03:06:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri
(INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), T.G.R. Roegiers
(PSU), L.M. McCauley (PSU), C. Pagani (U. Leicester) and P. D'Avanzo
report on behalf of the Swift-XRT team:

We have analysed 7.4 ks of XRT data for GRB 151023A (D'Avanzo et al.
GCN Circ. 18450), from 756 s to 35.7 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. 18459).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.32 (+0.27, -0.21).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.7 (+1.1, -0.8). The
best-fitting absorption column is  2.7 (+1.8, -1.4) x 10^22 cm^-2, in
excess of the Galactic value of 4.1 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.9 x 10^-11 (2.6 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.7 (+1.8, -1.4) x 10^22 cm^-2
Galactic foreground: 4.1 x 10^21 cm^-2
Excess significance: 2.7 sigma
Photon index:      2.7 (+1.1, -0.8)

If the light curve continues to decay with a power-law decay index of
1.32, the count rate at T+24 hours will be 2.5 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-14 (6.4 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/00661253.

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


GRB_name: GRB151023A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18464
SUBJECT: GRB 151023A: RATIR Observations
DATE:    15/10/24 03:59:24 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 151023A (D'Avanzo, et al., GCN 18450) 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 2015/10 24.09 to 2015/10 24.14 UTC (12.35 to 13.66 hours after the BAT trigger), obtaining a total of 1.07 hours exposure in the r, i, and z bands.

We detect the GROND source (Knust, et al., GCN 18461) at a similar brightness level.  In comparison with the USNO-B1 catalog, we find:

   r 20.27 +/- 0.04
   i 19.10 +/- 0.02
   z 18.29 +/- 0.09

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 is present in the DSS at a comparable brightness level and may not, therefore, be the GRB afterglow.

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


GRB_name: GRB151022A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18465
SUBJECT: GRB 151022A: OSN optical upper limit
DATE:    15/10/24 11:29:51 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC), S. Jeong (IAA-CSIC/SKKU), V. Casanova, J. C. Tello (IAA-CSIC) and
A. J. Castro-Tirado (IAA-CSIC/UMA), report on behalf of a larger collaboration:

We observed the field of GRB 151022A (D'Avanzo et al., GCN Circ. 18436) with the 1.5m
OSN telescope at Observatorio de Sierra Nevada (Spain). The observations
were carried out in the I band on Oct 22.79163 - 22.84025 (4.89 - 6.06 hours
post bust). We do not detect any new optical source within the enhanced XRT 
error circle (Beardmore et al., GCN Circ. 18444) down to a limiting magnitude of I ~21.5 mag.


GRB_name: GRB151023A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18469
SUBJECT: GRB 151023A: Swift-BAT refined analysis
DATE:    15/10/24 19:18:03 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  J. R. Cummings (GSFC/UMBC),
P. D'Avanzo (INAF-OAB), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151023A (trigger #661253)
(D'Avanzo, et al., GCN Circ. 18450).  The BAT ground-calculated position is
RA, Dec = 271.012, -8.289 deg which is
  RA(J2000)  =  18h 04m 02.9s
  Dec(J2000) = -08d 17' 19.7"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 83%.

The mask-weighted light curve shows a single-pulse structure that starts at ~ T-1 s,
peaks at ~T0, and ends at ~ T+10 s. T90 (15-350 keV) is 10.66 +- 4.41 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.65 to T+12.16 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.24 +- 0.24.  The fluence in the 15-150 keV band is 2.6 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.03 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/661253/BA/


GRB_name: GRB151021A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18472
SUBJECT: GRB 151021A: Skynet PROMPT-CTIO/DSO17 observations of the optical afterglow
DATE:    15/10/26 12:27:55 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter@physics.unc.edu>

A. Trotter, D. Reichart, J. Haislip, A. Smith, D. Caton, L. Hawkins, J. Moore, N. Frank, M. Maples, E. Johnson, R. Joyner, J. Martin, C. Salemi, J. A. Crain, K. Ivarsen, A. LaCluyze, and M. Nysewander report:

Skynet observed the Swift BAT/XRT localization of GRB 151021A (Melandri et al., GCN 18425, Swift trigger=660671) with with one 16" telescope (PROMPT 5; I band) of the PROMPT array at CTIO, Chile, and with the 17" telescope at the Appalachian State University Dark Sky Observatory (DSO17; B band) in NC, USA. Starting at 2015-10-21 01:31:14 UT and continuing until 03:00 UT (t=2m-91m post-trigger), Skynet took a total of 38 exposures ranging from 10-160s. 

In the PROMPT I-band images, we clearly detect a fading optical afterglow at the position reported by de Ugarte Postigo et al. (GCN 18426), with I~14 at t=2m at I~19 at t=75m. A DSO17 B-band image taken at t=2.2m shows no source to a 3-sigma limit of B>15.7. 

A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb151021a.png

Limiting magnitudes are in the Vega System, calibrated to 4 APASS DR9 stars in the field.  Magnitudes have not been corrected for the small line-of-sight Milky Way dust extinction, with expected E(B-V)=0.009 (Schlafly & Finkbeiner 2011).

No further Skynet observations are scheduled.


GRB_name: GRB151006A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18475
SUBJECT: GRB 151006A: CALET Gamma-Ray Burst Monitor detection
DATE:    15/10/27 00:49:24 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence) 
and the CALET collaboration:

The long-duration GRB 151006A (Kocevski et al., GCN Circ. 18398; Cummings  et al., 
GCN Circ. 18409; Roberts & Meegan, GCN Circ. 18404; Golenetskii et al., GCN Circ. 18413; 
Bhalerao et al., GCN Circ. 18422) triggered the CALET Gamma-Ray Burst Monitor (CGBM) 
at 09:54:59.97 UT on 6 October 2015.   The clear burst signal was detected by the Soft 
Gamma-ray Monitor (SGM; 30 keV - 20 MeV) which is a scintillation detector utilized a BGO 
crystal.  Due to a large incident angle of the event, no signal was detected by the Hard X-ray 
Monitor (HXM; 7 keV - 1 MeV) which is a scintillation detector composed of a LaBr3(Ce) crystal.  

The SGM light curve shows two spikes peaking at T0-2s and T0+2s, and the emission ending 
around T0+~60s.  The T90 duration measured by the SGM data is 63 +- 5 s (30 - 1000 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm


GRB_name: GRB151027A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18478
SUBJECT: GRB 151027A: Swift detection of a burst with a bright optical afterglow
DATE:    15/10/27 04:16:31 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Maselli (INAF-IASFPA), A. D'Ai (INAF-IASFPA),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU),
M. Stamatikos (OSU/NASA/GSFC) and T. N. Ukwatta (LANL) report on
behalf of the Swift Team:

At 03:58:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151027A (trigger=661775).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 272.491, +61.381 which is 
   RA(J2000) = 18h 09m 58s
   Dec(J2000) = +61d 22' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
peaked structure lasting at least 150 seconds.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~110 sec after the trigger. 

The XRT began observing the field at 03:59:51.1 UT, 87.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 272.4886, 61.3515 which is equivalent to:
   RA(J2000)  = +18h 09m 57.26s
   Dec(J2000) = +61d 21' 05.4"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 106 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 95 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 18:09:56.68 = 272.48615
DEC(J2000) = +61:21:13.4 = 61.35373
with a 90%-confidence error radius of about 0.61 arc sec. This position is 9.06
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.46 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. Maselli (maselli AT ifc.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18479
SUBJECT: GRB 151027A: KAIT optical afterglow confirmation
DATE:    15/10/27 04:22:02 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 151027A (Maselli et al.,
GCN 18478) immediately after receiving the trigger. 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.
Inside the XRT error circle we detected an un-cataloged varying
source with coordinates of :

RA =  18:09:56.70 (J2000)
DEC= +61:21:13.01 (J2000)

The object location is consistent with the position reported
from UVOT (Maselli et al., GCN 18478). The object has clear band mag
of ~13.0 at the moment.

Follow-up observations are encouraged.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18480
SUBJECT: GRB 151027A : ISON-NM early optical detection 
DATE:    15/10/27 05:47:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

L. Elenin (KIAM),  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 Swift GRB 151027A (Maselli et al., GCN 18478) 
with 0.4-m telescope of ISON-NM observatory in robotic mode starting on 
Oct., 27 (UT) 03:59:43  i.e. 79 seconds after burst trigger. We obtained 50 
unfiltered images of 30 s exposure. We clearly detect the optical 
counterpart of GRB 151027A  (Maselli et al., GCN 18478; Zheng and 
Filippenko, GCN 18479) in coordinates (J2000) 18 09 56.69 +61 21 13.2. In 
the first image we estimated brightness of the optical counterpart as ~14m.


GRB_name: GRB151027A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18481
SUBJECT: GRB 151027A: P60 afterglow confirmation and rebrightening
DATE:    15/10/27 05:57:03 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

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

The Palomar 60-inch robotic telescope responded automatically to the 
alert for GRB 151027A (Maselli et al., GCN151027A) and began a sequence 
of i, r, and z-band imaging at 04:00:49 UT, 145 seconds after the BAT 
trigger.   We identify a very bright afterglow consistent with the UVOT 
and KAIT (Zheng et al., GCN18479) positions in all filters.

The preliminary afterglow light curve shows a slow rise to a peak at 
about ~5 minutes after the GRB trigger, then slowly fades by about 1 
magnitude between then and approximately 30 minutes after the trigger. 
Over the next 20 minutes it then rapidly rebrightens by about 0.7 
magnitude.  Little or no fading is seen after that point (through to at 
least 90 minutes after the trigger.)

Continued monitoring is encouraged, and should remain possible even from 
small telescopes for quite some time.  High-resolution spectroscopy is 
also strongly encouraged.


GRB_name: GRB151027A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18482
SUBJECT: GRB 151027A: Enhanced Swift-XRT position
DATE:    15/10/27 09:37:18 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 1445 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 151027A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 272.48695, +61.35344 which is equivalent
to:

RA (J2000): 18h 09m 56.87s
Dec (J2000): +61d 21' 12.4"

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: GRB151027A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18483
SUBJECT: Tentative redshift for GRB 151027A from Swift-XRT data
DATE:    15/10/27 10:03:40 GMT
FROM:    Sergio Campana at INAF-OAB  <sergio.campana@brera.inaf.it>

S. Campana (INAF-OAB) report on behalf of the Swift Team:

Swift BAT triggered on the early activity of GRB 151027A (Maselli et
al. 2015, GCN 18478). Swift XRT started observing 87 s after the
trigger observing the main event. By using the Swift/XRT spectrum
repository at http://www.swift.ac.uk/xrt_spectra/ (see Evans et al.
2009, MNRAS, 397, 1177) we selected a time interval with an almost
constant hardness ratio, starting at 150 s after the burst onset
and lasting 281 s. We then fit the Window Timing (WT) spectrum with
XSPEC using the model tbabs*ztbabs*pow.
We assume a Galactic column density of 3.75x10^20 cm^-2 (Willingale et
al. 2013, MNRAS, 431, 394) and we allow for a 30% uncertainty in the fit.
We fit the spectrum using C-statistics (C-stat=593.74 with 637 d.o.f.).
In the intrinsic column density vs. redshift plane there is just one 
deep minimum
hinting for a redshift z=0.38+/-0.17 (90% confidence level) and an
intrinsic column density N_H(z)=(3.6+/-0.7)x10^21 cm^-2.
The X-ray spectrum is soft with Gamma=2.6, (assuming a cut-off power
law spectrum the allowed redshift range expands to 0.27-1.38).

The contour plot is available at
http://www.brera.inaf.it/utenti/campana/151027.gif


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18485
SUBJECT: GRB 151027A: Weihai optical observations
DATE:    15/10/27 12:17:48 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

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

We observed the field of GRB 151027A (Maselli et al., GCN 18478) using 
the 1m telescope located at Weihai, Shandong, China. Observations 
started at 09:44 UT on 2015-07-27, i.e., 5.77 hr after the burst. We 
obtained 5x300s R-band and 5x150s I-band frames.

The afterglow (e.g., Maselli et al., GCN 18478; Zheng & Filippenko, GCN 
18479; Elenin et al., GCN 18480; Perley & Cenko, GCN 18481) is clearly 
detected in each image, and it has decayed to m(R) = 16.0 +/- 0.1 mag 
for the first R-band exposure, calibrated with the nearby USNO B1 stars 
(with R2 magnitudes).


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18487
SUBJECT: GRB 151027A: Keck/HIRES redshift
DATE:    15/10/27 13:57:31 GMT
FROM:    Daniel Perley at Caltech  <dperley@astro.caltech.edu>

D. A. Perley (DARK/NBI), L. Hillenbrand (Caltech), and J. X. Prochaska 
(UCO/Lick) report:

We obtained a 900s spectrum of the optical afterglow of GRB 151027A 
(Maselli et al., GCN 18478) with Keck/HIRES starting at UT 06:54 on 
2015-10-27.  In the preliminary reduction, we identify a series of 
strong absorption lines including the MgII doublet at z=0.81. Associated 
MgI, FeII, and (likely) FeII* are also present, indicating that this is 
the redshift of the GRB.  Analysis is ongoing.


GRB_name: GRB151027A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18490
SUBJECT: GRB 151027A: Swift-XRT refined Analysis
DATE:    15/10/27 16:16:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A.
D'ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A.
Kennea (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester)
and A. Maselli report on behalf of the Swift-XRT team:

We have analysed 6.0 ks of XRT data for GRB 151027A (Maselli et al. GCN
Circ. 18478), from 80 s to 18.9 ks after the  BAT trigger. The data
comprise 1.6 ks in Windowed Timing (WT) mode (the first 5 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. 18482).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=4.1 (+1.1, -1.0). At T+208 s  the decay
flattens to an alpha of 1.46 (+0.10, -0.14). The light curve breaks
again at T+537 s to a decay with alpha=0.04 (+0.06, -0.09),  and  again
at T+2494 s s to alpha=1.11 (+0.15, -0.26),  before a final break at
T+11.6 ks s after which the decay index is 2.01 (+0.26, -0.25).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.851 (+0.024, -0.023). The
best-fitting absorption column is  1.96 (+0.18, -0.17) x 10^21 cm^-2,
at a redshift of 0.81, in addition to the Galactic value of 3.8 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 1.99 (+/-0.08) and a best-fitting absorption column of 3.3 (+/-0.6)
x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.5 x 10^-11 (4.7 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.8 x 10^20 cm^-2
Intrinsic column:    3.3 (+/-0.6) x 10^21 cm^-2 at z=0.81
Photon index:      1.99 (+/-0.08)

If the light curve continues to decay with a power-law decay index of
2.01, the count rate at T+24 hours will be 0.035 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x
10^-12 (1.7 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/00661775.

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


GRB_name: GRB151027A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18491
SUBJECT: GRB 151027A: MITSuME Akeno Optical observation 
DATE:    15/10/27 16:23:13 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

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

We observed the field of GRB 151027A (A. Maselli et al., GCN Circular #18478) 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 2015-10-27 09:13:52 UT ( 5.25 h after the burst).
We detected the previously reported optical afterglow of GRB 151027A 
(WeiKang Zheng et al., GCN Circular #18479) in the g',Rc and Ic band.

The measured magnitudes are listed below.

T0+[sec] MID-UT  T-EXP[sec]       g'                   Rc                 Ic
------------------------------------------------------------------------------------------------------------------
 18928     09:34:24      2220     16.72+/-0.06 15.62+/-0.05 16.00+/-0.04
------------------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151027A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18492
SUBJECT: GRB 151027A: Fermi GBM observation
DATE:    15/10/27 16:31:56 GMT
FROM:    Hoi-Fung Yu at MPE  <sptfung@mpe.mpg.de>

Kilian Toelge, Hoi-Fung Yu (both MPE), and Charles A. Meegan (USRA)
report on behalf of the Fermi GBM Team:

"At 03:58:24.03 UT on 27 Oct 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151027A (trigger 467611108 / 151027166),
which was also detected by the Swift (Maselli et al. 2015, GCN 18478)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 10 degrees.

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

The GBM light curve consists of three pulses
with a duration (T90) of about 124 s (50-300 keV).
The time-averaged spectrum from T0-2.048 s to T0+133.120 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.41 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 340 +/- 63 keV.

The event fluence (10-1000 keV) in this time interval is
(1.94 +/- 0.09)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+0.3840 s in the 10-1000 keV band
is 11.37 +/- 0.34 ph/s/cm^2.

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


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18493
SUBJECT: GRB 151027A: GMG observation
DATE:    15/10/27 16:43:32 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Zhang, J. Mao and J. Bai (YNAO) report:


We observed the field of GRB 151027A (Maselli et al., GCN 18478) with the 2.4-meter optical telescope at Gao-Mei-Gu of Yunnan Observatories. Observations began at 11:34:08 UT, Oct 27, 2015, about 7.5 hr after the trigger. We obtained a low S/N spectrum. The feature of absorption line identified as MgII by Perley et al. (GCN 18487) is clearly shown, and redshift is 0.81. However, we noticed that some possible absorption lines might be identified as OVI and NaID, indicating a redshift of 0.33. We cannot have confirmation due to the low S/N of the spectrum. We also performed multi-band photometry and we obtained R~16.9 mag.
Further analysis is ongoing.


       
  


GRB_name: GRB151027A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18495
SUBJECT: GRB 151027A: Early RAPTOR Observations
DATE:    15/10/27 18:16:09 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 follow-up observations
of Swift trigger 661775 (Maselli et al., GCN 18478).  Our narrow-field
instruments in Los Alamos, NM USA, began imaging at 03:58:48.01 UT (23.86 s
after the BAT trigger time).  From the first frame we detected a bright optical
counterpart at the location reported by UVOT.  Starting with a magnitude of R~13.7
the RAPTOR telescopes measured a complex, fading lightcurve with seveal
re-brightening intervals.


GRB_name: GRB151027A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18496
SUBJECT: GRB 151027A: Swift-BAT refined analysis
DATE:    15/10/27 18:51:53 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), A. Maselli (INAF-IASFPA), T. Sakamoto (AGU),
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 151027A (trigger #661775)
(Maselli et al., GCN Circ. 18478).  The BAT ground-calculated position is
RA, Dec = 272.498, 61.361 deg which is
  RA(J2000)  =  18h 09m 59.6s
  Dec(J2000) = +61d 21' 39.6"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 18%.

The mask-weighted light curve shows a complex structure with roughly two main
pulses. The first pulse starts at ~T0, peaks at ~T+1 s, and ends at ~T+5 s. The
second pulse starts at ~T+90 s, peaks at ~T+110 s, and ends at ~T+170 s.
T90 (15-350 keV) is 129.69 +- 5.55 sec (estimated error including systematics).

The time-averaged spectrum from T-0.74 to T+164.70 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.72 +- 0.05.  The fluence in the 15-150 keV band is 7.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.20 sec in the 15-150 keV band
is 6.8 +- 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/661775/BA/


GRB_name: GRB151027B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18499
SUBJECT: GRB 151027B: Swift detection of its 1000-th burst
DATE:    15/10/27 22:56:57 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. D'Ai (INAF-IASFPA),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
A. Maselli (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
R. L. C. Starling (U Leicester) report on behalf of the Swift Team:

At 22:40:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151027B (trigger=661869).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 76.238, -6.427, which is 
   RA(J2000)  =  05h 04m 57s
   Dec(J2000) = -06d 25' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a peak 
with a duration of about 50 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~40 sec after the trigger. 

The XRT began observing the field at 22:44:04.0 UT, 203.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 76.21944, -6.45010 which
is equivalent to:
   RA(J2000)  = 05h 04m 52.67s
   Dec(J2000) = -06d 27' 00.4"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 106 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 9.43
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 5.37e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 209 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
0.25. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18501
SUBJECT: GRB 151027B: NOT optical afterglow candidate
DATE:    15/10/28 00:19:30 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), Nial R. Tanvir (Univ. Leicester), Dong Xu 
(NAOC/CAS), Jussi Harmanen (NOT and Univ. Turku), Thomas Reynolds (NOT 
and Turku Univ.), and Pere Blay Serrano (IAC/NOT), report on behalf of a 
larger collaboration:

We observed the field of the #1000 Swift GRB 151027B (Ukwatta et al., 
GCN 18499) with the Nordic Optical Telescope equipped with the StanCam 
imager. Observations started on 2015 Oct 27.988 UT (1.04 hr after the 
GRB trigger), as soon as the field was observable from La Palma.

In our first 5-minute image taken in the R band, we detect a single 
source consistent with the XRT position (Ukwatta et al., GCN 18499), at 
coordinates (J2000):

RA = 05:04:52.69
Dec = -06:27:00.8

with an uncertainty of 0.5".

Calibrating the image against nearby USNO stars, we measure for this 
object R = 18.44 +- 0.05 (Vega). While we have not yet any variability 
information, the positional consistency with the XRT error circle and 
the lack of any object in the DSS at this location suggest that this is 
the optical afterglow of GRB 151027B.


GRB_name: GRB151027A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18502
SUBJECT: GRB 151027A: UVOT Observations
DATE:    15/10/28 01:04:14 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

B. G. Balzer (PSU), M. H. Siegel (PSU) and A. Maselli (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151027A
96 s after the BAT trigger (Maselli et al., GCN Circ. 18478). We confirm
the source initially reported by Maselli et al. (GCN Circ. 18478) and
since observed by numerous ground-based observatories (Zheng and Filippenko,
GCN Circ. 18479; Elenin et al., GCN Circ. 18480; Perley and Cenko, GCN Circ.
18481; Xu et al., GCN Circ. 18485; Yano et al., GCN Circ. 18491; Wren et al.,
GCN Circ. 18495).  We report a position of:

  RA(J2000)  = +18h 09m 57.26s
  Dec(J2000) = +61d 21' 05.4"

The light curve shows complex behavior, with marginal evidence of brightening
after the initial finding chart, then fading with a decay slope of 0.6-0.8 over
the first orbit. The second orbit magnitudes are consistent with no fading
from those measured at the end of the first orbit while the third orbit
shows significant fading.

Preliminary detections 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)       95        245        147     14.52+-0.02
white           589        609         19     14.44+-0.04
white           762        782         19     14.71+-0.04
white           858       1008        147     14.81+-0.02
white          1161       1354         38     15.07+-0.04
white          1510       1529         19     15.23+-0.04
white          6449       6649        197     15.28+-0.01
white         23966      24662        677     17.14+-0.01
v               639       1579        116     15.12+-0.04
b               564       1505         97     15.37+-0.03
u               308       1479        323     14.00+-0.03
w1              688       1455         77     14.71+-0.05
m2              663       1598         88     14.98+-0.06
w2              615       1555        116     15.12+-0.05

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: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18503
SUBJECT: GRB 151027A: THO optical observations
DATE:    15/10/28 02:54:58 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 151027A optical afterglow at Taurus Hill Observatory
(A95) using Meade 16" ACF 0.40-m/8.0  telescope and SBIG ST-8XME CCD.
The observations were started at 2015-10-27 17:11:39 (UT). Eight photometric
R filter and eight photometric V filter images with 300 sec exposure time were
taken.

The afterglow was detected at the following position RA 18:09:56.72 and
DEC +61:21:13.2.

The following magnitudes were obtained from the observations using
NOMAD1 1512-0243178 (R=13.200 and V=13.670) as a comparison star:

Tmid(h)+T0    Filter      Exp. time         Mag          Mag. Err.
13.393              R          4x300s              17.06      0.12
13.747              V          4x300s              17.56      0.25
14.103              R          4x300s              17.06      0.09
14.457              V          4x300s              17.49      0.10


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GRB_name: GRB151027B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18504
SUBJECT: GRB 151027B: Enhanced Swift-XRT position
DATE:    15/10/28 03:56:46 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 1168 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 151027B, 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 = 76.21941, -6.45016 which is equivalent
to:

RA (J2000): 05h 04m 52.66s
Dec (J2000): -06d 27' 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: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18505
SUBJECT: GRB 151027B: VLT/X-shooter redshift
DATE:    15/10/28 06:34:50 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

D. Xu (NAOC/CAS), N. R. Tanvir (U. Leicester), D. Malesani, J. Fynbo (DARK) report:

We observed the optical afterglow of GRB 151027B (Ukwatta et al. GCN 18499, Malesani et al. GCN 18501) with the VLT X-shooter spectrograph covering a spectral range 3400A to 18000A. Observations began at 2015 Oct 28 03:50 UT, approximately 5h09m post-burst.

The spectrum shows a clear continuum in the red, with a strong break corresponding to Ly-alpha at a redshift of z=4.063.  This is supported by detection of absorption lines of Si II 1259/1260, Si II* 1265, CII 1335, CII* 1336, OI 1302, SiII 1304, S IV 1394/1403, CIV 1548/1551, FeII 1608 and Al II 1671 at that redshift. We therefore propose this as the redshift of the 1000th Swift GRB.

We thank the staff at Paranal, particularly T. Rivinius, for their support in obtaining these observations.


GRB_name: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18506
SUBJECT: GRB 151027B: VLT/X-shooter redshift
DATE:    15/10/28 06:35:40 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC/CAS), N. R. Tanvir (U. Leicester), D. Malesani, J. P. U. 
Fynbo (DARK) report on behalf of a larger collaboration:

We observed the optical afterglow of GRB 151027B (Ukwatta et al. GCN 
18499, Malesani et al. GCN 18501) with the VLT X-shooter spectrograph 
covering a spectral range 3400A to 18000A. Observations began at 2015 
Oct 28 03:50 UT, approximately 5h09m post-burst.

The spectrum shows a clear continuum in the red, with a strong break 
corresponding to Ly-alpha at a redshift of z=4.063.  This is supported 
by detection of absorption lines corresponding to Si II 1259/1260, Si 
II* 1265, CII 1335, CII* 1336, OI 1302, SiII 1304, S IV 1394/1403, CIV 
1548/1551 and Al II 1671 at that redshift. We therefore propose this as 
the redshift of the GRB.

We thank the staff at Paranal, particularly T. Rivinius and I. Condor, 
for their support in obtaining these observations.


GRB_name: GRB151027B
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18507
SUBJECT: GRB 151027B: GROND Optical/NIR Afterglow Detection
DATE:    15/10/28 07:40:47 GMT
FROM:    Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>

P. Wiseman, J. Greiner (both MPE Garching) report on behalf of the GROND
team:

We observed the field of GRB 151027B (Swift trigger 661869; (Ukwatta et
al., GCN 18499) 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 06:24 UT on 28/10/2015, 7 hrs 45 mins after the
GRB trigger, and are continuing. They were performed at an average seeing
of 0.9" and at an average airmass of 1.1.

We found a single point source within the enhanced 1.8" Swift-XRT error
circle reported by Evans et al. (GCN 18504), common with that reported by
Malesani et al. (GCN 18501) and Xu et al. (GCN 18505).

Based on 6.6 min of total exposures in g'r'i'z'JHK at a mid time of
06:33:39 UT, we estimate preliminary magnitudes (all in AB system) of

g' > 22.4 mag,
r' = 20.8 +/- 0.08 mag,
i' = 20.1 +/- 0.07 mag,
z' = 20.1 +/- 0.07 mag,
J = 20.1 +/- 0.4 mag,
H = 19.1 +/- 0.3 mag, and
K > 18.3 mag.

A clear g'-band drop out in the SED leads to a photo-z of 4.3 + 0.3,-0.2,
consistent with the redshift derived from the X-shooter spectrum (Xu et
al., GCN 18505). The source appears to be fading relative to the NOT
report (Malesani et al., GCN 18501), and has continued to do so during our
observations.

Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as
well as 2MASS field stars (JHK) and are not corrected for the expected
Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.2
mag in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB151027A
Detection_method: VLA Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18508
SUBJECT: GRB 151027A: VLA detection
DATE:    15/10/28 08:47:38 GMT
FROM:    Tanmoy Laskar at UC Berkeley  <tanmoylaskar@gmail.com>

T. Laskar (NRAO / UC Berkeley), K. Alexander, and E. Berger (Harvard)
report on behalf of a larger collaboration:

"We observed GRB 151027A (Maselli et al.; GCN 18478) at multiple
frequencies with the VLA beginning on 2015 October 27.95 UT (0.78 days
after the burst). At a mean frequency of 21.8 GHz, we detect a bright radio
source with a preliminary flux density of ~ 1.7 mJy at

RA = 18:09:56.691 +/- 0.001
Dec = 61:21:13.03 +/- 0.02

consistent with the enhanced Swift/XRT position (Goad et al.; GCN 18482)
and the optical position (Maselli et al.; GCN 18478, Zheng et al.; GCN
18479, Hentunen et al.; GCN 18503). Follow-up observations are planned. We
thank the VLA staff for rapidly scheduling these observations."


GRB_name: GRB151027B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18509
SUBJECT: GRB 151027B: Swift-XRT refined Analysis
DATE:    15/10/28 10:57:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), A. D'ai (INAF-IASFPA), A. Maselli  (INAF-IASFPA),
L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team:

We have analysed 12 ks of XRT data for GRB 151027B (Ukwatta et al. GCN
Circ. 18499), from 191 s to 32.5 ks after the  BAT trigger. The data
comprise 61 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. 18504).

The light curve can be modelled with an initial power-law decay with an
index of alpha=5.7 (+/-0.6), followed by a break at T+332 s to an alpha
of 0.66 (+0.05, -0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.81 (+0.14, -0.13). The
best-fitting absorption column is  4.1 (+2.5, -2.2) x 10^22 cm^-2, at a
redshift of 4.063, in addition to the Galactic value of 9.4 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 3.8 x
10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 9.4 x 10^20 cm^-2
Intrinsic column:    4.1 (+2.5, -2.2) x 10^22 cm^-2 at z=4.063
Photon index:      1.81 (+0.14, -0.13)

If the light curve continues to decay with a power-law decay index of
0.66, the count rate at T+24 hours will be 0.026 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.9 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/00661869.

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


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18510
SUBJECT: GRB 151027A: LCOGT-McDonald afterglow observations
DATE:    15/10/28 12:16:09 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

S. Dichiara (U. Ferrara, ICRANet), D. Kopac (U. Ljubljana), C. Guidorzi 
(U. Ferrara), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of 
a larger collaboration report:

The 1-m LCOGT McDonald observatory began observing Swift GRB 151027A 
(Maselli et al. GCN 18478) on October 28, 01:29:27 UT (0.90 days after 
the burst trigger) with SDSS R and I filters. We clearly detect the 
optical afterglow (Maselli et al.; Zheng & Filippenko GCN 18479; Elenin 
et al. GCN 18480; Perley & Cenko GCN 18481; Xu et al. GCN 18485) with 
the following magnitudes:

Mid Time      Exposure       Filter       Magnitude
(days)           (s)
-------------------------------------------------------
0.90            5x120         R           16.87 +- 0.04
0.91            6x120         I           17.26 +- 0.05
-------------------------------------------------------

Calibration is done against nearby USNOB-1 star RA(J2000)=18:09:53.742, 
DEC(J2000)=+61:20:57.27, assuming R2=17.21 mag and I=17.17 mag. We note 
the presence of another USNOB-1 object at RA(J2000)=18:09:56.489, 
DEC(J2000)=+61:21:10.64, lying at 3.1 arcsec from the GRB afterglow.


GRB_name: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18511
SUBJECT: GRB 151027B: MASTER-NET early OT detection 
DATE:    15/10/28 13:24:39 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

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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

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
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)


Two MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO and IAC was pointed to the  GRB151027B (Ukwatta et. al GCN 
18499) 25 sec after notice time and 156 sec after trigger time at 
2015-10-27 22:43:19 UT. On our first (30s exposure)  set we haven't found 
optical transient (Malesani et. al. GCN 18501, Xu et. al. GCN 18505, 
Wiseman et. al GCN 18507)  within SWIFT error-box. The 2-sigma upper limit 
has been about 17.7 mag. The observations were significantly complicate 
the closest distance to the Moon (~ 35 d). The Moon background light is 
picked up the sky background on our cameras more than 10 times. Therefore, 
we could not get deep enough image. Nevertheless, we detect OT on a 
several coadd images in consequent time  in  SAAO.
The first time we see  OT 475 seconds after the trigger with magnitude ~ 
18.9.  OT had a slight brightening 1736 seconds after the trigger to 18.5 
mag.
The preliminary photometry available at table below.

Table 1. GRB151027B MASTER-SAAO Early photometry.

T-Ts    T-Tm     Exptime   Mag.(P/+P\)   Coadd
159      174     2 x 30     >17.7          1
201      221     2 x 40     >18.0          1
252      277     2 x 50     >18.3          1
313      343     2 x 60     >18.3          1
384      424     2 x 80     >18.4          1
159      311     2 x 260    >19.0          5
475      842     2 x 690     18.9          5
1235    1736     2 x 900     18.5          5
2264    3280    2 x 1800     18.9         10
3499    4515    2 x 1800     19.1         10

T - is trigger time, Ts - exposure start time, Tm - exposure middle time.


We see OT in separate polarizations on s/n~5 confidence lewel. Table 1 
shows the averaged data from two mutually perpendicular polarization.


The message may be cited.


GRB_name: GRB151027B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18512
SUBJECT: GRB 151027B: RATIR Observations
DATE:    15/10/28 14:10:19 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J.  Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 151027B (Ukwatta et al., GCN 18499) 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 2015/10 28.26 to 2015/10 28.51 UTC (7.46 to 13.55 hours after the BAT trigger), obtaining a total of 3.51 hours exposure in the r, i, and z bands.

We detect a source at 05:04:52.69 -06:27:00.8 (J2000, +/-0.05), within the Swift-XRT error circle. In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections:

   r =  20.83 +/- 0.05
   i =  20.18 +/- 0.04
   z =  19.49 +/- 0.21

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

This source coincides with the source reported by Malesani et al. (GCN 18501), Xu et al. (GCN 18505), Wiseman et al. (GCN 18507), and Buckley et al. (GCN 18511). The source appears to have faded since these earlier observations and furthermore fades by about 0.5 mag in i over the course of our observations.

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


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18513
SUBJECT: GRB 151027A: continued GMG observation
DATE:    15/10/28 14:16:34 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Zhang, J. Mao and J. Bai (YNAO) report:


We observed the field of GRB 151027A (Maselli et al., GCN 18478) with the 2.4-meter optical telescope at Gao-Mei-Gu of Yunnan
Observatories. Observations began at 11:32:30 UT, Oct. 28, 2015, about 31.5 hr after the trigger. We clearly detected the 
afterglow of GRB 151027A. The magnitude was estimated as R=18.9 +/- 0.1 mag. 


GRB_name: GRB151027B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18514
SUBJECT: GRB 151027B: Swift-BAT refined analysis
DATE:    15/10/28 14:29:31 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),  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 151027B (trigger #661869)
(Ukwatta, et al., GCN Circ. 18499).  The BAT ground-calculated position is
RA, Dec = 76.188, -6.428 deg which is
  RA(J2000)  =  05h 04m 45.0s
  Dec(J2000) = -06d 25' 40.2"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 17%.

The mask-weighted light curve shows a complex structure with several
overlapping peaks that starts at  ~T0 and ends at ~T+100 s. T90 (15-350 keV)
is 80.00 +- 35.78 sec (estimated error including systematics).

The time-averaged spectrum from T+1.00 to T+97.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.83 +- 0.27.  The fluence in the 15-150 keV band is 1.5 +- 0.3 x 10^-6 erg/cm2.
The 1-s peak photon flux is unconstrained due to the weakness of the burst.
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/661869/BA/


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18515
SUBJECT: GRB 151027A :  Xinglong TNT optical observation
DATE:    15/10/28 14:37:57 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  observed  GRB 151027A (Maselli et al., GCN 18478)  
with Xinglong  0.8-m TNT telescope at 2015-10-27 and 2015-10-28.
 
The optical afterglow (Maselli et al., GCN 18478;  Zheng & Filippenko 
GCN 18479; Elenin et al., GCN 18480;  Perley & Cenko GCN 18481; Xu et al, 18485; 
Zhang et al., GCN 18513) was clearly detected in our multi-band images.
The brightness of the optical afterglow is decayed for about 2.5 mag in R-band 
during our observations as shown in follows:
==============================
Date             Time(UT)       filter  mag   merr            
2015-10-27  11:21:59          R       16.2    0.1
2015-10-28  11:04:00          R       18.7    0.1
==============================
Calibrated by the USNO B1.0 R2 mag

More observations are encouraged. 

The message may be cited.


GRB_name: GRB151027A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18516
SUBJECT: Konus-Wind observation of GRB 151027A
DATE:    15/10/28 14:43:29 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, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team, report:

The long-duration GRB 151027A
(Swift-BAT trigger #661775: Maselli et al., GCN Circ. 18478,
Palmer et al., GCN Circ. 18496;
Fermi GBM detection: Toelge et al., GCN Circ. 18492)
triggered Konus-Wind at T0=14304.154 s UT (03:58:24.154).

The burst light curve consists of at least three pulses
with a total duration of ~120 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB151027_T14304/

As observed by Konus-Wind, the burst
had a fluence of 1.42(-0.21,+0.37)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.432 s,
of 2.22(-0.61,+0.62)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+131.328 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.44(-0.21,+0.24)
and Ep = 173(-46,+135) keV (chi2 = 78/77 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 77/76 dof)

The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.96(-0.28,+0.32)
and Ep = 91(-11,+14) keV (chi2 = 56/61 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 56/60 dof)

Assuming the redshift z=0.81 (Perley et al., GCN Circ. 18487)
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 ~2.4x10^52 erg,
the peak luminosity L_iso is ~7x10^51 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~310 keV.

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


GRB_name: GRB151027B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18517
SUBJECT: GRB 151027B: Swift/UVOT Upper Limits
DATE:    15/10/28 15:45:21 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and T. N. Ukwatta (LANL) report on behalf of 
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151027B 
210 s after the BAT trigger (Ukwatta et al., GCN Circ. 18499).
No optical afterglow consistent with the XRT position (Osborne et al. 
GCN Circ. 18504) 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           210          359          147         >20.0
white              210         4545          344         >20.5
v                  366         4956          216         >18.8
b                 4141         5737          354         >20.6
u                 3935         5571          393         >20.4
w1                 415         5366          397         >20.4
m2                4961         5161          197         >19.1
w2                4551         4751          197         >19.9

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.25 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB151027A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18518
SUBJECT: GRB 151027A: T100 observations
DATE:    15/10/28 17:37:17 GMT
FROM:    Eda Sonbas at NASA/GSFC  <edasonbas@gmail.com>

E. Sonbas (Adiyaman Univ.), T. Guver (Istanbul Univ.), E. Gogus (Sabanci
Univ.), O. Erece, M. Kocak, S. Eryilmaz, H. Kirbiyik (TUG) report on behalf
of a larger collaboration


We observed the field of Swift GRB 151027A (Maselli et al., GCN#18478) with
the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory,
Turkey), starting October, 27, 18:32:21 UT (~ 14.5 hours after the
trigger). Observations were carried out in the R filter. The afterglow is
detected in the R band images with an exposure time of 150 s.


Using USNO-B1 star USNO-B1 1513-0237223 (R.A.=272.49, Dec=+61.37) in the
field, the magnitudes of the OT were estimated as follows;


t-t0 (hr) exp.(s) filt mag err (+/-)

14.56 150 R 16.8 0.06

14.61 150 R 17.2 0.08


Analysis of further observations with the same filter is ongoing.


We thank to TUBITAK National Observatory for a partial support in using
T100 telescope with project number 10CT100-95 and technical support.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18519
SUBJECT: GRB 151027A: NOT optical and NIR observations
DATE:    15/10/28 18:13:41 GMT
FROM:    Zach Cano at U of Iceland  <zewcano@gmail.com>

Z. Cano (U. Iceland), D. Malesani (DARK/NBI), Jussi Harmanen (NOT & U.
Turku), Thomas Reynolds (NOT & U. Turku.),  Pere Blay Serrano (IAC/NOT) and
P. Jakobsson (U. Iceland) report on behalf of a larger collaboration:

We observed the field of Swift GRB 151027A (Maselli et al., GCN Circ.
18478) with the Nordic Optical Telescope equipped with the StanCam
(optical) and NOTCam (NIR) imagers, in filters BVRI and JHK, respectively.
Observations started at 20:53 UT on 27 October 2015.  The OT (Maselli et
al.) is detected all filters.

A summary of our observations follows:

Filter       t-t0 (hr)      Mag +- Merr
-----------------------------------------
B            17.94          21.4 +- 0.2
R            18.17          20.6 +- 0.1
I            18.28          19.2 +- 0.1
J            16.92          18.2 +- 0.1
H            17.38          18.3 +- 0.1
K            17.60          17.2 +- 0.2

The optical filters are calibrated to USNO-B1 and the NIR filters to 2MASS,
where a single star that appeared in both catalogs was used for the
zeropoint calculation.  These magnitudes are not corrected for foreground
extinction.

When these extinguished magnitudes are converted to monochromatic fluxes
(using the zeropoints from Fukugita et al. 1995; Hewett et al. 2006), a
single power-law with an exponent of -1.25 provides an acceptable fit to
the optical-to-NIR spectral energy distribution.

â€‹


GRB_name: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18520
SUBJECT: GRB 151027B: LCOGT FTN afterglow observations
DATE:    15/10/28 20:13:07 GMT
FROM:    Simone Dichiara at Ferrara U/Italy  <dichiara@fe.infn.it>

S. Dichiara (U. Ferrara, ICRANet), D. Kopac (U. Ljubljana), C. Guidorzi
(U. Ferrara), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of
a larger collaboration report:

The 2-m Faulkes Telescope North in Hawaii began observing Swift
GRB 151027B (Ukwatta et al., GCN 18499) on October 28, 12:18:25 UT, i.e.,
~ 13.6 hours after the burst trigger, with the r' and i' filters.

Although we did not detect the optical counterpart (Malesani et al.,
 GCN 18501; Xu et al., GCN 18505; Wiseman et al., GCN 18507;
Buckley et al., GCN 18511; Watson et al., GCN 18512) in the r'
filter (R > 20.3), the source is detected in the i' filter with
I = 19.6 +/- 0.3 mag at a mid time of 13.9 hours post burst
(total exposure in i' of 600 s).

The magnitude is calibrated against nearby USNO-B1 stars.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18521
SUBJECT: GRB 151027A: SAO RAS optical observations
DATE:    15/10/28 23:18:01 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. Moskvitin (SAO RAS, Russia), report on behalf of the larger GRB
follow-up team:

The field of the GRB 151027A (Maselli et al., GCNC #18478) was observed
with the Zeiss-1000, 1 meter telescope of SAO RAS on the October, 28.
The observations started 36.3 hours after the trigger.
Two series of 300 sec. images in Rc band: 6 frames (16:13:57--16:56:20 UT)
and 3 frames (17:32:15--17:50:33 UT) were obtained under the tolerable
weather conditions.

The OT is clearly detected in the stacked frames:
#  T_mid-T0,h   exp,s      R_mag
1  36.612       6 x 300    18.7 +/- 0.1
2  37.717       3 x 300    18.9 +/- 0.1

The photometry is based on nearby USNO-B1 stars proposed
by A. Pozanenko (IKI RAS). The observations were provided with the help
of the SAO RAS staff: V. Komarov, O. Spiridonova and R. Uklein.


GRB_name: GRB151029A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18522
SUBJECT: GRB 151029A: Swift detection of a burst with an optical counterpart
DATE:    15/10/29 08:49:18 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

T. N. Ukwatta (LANL), A. D'Ai (INAF-IASFPA), J. A. Kennea (PSU),
A. Maselli (INAF-IASFPA), P. T. O'Brien (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 07:49:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151029A (trigger=662086).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 38.529, -35.354, which is
   RA(J2000)  =  02h 34m 07s
   Dec(J2000) = -35d 21' 14.4"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Lightcurve data is not immediately available. 

Using promptly downlinked data we find an uncatalogued X-ray source
with an enhanced position: RA, Dec 38.5280, -35.3855 which is
equivalent to:
   RA(J2000)  = 02h 34m 06.72s
   Dec(J2000) = -35d 23' 07.7"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
position is 113.4 arcsec from the BAT position. 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 3.41
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 209 seconds after the BAT trigger. The initial
2.7'x2.7' sub-image does not cover the XRT error circle. There is a candidate
afterglow in the UVOT srclist at:
RA(J2000) =   02:34:08.08 = 38.527964
DEC(J2000) = +35:23:08.8 = -35.385784
with a 90%-confidence error radius of about 0.61 arc sec. This position is 1.06
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.34 with a 1-sigma error of about 0.04. No correction has been made for the
expected extinction. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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: GRB151029A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18523
SUBJECT: GRB 151029A: GROND afterglow observations
DATE:    15/10/29 09:15:29 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>

F. Knust, J. Bolmer, T. Kruehler (all MPE Garching), S. Schmidl
(TLS Tautenburg) and J. Greiner (MPE Garching) report:

We observed the field of GRB 151029A (Swift trigger 662086,
Ukwatta et al., GCN 18522)  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 October 29, 2015, 08:33, about
40 minutes after the GRB trigger. Inside the X-ray error
(Ukwatta et al., GCN 18522) circle we detect the UVOT
counterparts at coordinates

RA: 02:34:06.75
Decl: -35:23:08.6

with an error of around 0".5.

At a mean time of October 29, 2015, 08:37 UTC, we measure
the following preliminary AB magnitudes and upper limits of:


g' = 19.9 +- 0.1
r' = 19.7 +- 0.1
i' = 19.7 +- 0.1
z' = 19.7 +- 0.1
J = 19.5 +- 0.2
H > 19.4
K > 19.4

Magnitudes and upper limts are calibrated against GROND zeropoints
and 2MASS field stars and are not corrected for the Galactic
extinction corresponding to a reddening of E_B-V = 0.018 mag
(Schlafly & Finkbeiner 2011) in the direction of the burst.


GRB_name: GRB151029A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18524
SUBJECT: GRB 151029A VLT/X-shooter redshift
DATE:    15/10/29 10:48:11 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

Nial R. Tanvir (Univ. Leicester), Thomas Kruehler (MPE), Daniele
Malesani (DARK/NBI), Dong Xu (NAOC/CAS), Antonio de Ugarte Postigo
(IAA-CSIC),  Giovanna Pugliese (API/UvA) report on behalf of
a larger collaboration:

We observed the optical counterpart of GRB 151029A (Ukwatta et al., GCN
18522; Knust et al., GCN 18523) using the ESO Very Large Telescope UT2
equipped with the X-shooter spectrograph. Observations started on Oct
29.369 UT (1.02 hr after the GRB), that is at the end of the Chilean
night, and were extended over twilight.

The optical counterpart (Ukwatta et al., GCN 18522; Knust et al., GCN
18523) is clearly detected in our grz acquisition images.

We detect a faint continuum throughout the spectral range of
our observations, from about 3300A to 18000A, indicating
an upper limit to the redshift of z~2.  We also detect several
weak absorption features that would be consistent with being
MgII (2796/2804) and FeII (2344/2587/2600) lines at z=1.423,
which we therefore report as the likely redshift for this GRB.

We acknowledge expert support from the ESO observing staff, in
particular Thomas Rivinius and Marcela Espinoza.


GRB_name: GRB151027A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18525
SUBJECT: GRB 151027A: MAXI/GSC detection
DATE:    15/10/29 11:01:12 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

T. Masumitsu, H. Negoro, (Nihon U.), N. Kawai (Tokyo Tech), T. Sakamoto (AGU),
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, 
T. Takagi, M. Matsuoka (RIKEN), T. Yoshii, Y. Tachibana (Tokyo Tech), 
A. Yoshida, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, R. Imatani (Osaka U.), 
M. Nakajima, 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:

MAXI/GSC performed scanning observations at the region of 
GRB 151027A (Maselli et al. GCN 18478) for 48 sec each 
at the centroid time 03:38:56, 1168 s before the Swift trigger, and 
05:11:32, 4388 s after the Swift trigger.
No positive 4-10 keV flux was obtained at the former scan transit
with the 3 sigma upper limit of 0.037 photons/cm2/s (~ 31 mCrab).
At the latter scan transit, the 4-10 keV flux was 0.0166 +/- 0.0175 
photons/cm2/s (~ 14 +/- 15 mCrab). 
The detection is not significant, but the flux is consistent with 
the interpolation from the Swift/XRT light curve (V. D'Elica et al. #18509).


GRB_name: GRB151029A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18526
SUBJECT: GRB 151029A: Enhanced Swift-XRT position
DATE:    15/10/29 12:08:13 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 789 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151029A, 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 = 38.52779, -35.38553 which is equivalent
to:

RA (J2000): 02h 34m 6.67s
Dec (J2000): -35d 23' 07.9"

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

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

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


GRB_name: GRB151029A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18527
SUBJECT: GRB 151029A: Swift-BAT refined analysis
DATE:    15/10/29 12:22:22 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151029A (trigger #662086)
(Ukwatta, et al., GCN Circ. 18522).  The BAT ground-calculated position is
RA, Dec = 38.537, -35.356 deg, which is 
   RA(J2000)  =  02h 34m 09.0s 
   Dec(J2000) = -35d 21' 21.7" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 41%.
 
The mask-weighted light curve shows two overlapping peaks starting 
at ~T-2 sec, peaking at ~T+1 se, and ending at ~T+10 sec.
T90 (15-350 keV) is 8.95 +- 2.32 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.10 to T+10.47 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.49 +- 1.08, 
and Epeak of 33.9 +- 6.9 keV (chi squared 53.8 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 3.9 +- 0.6 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T-0.15 sec in the 15-150 keV band is
1.8 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.16 +- 0.19 (chi squared 64.3 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/662086/BA/


GRB_name: GRB151027B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18529
SUBJECT: GRB 151027B: Swift UVOT detection
DATE:    15/10/29 15:34:43 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and T. N. Ukwatta (LANL) report on behalf of
the Swift/UVOT team:

In Swift/UVOT followup observations of GRB 151027B (Ukwatta et al., GCN 
Circ. 18499) a source is found in the summed up V filter exposures at a 
position consistent with the XRT (Osborne et al., GCN Circ. 18504) and 
the optical/NIR counterparts reported by Malesani et al. GCN Circ. 
18501, Xu et al. GCN Circ. 18505, Wiseman and Greiner GCN Circ. 18507, 
Buckley et al. GCN Circ. 18511, Watson et al. GCN Circ. 18512, and 
Dichiara et al. GCN Circ. 18520.

A preliminary detection using the UVOT photometric system (Breeveld et 
al. 2011, AIP Conf. Proc. 1358, 373) for V data taken in the first and 
second segment is:

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

v                     191       28529     1986   20.8 Â± 0.3

The magnitudes in the table are not corrected for the strong Galactic
extinction due to the reddening of E(B-V) = 0.25 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB151029A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18530
SUBJECT: GRB 151029A: LCOGT-FTS afterglow observations
DATE:    15/10/29 15:42:47 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

S. Dichiara (U. Ferrara, ICRANet), C. Guidorzi (U. Ferrara), S. 
Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of a larger 
collaboration report:

The 2-m LCOGT Faulkes Telescope South began observing Swift GRB 151029A 
(Ukwatta et al. GCN 18522) on October 29, 09:33 UT (1.7 hours after the 
burst trigger) with SDSS R and I filters. We marginally detect the 
optical afterglow (Ukwatta et al. GCN 18522; Knust et al. GCN 18523; 
Tanvir et al. GCN 18524) due to poor sky conditions with the following 
magnitudes:

Mid Time      Exposure       Filter       Magnitude
(hours)           (s)
-------------------------------------------------------
1.8            5x120         R           20.6 +- 0.4
2.0            5x120         I           21.0 +- 0.5
-------------------------------------------------------

Calibration is done against nearby USNOB-1 star RA(J2000)=02:34:10.069, 
DEC(J2000)=-35:24:13.54, assuming R2=16.95 mag and I=17.63 mag.


GRB_name: GRB151029A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18531
SUBJECT: GRB 151029A: Swift/UVOT Detection
DATE:    15/10/29 19:51:56 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151029A
92 s after the BAT trigger (Ukwatta et al., GCN Circ. 18522).
A source consistent with the XRT position (Beardmore et al., GCN Circ. 18526)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  02:34:06.72 =  38.52799 (deg.)
  Dec (J2000) = -35:23:08.6  = -35.38573 (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               92          242          147         16.98 +/- 0.03
v                  634          653           19         17.66 +/- 0.32
b                  560          752           39         19.24 +/- 0.33
u                  304          554          246         17.35 +/- 0.06
w1                 683          703           19        >17.98
m2                 658          850           39        >18.17
w2                 609          802           39        >18.64

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: GRB151029A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18532
SUBJECT: GRB 151029A: Swift-XRT refined Analysis
DATE:    15/10/29 20:49:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'ai (INAF-IASFPA), A. Maselli  (INAF-IASFPA), J.A. Kennea (PSU), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), A.
Melandri (INAF-OAB) and T.N. Ukwatta report on behalf of the Swift-XRT
team:

We have analysed 15 ks of XRT data for GRB 151029A (Ukwatta et al. GCN
Circ. 18522), from 106 s to 35.4 ks after the  BAT trigger. The data
comprise 23 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Beardmore et al. (GCN Circ. 18526).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.08 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.30 (+0.31, -0.29). The
best-fitting absorption column is  3.0 (+3.7, -3.0) x 10^21 cm^-2, at a
redshift of 1.423, in addition to the Galactic value of 3.4 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 (3.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.4 x 10^20 cm^-2
Intrinsic column:    3.0 (+3.7, -3.0) x 10^21 cm^-2 at z=1.423
Photon index:      2.30 (+0.31, -0.29)

If the light curve continues to decay with a power-law decay index of
1.08, the count rate at T+24 hours will be 8.0 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x
10^-14 (2.9 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/00662086.

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


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18533
SUBJECT: GRB 151027A: Optical counterpart detection
DATE:    15/10/29 21:34:24 GMT
FROM:    Valentyna Golovnya at Main Astro Obs,Kyiv  <golov_v@ukr.net>

    Yu. Protsyuk (RI NAO), O. Kovalchuk (RI NAO) report: 

  
  
    
        
    
  
  
    We observed the field of the Swift GRB 151027A (Maselli et al. 
  
  
    GCN 18478) with 0.5-m telescope Mobitel KT-50 of Nikolaev observatory 
  
  
    with Alta-U9000 CCD-camera with R filter in robotic mode 
  
  
    from Oct., 28 (UTC) 20:34:16 till 20:59:59. 
  
  
    We obtained 19 unfiltered images of 60 s exposure and calculated 
  
  
    coordinates and magnitudes of all detected objects in UCAC4 system. 
  
  
    We don't detect any optical counterpart of GRB 151027A (Maselli et al. 
  
  
    GCN 18478; Zheng and Filippenko, GCN 18479) in coordinates near (J2000) 
  
  
    18 09 56 +61 21 12 up to ~17.2- 17.5 m . 
  
  
    After that we filtered all images and detected optical 
  
  
    counterpart in 6 images in coordinates (J2000) 
  
  
    18 09 56.680 (SD=0.s081) +61 21 12.08 (SD=0."63) 
  
  
    with brightness near 18.3m (SD=0.3m) 
    
      
    
  
 


GRB_name: GRB151029A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18534
SUBJECT: GRB 151029A: MITSuME Ishigakijima upper limits
DATE:    15/10/30 05:19:18 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

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

We observed the field of GRB 151029A (Ukwatta et al., GCNC 18522)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

The observation started on  2015-10-29 14:56:55 UT (~6.5h after
the burst). We could not detect the previously reported afterglow
(Ukwatta et al., GCNC 18522; Knust et al., GCNC 18523;
Tanvir et al., GCNC 18524) in all the three bands.

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

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc     Ic
-----------------------------------------------------
0.31392    15:56:55    5760.0   >20.5  >20.7  >19.8
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151029A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18535
SUBJECT: Correction to the Trigger Time for Swift GRB 151029A
DATE:    15/10/30 12:54:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. Barthelmy and F. Marshall (GSFC) on behalf of the Swift team:

In GCN Circular 18522, we stated that the trigger time for GRB 151029A 
was 07:49:54 UT, but with the full data set downlinked, the correct trigger time
is 07:49:39 UT.  The correction for the on-board clock drift had not
been applied in the original Circular due to the lack of some of the
real-time TDRSS downlinked data.  We apologise for any inconvenience.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18537
SUBJECT: GRB 151027A: Continued P60 Monitoring
DATE:    15/10/30 14:37:08 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

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

We have continued to image the optical afterglow of GRB151027A (Maselli et al., GCN 18478) with the robotic Palomar 60-inch telescope (see Perley et al., GCN 18481). We report the following r-band photometry, calibrated with respect to nearby point sources from the APASS survey:

t_mid                                time since burst (d)          Magnitude

2015-10-29T02:14:14      1.93                                   19.63 +/- 0.04
2015-10-30T02:02:28      2.92                                   20.48 +/- 0.08

This implies a relatively steep power-law decay index of ~ 1.9 at these times.

Continued observations are planned.


GRB_name: GRB151031A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18538
SUBJECT: GRB 151031A: Swift detection of a burst
DATE:    15/10/31 06:06:57 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Sonbas (Adiyaman Univ.), V. D'Elia (ASDC), L. Izzo (URoma/ICRA),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 05:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151031A (trigger=662330).  Swift slewed to the burst after
a 6 minute delay due to viewing constraints. 
The BAT on-board calculated location is 
RA, Dec 83.199, -39.092 which is 
   RA(J2000) = 05h 32m 48s
   Dec(J2000) = -39d 05' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 05:57:43.9 UT, 433.6 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 83.19532, -39.12049 which is equivalent
to:
   RA(J2000)  = 05h 32m 46.88s
   Dec(J2000) = -39d 07' 13.8"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 103 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 2.62
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 439 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 0.03. 

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


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18539
SUBJECT: GRB 151027A: optical follow-up observations
DATE:    15/10/31 06:39:13 GMT
FROM:    Patrick Wiggins at Wiggins Obs  <paw@digis.net>

P. Wiggins reports:

Observed GRB 151027A with a .35-meter optical telescope at my home observatory, IAU 718, on 2015 October 27 from 0433 to 0732 UTC using a clear filter and obtained the following:

GRB Countpart: 18h 09m 56.71s  +61d 21m 12.78s
Reference One: 18h 10m 05.68s  +61d 23m 14.97s
Reference Two: 18h 09m 51.53s  +61d 22m 48.87s

Julian Date       Date          Ref. C    Ref. K    Var. V    C-K       Differential 
Mid Exposure   yyyy-mm-dd.ddddd Raw Mag.  Raw Mag.  Raw Mag.  Differ.   Mag.        
-------------- ---------------- --------- --------- --------- --------- ------------
2457322.689715 2015 10 27.18972    -2.937    -3.111    -1.085     0.174       15.051
2457322.692866 2015 10 27.19287    -2.433    -2.622    -1.355     0.190       14.278
2457322.700101 2015 10 27.20010    -2.732    -2.925    -1.433     0.192       14.499
2457322.703174 2015 10 27.20317    -2.921    -3.112    -1.605     0.191       14.516
2457322.724392 2015 10 27.22439    -2.909    -3.088    -1.391     0.180       14.718
2457322.758285 2015 10 27.25829    -2.949    -3.142    -1.151     0.193       14.998
2457322.786495 2015 10 27.28649    -2.906    -3.085    -0.916     0.180       15.189
2457322.801286 2015 10 27.30129    -2.901    -3.108    -0.722     0.207       15.379
2457322.814370 2015 10 27.31437    -2.879    -3.079    -0.406     0.201       15.673
END


GRB_name: GRB151031A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18540
SUBJECT: GRB 151031A: VLT/X-shooter optical counterpart and redshift
DATE:    15/10/31 07:23:44 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), N. R. Tanvir (Univ. Leicester), T. Kruehler 
(MPE), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), H. Flores 
(GEPI/Paris obs), D. Xu (NAOC/CAS), J.P.U. Fynbo (DARK/NBI), report on 
behalf of the X-shooter GRB collaboration:

We observed the field of GRB 151031A (Sonbas et al., GCN 18538) with the 
ESO Very Large Telescope UT2 (Kueyen) equipped with the X-shooter 
spectrograph. Observations were carried out using the automatic "rapid 
response mode" (RRM), and started immediately following the reception of 
the XRT position notice.

In the acquisition images, we detect a single source consistent with the 
position of the XRT afterglow, at coordinates (J2000):

RA = 05:32:47.11
Dec = -39:07:19.1

We measure for this object R = 20.4 +- 0.1 (calibrated against three 
nearby USNO stars) in an image taken on Oct 31.2565 UT, that is 18.8 min 
after the GRB.

A sequence of spectra with increasing exposure time (3 to 32 min) was 
secured covering the wavelength range 3,000 - 25,000 AA. From the 
analysis of the first 8 min data, several absorption features can be 
seen on top of the object continuum, which we interpret as due to Ca II, 
Mg I, Mg II and Fe II in absorption at a common redshift of z = 1.167. 
In the visible arm, an emission feature is also seen, corresponding to 
[O ii] at a consistent redshift, which we thus consider to be the 
redshift of GRB 151031A. Analysis of the full data set is ongoing.

We acknowledge excellent support from the ESO observing staff in 
Paranal, in particular Thomas Rivinius, Marcela Espinoza, and Claudia Cid.


GRB_name: GRB151031A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18541
SUBJECT: GRB 151031A: Enhanced Swift-XRT position
DATE:    15/10/31 08:21:55 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 436 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 151031A, 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 = 83.19596, -39.12134 which is equivalent
to:

RA (J2000): 05h 32m 47.03s
Dec (J2000): -39d 07' 16.8"

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


GRB_name: GRB151031A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18542
SUBJECT: GRB 151031A: Swift-BAT refined analysis
DATE:    15/10/31 14:25:39 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

T. N. Ukwatta (LANL),S. D. Barthelmy (GSFC), 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),
E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU), (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 151031A (trigger #662330)
(Sonbas, et al., GCN Circ. 18538).  The BAT ground-calculated position is
RA, Dec = 83.189, -39.125 deg which is
    RA(J2000)  =  05h 32m 45.3s
    Dec(J2000) = -39d 07' 28.3"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.

The mask-weighted light curve shows a single FRED-shaped peak, peaking at T+2 sec
and returning to background by T+7 sec. T90 (15-350 keV) is 5.00 +- 2.24 sec
(estimated error including systematics).

The time-averaged spectrum from T+0.30 to T+6.30 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.41 +- 0.18.  The fluence in the 15-150 keV band is 3.2 +- 0.3 x 10^-7erg/cm2.
The 1-sec peak photon flux measured from T+1.30 sec in the 15-150 keV band
is 1.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/662330/BA/


GRB_name: GRB151027B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18543
SUBJECT: GRB 151027B: RATIR Late-Time Upper Limits
DATE:    15/10/31 15:12:21 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JosÃ© A. de Diego (UNAM), Leonid Georgiev (UNAM), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 151027B (Ukwatta, et al., GCN 18499) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir from 2015/10 31.23 to 2015/10 31.52 UTC (78.85 to 85.85 hours after the BAT trigger), obtaining a total of 5.20 hours exposure in the r, i, and z bands.

We no longer detect the optical afterglow (Malesani et al., GCN 18501).  In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

   r > 23.45
   i > 23.39
   z > 18.57

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 AstronÃ³mico Nacional in San Pedro MÃ¡rtir.


GRB_name: GRB151031A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18544
SUBJECT: GRB 151031A: Swift-XRT refined Analysis
DATE:    15/10/31 18:07:05 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), T.G.R. Roegiers (PSU), P.A. Evans (U. Leicester), S.L. Gibson
(U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB) and E. Sonbas report on behalf of the Swift-XRT
team:

We have analysed 7.5 ks of XRT data for GRB 151031A (Sonbas et al. GCN
Circ. 18538), from 443 s to 25.5 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. 18541).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.56 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.13 (+0.22, -0.21). The
best-fitting absorption column is  9.4 (+3.8, -3.3) x 10^21 cm^-2, at a
redshift of 1.167, in addition to the Galactic value of 2.6 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 3.2 x
10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 2.6 x 10^20 cm^-2
Intrinsic column:    9.4 (+3.8, -3.3) x 10^21 cm^-2 at z=1.167
Photon index:      2.13 (+0.22, -0.21)

If the light curve continues to decay with a power-law decay index of
0.56, the count rate at T+24 hours will be 0.010 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-13 (4.7 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/00662330.

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


GRB_name: GRB151030A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18545
SUBJECT: GRB 151030A: Fermi GBM observation
DATE:    15/10/31 20:35:30 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

Peter Veres (UAH) reports on behalf of the Fermi GBM Team:

"At 23:58:22.6 UT on 30 October 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151030A (trigger 467942306 / 151030999).

The on-ground calculated location, using the GBM trigger
data, is RA = 297.4, DEC = 31.1 (J2000 degrees,
equivalent to 19 h 49 m, 31 d 08 '), with an uncertainty
of 1 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 30 degrees.

The GBM light curve consists of two separate peaks
with a duration (T90) of about 117 s (50-300 keV).
The time-averaged spectrum from T0-5 s to T0+150 s is
adequately fit by a Band function with Epeak = 241 +/- 11 keV,
alpha = -1.05 +/- 0.02, and beta = -2.09 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(5.45 +/- 0.01)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+104 s in the 10-1000 keV band
is 19.2 +/- 0.7 ph/s/cm^2.

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


GRB_name: GRB151031A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18546
SUBJECT: GRB 151031A: Swift/UVOT Detection
DATE:    15/10/31 22:42:11 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151031A
439 s after the BAT trigger (Sonbas et al., GCN Circ. 18538). A source
at the VLT position (Malesani et al, GCN Circ. 18540) and consistent with
the XRT position (Evans et al. GCN Circ. 18541) is detected in the initial
UVOT exposures.

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              439         1020          314         20.63 +/- 0.16
v                  595         8257          627        >20.1
b                  695         7642          588        >20.2
u                  670         7437          430         20.34 +/- 0.28
w1                 645         8677          635        >20.0
m2                 620         8462          627        >20.0
w2                 746         8053          607        >21.0

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: GRB151031A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18547
SUBJECT: GRB 151031A
DATE:    15/11/01 00:29:14 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 151031A (Sonbas et al., GCNC 18538)
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 2015-10-31 15:54:27 UT (10.1 h after
the burst). We could not detect the previously reported afterglow
(Malesani et al., GCNC 18540; Kuin and Sonbas, GCNC 18546) in
all the three bands.

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

#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.49617    17:44:59    6000.0   >18.6  >18.9  >18.5
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151027B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18548
SUBJECT: GRB 151027B: ATCA radio detection
DATE:    15/11/01 07:01:04 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

J. Greiner (MPE), M. Wieringa (CSIRO), P. Wiseman (MPE) report for a  
larger consortium: 
 
We observed the field of GRB 151027B (Swift trigger 661869; Ukwatta et 
al., GCN 18499) simultaneously at 5.5 and 9 GHz with the Australia  
Telescope Compact Array (ATCA), beginning at October 30.54 UT for 3.3 hrs.  
 
At a mean frequency of 9 GHz (with 2 GHz bandwidth) we detect a source 
at ~67+/-10 microJy at the position of the optical afterglow (Malesani  
et al., GCN 18501; Wiseman et al., GCN 18507). At the redshift of z=4.063  
(Xu et al., GCN 18506) this is among the most luminous GRB radio afterglows. 
 
We are grateful to P. Edwards for scheduling this observation. 


GRB_name: GRB151031A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18550
SUBJECT: GRB 151031A: GROND observation
DATE:    15/11/01 22:44:14 GMT
FROM:    John Graham at MPE/Garching  <graham@mpe.mpg.de>

S. Schmidl (TLS Tautenburg), J. Graham, and J. Greiner (both MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 151031A (SWIFT trigger 662330; Sonbas et al, GCN 18538) 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 November 1, 2015, at 06:42 UT, 1.04 days after the GRB trigger (due to being clouded out the previous night). They were performed at an average seeing of 1.52" and at an average airmass of 1.02.

We detect the source reported by Malesani et al. (GCN 18540) and Kuin et al. (GCN 18546).

Based on total exposures of 33 minutes in g'r'i'z' and 72 minutes in JHK, we measure the following preliminary magnitudes and upper limits (AB magnitude system):

g' = 22.1 +/- 0.1 mag,
r' = 21.9 +/- 0.1 mag,
i' = 21.7 +/- 0.1 mag,
z' = 21.5 +/- 0.1 mag,
J  = 21.6 +/- 0.3 mag,
H  = 20.7 +/- 0.3 mag, and
K  > 19.8 mag.

Given magnitudes and upper limits 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: GRB151031A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18551
SUBJECT: GRB 151031A: MITSuME Akeno optical upper limits 
DATE:    15/11/02 10:02:14 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, Y. Yano, 
Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)

report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151031A (E. Sonbas et al., GCN Circular #18538) 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 2015-10-31 16:18:19 UT (10.5 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
----------------------------------------------------------
37669  17:00:37  4440  > 18.8  > 18.9  > 18.3
----------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18552
SUBJECT: GRB 151027A: Correction to GCN 18519
DATE:    15/11/02 19:12:53 GMT
FROM:    Zach Cano at U of Iceland  <zewcano@gmail.com>

â€‹Z. Cano (U. Iceland) reports on behalf of a larger collaboration:

Upon further investigation, it was discovered that the magnitudes given in
GCN Circ. 18519 are incorrect.  The presented photometry was not for the
optical and NIR afterglow of GRB 151027A, but rather the fainter object
that is 3.1 arcsec SW of the afterglow (Dichiara et al. GCN Circ. 18510).

A revised summary of the NOT observations follows:

Filter       t-t0 (hr)      Mag +- Merr
-----------------------------------------
B            17.94          18.2 +- 0.1
R            18.17          17.9 +- 0.1
I            18.28          17.4 +- 0.1
J            16.92          16.4 +- 0.1
H            17.38          15.5 +- 0.1
K            17.60          15.1 +- 0.1

The optical filters are calibrated to USNO-B1 and the NIR filters to 2MASS,
where a single star that appears in both catalogs was used for the
zeropoint calculation.  These magnitudes are not corrected for foreground
extinction.

When these extinguished magnitudes are converted to monochromatic fluxes
(using the zeropoints from Fukugita et al. 1995; Hewett et al. 2006), a
single power-law with an exponent of -0.8 provides a good fit to the
optical-to-NIR spectral energy distribution.

My apologies for the confusion.â€‹


GRB_name: GRB151029A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18554
SUBJECT: GRB 151029A: FRAM optical afterglow detection
DATE:    15/11/03 13:42:46 GMT
FROM:    Martin Jelinek at Astro.Inst.ASU-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek (Astronomical Institute ASU-AVCR Ondrejov),
Michael Prouza, Jan Ebr, Petr Janecek, Martin Masek
(Institute of Physics FZU-CAS Praha) and
Samantha Oates (IAA CSIC Granada + UCL MSSL)

"The 0.30m robotic telescope FRAM located in Malargue,
Argentina, observed the reported location of GRB 151029A
(Ukwatta GCNC 18522) starting 884s after the corrected
trigger time (Barthelmy GCNC 18535), 8.9s after receiving
the trigger.

The telescope obtained a 30 minute set of unfiltered
exposures. The optical afterglow (Oates GCNC 18531,
Knust GCNC 18523, Tanvir GCNC 18524) can be detected
on combined exposures.

In the first combined image, with the mean time of individual
exposures 08:07:27 UT (1068s post trigger), we measure
magnitude 17.7 +/- 0.2. The calibration was done with three
nearby USNO-B2.0 stars."


GRB_name: GRB151027A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18555
SUBJECT: GRB 151027A: the missing GeV component
DATE:    15/11/03 18:21:32 GMT
FROM:    Remo Rufinni at ICRA  <ruffini@icra.it>

R. Ruffini, Y. Aimuratov, U. Barres, R. Belvedere, C.L. Bianco, M. Enderli, M. Kovacevic, R. Moradi, M. Muccino, A. Penacchioni, G.B. Pisani, J.A. Rueda, Y. Wang report:

From its overlapping [1] with GRB 090618, the prototype of binary-driven hypernovae (BdHNe), we can assert that this GRB belongs to the class of long GRBs originating in a binary system composed of a carbon-oxygen core and a companion neutron star (Rueda & Ruffini, 2012; Fryer et al. 2014).

At the redshift of z=0.81 (Perley et al, GCN 18487) the isotropic energy is Eiso ~ 4x10^(52) erg and the rest-frame spectral peak energy is Ep,i ~ 615 keV (Toelge et al., GCN 18492). A SN should appear after 13-15 days in rest-frame, namely between November 19th and November 23rd.

The exceptional feature of GRB 151027A is that, even if it belongs to the BdHN class, there is no high energy emission associated as of today although it was in the Fermi-LAT field of view (Toelge et al., GCN 18492). If confirmed this can be of support to probe the angular distribution of the high energy emission. Additional data in all wavelengths are requested for this most peculiar source.

[1] http://www.icranet.org/documents/GRB151027A.pdf


GRB_name: GRB150910A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18556
SUBJECT: GRB 150910A: CrAO optical observations
DATE:    15/11/03 19:13:53 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 150910A (Pagani et al., GCN
18264) with ZTSh telescope of CrAO observatory on Sep. 11 and Sep. 12.
We took several images in R,B-filters of 120 s exposure under good
weather conditions on Sep. 11 and non-optimal weather conditions (mean
seeing of 4") on Sep. 12.

The photometry of the afterglow (Pagani et al., GCN 18264; Zheng &
Filippenko, GCN 18265) is following

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

2015-09-11 17:56:37   1.3762   R        10*120  21.69 0.12   22.9
2015-09-11 18:18:31   1.4022   B        20*120  22.48 0.15   23.5
2015-09-11 18:39:47   1.4244   R        10*120  21.82 0.10   23.2
2015-09-11 19:22:17   1.4436   B        16*120  22.09 0.10   23.5
2015-09-12 18:04:32   2.3801   R        10*120  n/d   n/a    22.3

The photometry is based on SDSS stars used in GCN 18281 (Mazaeva et al.)


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18558
SUBJECT: GRB 151027A: Mt. Terskol observatory optical observation
DATE:    15/11/04 10:08:22 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Kozlov (IC AMER, NASU),  M. Andreev (Terskol Branch of INASAN), E. 
Mazaeva (IKI), A. Sergeev (Terskol Branch of INASAN),  A. Volnova (IKI), A. 
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of GRB 151027A (Maselli  et al., GCN 18478) with 
Zeiss-600 telescope of Mt. Terskol observatory in R-filter starting on Oct. 
28 (UT) 21:23:11. We obtained several images in R-filter. The afterglow 
(Maselli et al., GCN 18478; Zheng and  Filippenko, GCN 18479) is clearly 
detected in a combined image. The photometry of the combined image is
following

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

2015-10-28 21:23:11 1.7431      R      25*120 19.56  0.12

The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
1513-0237223 16.66
1513-0237170 15.58
1513-0237251 16.81
1513-0237270 16.78


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18559
SUBJECT: GRB 151027A: Mondy optical observations
DATE:    15/11/04 17:58:29 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the Swift GRB 151027A  (Maselli  et al., GCN 18478) with 
AZT-33IK telescope of Sayan observatory (Mondy) on several epochs.   We 
obtained
images in R-filter  on Oct., 27-- Nov., 1 .  The afterglow (Maselli et al., 
GCN 18478; Zheng and  Filippenko, GCN 18479) is clearly detected in each 
epoch. Coordinates of the afterglow are (J2000) 18 09 56.66 +61 21 13.0 with 
uncertainties of 0.3 arcsec in each coordinate. We also detected the 
USNO-B1.0 source mentioned in GCN 18510 (Dichiara et al.) in a position 
(J2000) 18 09 56.44 +61 21 10.8 with uncertainties of 0.3 arcsec in each 
coordinate.

Preliminary photometry of the afterglow  on October-29 -- November, 1 is 
following

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


2015-10-29   13:18:41  2.4082   R         55*60   19.84  0.05
2015-10-30   12:11:18  3.3736   R         78*60   20.32  0.06
2015-10-31   12:47:18  4.3958   R         41*120 21.25  0.07
2015-11-01   12:28:18  5.3694   R        19*120  21.50  0.12

The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
1513-0237223 16.66
1513-0237170 15.58
1513-0237251 16.81
1513-0237270 16.78

Late time photometry could be influenced by the nearby USNO-B1.0 source.

The overall light curve of our observations as well as photometry reported 
in GCNs 18480, 18521,18558 can be found in
http://grb.rssi.ru/GRB151027A/GRB151027A_lc.png


GRB_name: GRB151107A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18564
SUBJECT: GRB 151107A: Swift detection of a possible burst
DATE:    15/11/07 17:39:22 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), S. B. Cenko (GSFC), N. Gehrels (NASA/GSFC) and
K. L. Page (U Leicester) report on behalf of the Swift Team:

At 17:19:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151107A (trigger=662757).  Swift could not
slew to the burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 217.139, -59.680 which is 
   RA(J2000) = 14h 28m 33s
   Dec(J2000) = -59d 40' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for an image trigger,
the immediately-available BAT lightcurve shows no obvious activity. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 15:26 UT on 2015 December 12. There will thus be no XRT
or UVOT data for this trigger before this time. 

We note that this location is within a degree of the Galactic plane,
so this may be a Galactic transient.  Further determination of the
nature of the source will require the full downlinked dataset. 

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: GRB151107A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18565
SUBJECT: GRB 151107A: MASTER-NET optical observations
DATE:    15/11/07 19:56:02 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

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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

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
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-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru), 
located in SAAO, received Swift  GRB 151107A at the sunset, when the Sun 
altitude was -3.4 degrees, GRB altitude was 18.4 degrees.

MASTER-SAAO was pointed to the  GRB151107A 1750 sec after notice time 
and 2141 sec after trigger time at 2015-11-07 17:55:20 UT (Sun Altitude: 
-10.34, Alert altitude: 14.75). On our images (180s exposure)  we haven't 
found optical transient  within SWIFT error-box (ra=14 28 33 dec=-59 40 46 
r=0.05). The 5-sigma upper limit has been about 17.2mag. There is  a 
bright star near the BAT coordinates. GRB is setting.

The best single image was started at   2015-11-07 18:49:45  (exp 180) 
m_lim = 18.3 mag.
The message may be cited.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18567
SUBJECT: GRB 151027A: Hankasalmi optical observations
DATE:    15/11/08 09:04:54 GMT
FROM:    Arto Oksanen at Nyrola Obs., Finland  <oksanen@nyrola.jklsirius.fi>

Arto Oksanen (Hankasalmi Obs., Hankasalmi, Finland) reports the 
following observations of GRB 151027A (Maselli et al. 2015, GCN Circular 
#18478; Zheng et al. 2015, GCN Circular #18479, and many subsequent 
Circulars) to the AAVSO High Energy Network:

A. Oksanen observed the location of GRB 151027A using the Hankasalmi 
Observatory 0.4-m Richey-Chretien telescope using an SBIG STL-1001E 
camera.  Time-series images were obtained with both Rc and clear 
filters, with fifty 60-second frames obtained in each filter.  Clear 
filtered images were obtained between 16:27:07 UT and 22:01:23 UT on 
2015 October 27, and Rc-filtered images were obtained between 18:59:58 
and 21:45.04 UT.  Photometry was performed using an ensemble of 
comparison stars with APASS photometry available from AAVSO VSP 
(www.aavso.org/vsp). The afterglow is detected in both Rc- and 
clear-filtered observations, with evidence of fading between the start 
and end of the observing run.

Photometry of co-added groups of images yields the following:

Clear filter:

t-t0(d)     m(CR)     err(CR)
0.5235      16.872    0.030
0.5334      16.816    0.030
0.6531      17.160    0.044
0.6644      17.322    0.047
0.7468      17.575    0.065


Rc filter:

t-t0(d)     m(R)     err(R)
0.6365      17.257    0.058
0.6848      17.544    0.074
0.7353      17.580    0.118

These magnitudes of GRB 151027A are consistent with other magnitudes 
obtained at similar epochs of this burst (e.g. Hentunen et al. GCN 
Circular #18503; Sonbas et al. #18518).


GRB_name: GRB151107A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18568
SUBJECT: GRB 151107A, Swift-BAT refined analysis
DATE:    15/11/08 17:04:20 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC),  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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151107A (trigger #662757)
( Lien et al., GCN Circ. 18564).  The BAT ground-calculated position is
RA, Dec = 217.139, -59.680 deg which is
  RA(J2000)  =  14h 28m 33.4s
  Dec(J2000) = -59d -40' -46.9"
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows no obvious structure. The event starts
before the beginning of captured data at T-239 sec and extends out past the
end of collected event data at T+910 sec when the source location left the FoV
when the spacecraft slewed to a new target.

This burst occurred during the period of recovering the thermal control system
(Barthelmy et al., GCN Circ. 18562). The CZT bias voltage has been reduced
to -150v (instead of the normal -200v) and as such the energy scale is not fully
calibrated. Therefore, an accurate spectral analysis is unavailable.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/662757/BA/


GRB_name: GRB151107B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18570
SUBJECT: GRB 151107B
DATE:    15/11/09 21:54:16 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

Matthew Stanbro (UAH) and Charles Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 20:24:52.30 UT on 07 November 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151107B (trigger 468620696 / 151107851).

The on-ground calculated location, using the GBM trigger
data, is RA = 31.3, DEC = 45.6, with an uncertainty
of 1.7 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 40 degrees.

The GBM light curve consists of 2 separate episodes
with a duration (T90) of about 139 s (50-300 keV).
The time-averaged spectrum from T0+2 s to T0+137 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.20 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 347 +/- 25 keV

The event fluence (10-1000 keV) in this time interval is
(3.11 +/- 0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.13 s in the 10-1000 keV band
is 10.9 +/- 0.2 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: GRB151107A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18571
SUBJECT: GRB 151107A: Further investigation of the source nature
DATE:    15/11/09 22:06:51 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), and D. M. Palmer (LANL) report on behalf of 
the Swift-BAT team:

We perform further investigation regarding the uncertainty of the source nature 
of GRB151107A (Lien et al., GCN Circ. 18564) due to its proximity to the 
Galactic plane (within 1 deg) and the featureless light curve.

Using analysis from the BAT transient monitor (Krimm et al., 2013), there is 
no significant emission in the 15-50 keV band at ~ 4000 s before and ~ 6000 s
after the event data (signal-to-noise ratio < 1.8 sigma). The source was out of 
the field of view for the immediate time outside the event data range due to
pre-planned telescope slews. A search in the daily mosaic images at the burst 
location shows a 4-sigma detection on Nov. 7 (12.5 mCrab) and 1.6 sigma on 
Nov. 8 (which corresponds to a 1-sigma upper limit of ~ 5 mCrab).

This flux level and time profile are consistent with a GRB, and appear dimmer 
and shorter than a usual accreting binary source during outburst. However, 
we cannot rule out other possible Galactic transients, such as thermonuclear 
bursts or flaring stars.

In addition, we note that within 20.3 arcsec of the revised BAT position is the 
bright M2/M3 type star designated HD 126577. It is possible that the BAT 
detections correspond to a flaring episode from HD 126577, although this 
star is not known for such episodes.


GRB_name: GRB151107B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18574
SUBJECT: GRB 151107B: Mini-MegaTORTORA limits on simultaneous optical emission
DATE:    15/11/10 17:29:27 GMT
FROM:    Sergey Karpov at SAO RAS  <karpov@sao.ru>

S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar,
E.Ivanov, E.Katkova, A.Perkov, N.Orekhova (OJS RPC PSI, Russia), A.Biryukov
(SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal
University, Russia)

The localization of Fermi GBM trigger 468620696 / GRB 151107B (Stanbro et al,
GCN Circ. 18570) has been observed by Mini-MegaTORTORA nine-channel wide-field
monitoring system (located at Special Astrophysical Observatory near Russian
6-m telescope and belonging to Kazan Federal University) before, during and
after the trigger time at 2015-11-07 20:24:52.30 UT. The whole final 1-sigma
localization box (as well as 6 more degrees around it) has been covered since
20:19:23 UT (T-329.3 s) and until 20:25:18 UT (T+25.7 s, thus covering the
brightest part of first gamma-ray peak) with temporal resolution of 0.1 s in
white light. Dedicated real-time transient detection pipeline did not detect
any events longer than 0.3 s and brighter than approximately V=10.5 mag. Visual
inspection of co-added images with 10 s effective exposure (summation of 100
consecutive frames each) has not revealed any variable source down to V=12.0
mag during that interval.

At 20:25:18 UT the system initiated a repointing following the initially
distributed GBM coordinates, and since 20:25:55 UT (T+62.7 s, during the
continuing gamma-ray activity) till 20:35:59 UT (T+666.7 s) acquired 20x9 deep
images with 30 s exposures in white light in a 30x30 degree field of view
centered on RA=24.1 Dec=44.8. The whole final 1-sigma localization was still
inside the field of view. Quick-look analysis of the acquired data has not
revealed any variable object down to roughly V=13.5 mag over that time interval.

The analysis is ongoing.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18575
SUBJECT: GRB 151027A: continued Mondy optical observations
DATE:    15/11/10 19:10:04 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We continue observations (GCN 18559) of the Swift GRB 151027A  (Maselli 
  et al., GCN 18478) with AZT-33IK telescope of Sayan observatory 
(Mondy).   We obtained images in R-filter  on Nov., 4, 5, 7-9. In a 
combined image obtained on Nov. 7 we clearly detect a galaxy which 
coincide with the object 1513-0237216 of USNO-B1.0 catalog.  The object 
was also mentioned in GCN 18510 (Dichiara et al.) and GCN 18559 (Mazaeva 
et al.)

The finding chart can be found in 
http://grb.rssi.ru/GRB151027A/GRB151027A_20151107_AZT33IK_host.png

The afterglow (Maselli et al., GCN 18478; Zheng and  Filippenko, GCN 
18479) is not well detected.  The afterglow might overlap with 
North-East wing of the galaxy. The galaxy could be suggested as a host 
galaxy of GRB 151027A.

Preliminary photometry of the galaxy is R= 20.60+/-0.04 at November, 7.

The photometry is based on nearby USNO-B1.0 stars referenced in GCN 18559.


GRB_name: GRB151107B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18576
SUBJECT: GRB 151107B: MASTER-NET OT detection  inside the FERMI error box
DATE:    15/11/10 21:15:27 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

E. Gorbovskoy, V. Lipunov, V.Shumkov, N.Tyurina, V.Kornilov, P.Balanutsa, 
A.Kuznetsov, D. Vlasenko
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.Senik
Kislovodsk Solar Station of the Pulkovo Observatory

O.Gress, K.Ivanov, N.M.Budnev, V.A.Poleshchuk
Irkutsk State University

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

V.Krushinski, I.Zalozhnih
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 IAC (Tenerife, Spain) was pointed to the FERMI GBM GRB151107B 
14 sec after notice time and 
60 sec after trigger time at 2015-11-07 20:25:52 UT. Our first (10s 
exposure)  set  limit is 16.8 within FERMI 
error-box (ra=00 42 28 dec=+48 48 58 r=4.5, Stanbro and Meegan, GCN 18570).

MASTER II  robotic telescope  located in Kislovodsk was pointed to the 
GRB151107B 21 sec after notice time and 66 sec after trigger time at 
2015-11-07 20:25:59 UT. Our first (10s exposure)  set limit is  18.1 
within FERMI error-box . The summary (60sec) unfiltered optical limit is 
19.5m.

MASTER II  robotic telescope located in SAAO (South Africa, Sutherland) 
was pointed to the  GRB151107B 20 sec after notice time and 66 sec after 
trigger time at 2015-11-07 20:25:58 UT. Our first (10s exposure)
set limit is 15.4.

There are prompt pointing observations because duration of the GRB is ~140 
s (Stanbro and Meegan, GCN 18570)

After 5 minutes of alert observations of the center of error box, 
telescopes in IAC and Kislovodsk started the inspect survey inside large 
Fermi error box (ra=00 42 28 dec=+48 48 58 r=4.533300)  obtained by GCN 
socket.

As a result, we cover more than 98% of 1 sigma+systematic  and 85% of 
3-sigma + systematic of the FERMI GBM final error box (Stanbro et. al. 
GCN 18570) with upper limit up to 19 mag during this night.
The coverage map is available here:

http://master.sai.msu.ru/static/GRB/GRB151107B.png

There is 1 possible OTs was found up to now  - 
MASTER OT J015539.85+485955.6   published yesterday 
(Shumkov et al., Atel #8262).
(RA, Dec) = 01h 55m 39.85s +48d 59m 55.6s

The OT mag is 15.2 on 2015-11-07.99775 UT. The 
specrtrum was done by follow up Liverpool Telescope
(La Palma) observations shows a broad continuum, consistent with
that expected from a dwarf nova in outburst ( Piascik & Steele, ATel #8265). 
The brightness is not sufficiantly changed after half of the day (during 
independently ASAS detection Holoin et al., ATEL #8260) and our today 
imaging (2015-11-10 17:16:26.513UT, m_OT=15.5+-0.1) shows that OT doesn't 
fade essntially with respect to discovery  magnitude contraverse to GRB 
optical afterglow .

The search is continuing.


The message may be cited.


GRB_name: GRB151107B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18577
SUBJECT: IPN triangulation of GRB151107B
DATE:    15/11/11 00:48:21 GMT
FROM:    Kevin Hurley at UCBerkeley/SSL  <khurley@ssl.berkeley.edu>

K. Hurley, on behalf of the IPN,

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

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

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

report:

GRB 151107B (Stanbro and Meegan, GCN 18570) was also observed by Konus-Wind
and Mars Odyssey-HEND.  We have triangulated it to a preliminary annulus centered
at RA, Dec(2000) = 357.447, -2.630, whose radius is 55.156 +/- 0.054 degrees
(3 sigma).  The minimum distance between the center line of this annulus 
and the MASTER-NET optical transient (Lipunov et al., GCN 18576) is 3.22
degrees, supporting the conclusion that the OT and the GRB are indeed unrelated.
A map has been posted at ssl.berkeley.edu/ipn3/151107B.


GRB_name: GRB151111A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18578
SUBJECT: GRB 151111A: Swift detection of a burst
DATE:    15/11/11 08:53:58 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

L. M. McCauley (PSU), P. A. Evans (U Leicester),
H. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 08:33:23 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151111A (trigger=663074).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 56.828, -44.164 which is 
   RA(J2000) = 03h 47m 19s
   Dec(J2000) = -44d 09' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single FRED-like
structure with a duration of about 40 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 08:34:35.8 UT, 72.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
56.8452, -44.1615 which is equivalent to:
   RA(J2000)  = 03h 47m 22.86s
   Dec(J2000) = -44d 09' 41.3"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 45 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 (1.07 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.6
(+1.82/-1.61) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.85e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 81 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 L. M. McCauley (marissamc 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: GRB151111A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18579
SUBJECT: GRB 151111A: Enhanced Swift-XRT position
DATE:    15/11/11 13:39:52 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 639 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 151111A, 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 = 56.84455, -44.16154 which is equivalent
to:

RA (J2000): 03h 47m 22.69s
Dec (J2000): -44d 09' 41.5"

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: GRB151111A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18580
SUBJECT: GRB 151111A: Swift-BAT refined analysis
DATE:    15/11/11 14:23:50 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
L. M. McCauley (PSU), 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 151111A (trigger #663074)
(McCauley, et al., GCN Circ. 18578).  The BAT ground-calculated position is
RA, Dec = 56.850, -44.154 deg which is
    RA(J2000)  =  03h 47m 24.0s
    Dec(J2000) = -44d 09' 12.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.

The mask-weighted light curve shows a single long FRED-shaped peak beginning at 
T-5 sec, peaking at T+0 sec and fading to background by T+140 sec.
T90 (15-350 keV) is 76.93 +- 12.59 sec (estimated error including systematics).

The time-averaged spectrum from T-5.62 to T+91.35 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.79 +- 0.45,
and Epeak of 56.6 +- 9.2 keV (chi squared 98.19 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.7 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+0.52 sec in the 15-150 keV band is
1.0 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.76 +- 0.00 (chi squared 115.24 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/663074/BA/


GRB_name: GRB151111A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18581
SUBJECT: GRB 151111A: LCOGT-FTS afterglow observations
DATE:    15/11/11 17:05:15 GMT
FROM:    Simone Dichiara at Ferrara U/Italy  <dichiara@fe.infn.it>

S. Dichiara (U. Ferrara, ICRANet), C. Guidorzi (U. Ferrara),
S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of a
larger collaboration report:

The 2-m LCOGT Faulkes Telescope South began observing Swift
GRB 151111A (McCauley et al. GCN 18578) on November 11, 10:45 UT
(2.2 hours after the burst trigger) with SDSS R and I filters
under poor sky conditions. We do not detect any optical afterglow
candidate within the enhanced Swift-XRT error circle
(Goad et al. GCN 18579) with the following magnitudes:

Mid Time      Exposure       Filter       Magnitude
(hours)           (s)
-------------------------------------------------------
3.5            10x120         R           > 20.5
4.2             9x120         I           > 20.0
-------------------------------------------------------

Calibration is done against nearby USNOB-1 stars using R2 and I
nominal magnitudes.
We note in both filters the presence of a possible source of
R~21 mag at the following position: RA(J2000)=03:47:22.75,
DEC(J2000)=-44:09:43.6 (error radius of 1.5"). We caution that
the detection is not significant, so we cannot rule out the
possibility that it is a fluke.


GRB_name: GRB151111A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18582
SUBJECT: GRB 151111A: Fermi GBM observation
DATE:    15/11/11 21:23:12 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E.Bissaldi (INFN Bari) and P.N. Bhat (UAH)
report on behalf of the Fermi GBM Team:


"At 08:33:20.03 UT on 11 November 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151111A (trigger 468923604 / 151111356),
which was also detected by the Swift/BAT
(McCauley et al. 2015, GCN 18578).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees.
The GBM light curve consists of a single FRED-like episode
with a duration (T90) of about 40 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+30 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is 0.0  0.2 and
the cutoff energy, parameterized as Epeak, is 107  8 keV.

The event fluence (10-1000 keV) in this time interval is
(2.05  0.13)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.2 s in the 10-1000 keV band
is 1.41  0.17 ph/s/cm^2.


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


GRB_name: GRB151111A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18583
SUBJECT: GRB 151111A: Swift-XRT refined Analysis
DATE:    15/11/12 00:11:28 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), T.G.R. Roegiers (PSU), S.L. Gibson (U. Leicester),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and L.M. McCauley
report on behalf of the Swift-XRT team:

We have analysed 16 ks of XRT data for GRB 151111A (McCauley et al. GCN
Circ. 18578), from 63 s to 45.5 ks after the  BAT trigger. The data
comprise 284 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. 18579).

The late-time light curve (from T0+5.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.2 (+/-0.4).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.28 (+/-0.05). The
best-fitting absorption column is  3.7 (+1.9, -1.7) x 10^20 cm^-2, in
excess of the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.74 (+0.19, -0.18)
and a best-fitting absorption column of 5.0 (+4.8, -3.9) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.7 x 10^-11 (4.1 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.0 (+4.8, -3.9) x 10^20 cm^-2
Galactic foreground: 1.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.74 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
1.2, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.8 x
10^-14 (8.4 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/00663074.

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


GRB_name: GRB151111A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18585
SUBJECT: GRB 151111A: GROND marginal detection of a afterglow candidate
DATE:    15/11/12 04:42:46 GMT
FROM:    John Graham at MPE/Garching  <graham@mpe.mpg.de>

J. F. Graham, T. Schweyer, and J. Greiner (all MPE Garching) report:

We observed the field of GRB 151111A (Swift trigger 663074; Page et al., GCN 18578) 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 00:08:05 UT on November 12, about 16 hours after the GRB trigger. Consistent with the enhanced X-ray error circle (Evans et al., GCN 18579) and the LCOGT-FTS possible source (Dichiara et al., GCN 18581) we detect a faint source at coordinates RA, DEC (J2000) = 03:47:22.73, -44:09:43.3 with an error of 2".

Due to high winds we were able to observe the target for only a limited period in conditions of extremity poor seeing (~3") and thick cirrus.  We thus give the following preliminary AB magnitudes with statistical and estimated systematic errors.

g: 23.25 Â± 0.21 Â± 1.0
r: 22.16 Â± 0.14 Â± 0.5
i: 20.89 Â± 0.15 Â± 0.5

At present we cannot decide if this is the afterglow.  Further observations are currently precluded by high winds.  We encourage additional observations from locations with better observing conditions.

Magnitudes are calibrated against the USNO-B1.0 catalog and are not corrected for the Galactic extinction in the direction of the burst.


GRB_name: GRB151111A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18587
SUBJECT: GRB 151111A: Swift/UVOT upper limits
DATE:    15/11/12 13:57:55 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <m.depasquale@ucl.ac.uk>

M. De Pasquale, S. Emery (UCL-MSSL) and L. M. McCauley (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151111A
81 s after the BAT trigger (McCauley et al., GCN Circ. 18578).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 18579) 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            81           231          147 >20.9
u_FC                293           543          246 >19.7
white                 81         6778          519 >21.7
v                      622         7094          339 >19.7
b                      549         6573          235 >20.6
u                      293         6367          442 >19.7
w1                    671         6163          216 >20.0
m2                 5757         5957          197 >19.7
w2                   772         6984          413 >20.6

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: GRB151112A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18588
SUBJECT: GRB 151112A: Swift detection of a burst
DATE:    15/11/12 13:59:01 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL),
K. L. Page (U Leicester), T. G. R. Roegiers (PSU) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 13:44:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151112A (trigger=663179).  Swift did not slew immediately 
to the burst. The BAT on-board calculated location is 
RA, Dec 2.045, -61.692 which is 
   RA(J2000) = 00h 08m 11s
   Dec(J2000) = -61d 41' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a FRED-shaped 
profile with superimposed peaks and total duration of about 20 sec.  
The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+50.8
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB151112A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18589
SUBJECT: GRB 151112A: Swift-XRT observations
DATE:    15/11/12 15:25:07 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), J.A. Kennea (PSU), M. Perri (ASDC), G. Tagliaferri
(INAF-OAB), P.A. Evans (U. Leicester) and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 151112A at 14:37:09.1 UT,
3141.0 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 2.05651, -61.66273
which is equivalent to:
   RA(J2000)  = 00h 08m 13.56s
   Dec(J2000) = -61d 39' 45.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 107 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 (1.92 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3
(+2.37/-2.09) x 10^21 cm^-2 (90% confidence). 


GRB_name: GRB151112A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18590
SUBJECT: GRB 151112A: initial UVOT observations
DATE:    15/11/12 15:35:21 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC, UCL-MSSL) reports on behalf of the UVOT team:

UVOT took a finding chart exposure of GRB 151112A, 150 seconds with the White filter
starting 3144 seconds after the BAT trigger (Malesani et al., GCN Circ. 18588). 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 (Burrows et al., GCN Circ. 18589). 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. 


GRB_name: GRB151112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18591
SUBJECT: GRB 151112A: MASTER-NET  optical limit
DATE:    15/11/12 19:29:37 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.Shumkov, N.Tyurina, V.Kornilov, P.Balanutsa,
A.Kuznetsov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institute

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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

O.Gress, K.Ivanov, N.M.Budnev, V.A.Poleshchuk
Irkutsk State University

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

V.Krushinski, I.Zalozhnih
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-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  GRB151112A at 2015-11-12 18:12:09 UT 
(~5.5 hours ater trigger). 
On our first (180s exposure)  set we did not  find optical transient within 
Swift error-box (Malesani et al., GCN #18588; Burrows et al., GCN #18589; ) 
brighter then 20.5.

The message may be cited.


GRB_name: GRB151112A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18592
SUBJECT: GRB 151112A: Enhanced Swift-XRT position
DATE:    15/11/12 21:18:52 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 4055 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 151112A, 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 = 2.05348, -61.66328 which is equivalent
to:

RA (J2000): 00h 08m 12.84s
Dec (J2000): -61d 39' 47.8"

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: GRB151112A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18593
SUBJECT: GRB 151112A: Swift-BAT refined analysis
DATE:    15/11/12 22:26:38 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.krimm@nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI),
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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151112A (trigger #663179)
(Malesani, et al., GCN Circ. 18588).  The BAT ground-calculated position is
RA, Dec = 2.050, -61.680 deg which is
    RA(J2000)  =  00h 08m 11.9s
    Dec(J2000) = -61d 40' 46.7"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 52%.

The mask-weighted light curve shows several overlapping peaks, starting with a 
sharp rise peaking at T=0 sec, then a second peak at T+5 sec, a third at T+10 
sec and falling to background by T+20 sec. T90 (15-350 keV) is 19.32 +- 31.24 
sec (estimated error including systematics).

The time-averaged spectrum from T-0.06 to T+61.94 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.77 +- 0.21.  The fluence in the 15-150 keV band is 9.4 +- 1.2 x 10^-7 erg/cm2. 
The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 
1.9 +- 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/663179/BA/


GRB_name: GRB151112A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18594
SUBJECT: GRB 151112A: Swift-XRT refined Analysis
DATE:    15/11/13 01:12:59 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'ai (INAF-IASFPA), J.A.
Kennea (PSU) and D. Malesani report on behalf of the Swift-XRT team:

We have analysed 9.6 ks of XRT data for GRB 151112A (Malesani et al.
GCN Circ. 18588), from 3.1 ks to 33.0 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Osborne et al. (GCN Circ. 18592).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.43 (+/-0.08).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.21 (+0.17, -0.16). The
best-fitting absorption column is  1.1 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.9 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 3.0 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.1 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:      2.21 (+0.17, -0.16)

If the light curve continues to decay with a power-law decay index of
0.43, the count rate at T+24 hours will be 0.040 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-12 (1.6 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/00663179.

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


GRB_name: GRB151112A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18595
SUBJECT: GRB 151112A: GROND Detection of the Optical/NIR Afterglow Candidate
DATE:    15/11/13 01:27:10 GMT
FROM:    Fabian Knust at MPE/GROND  <fknust@mpe.mpg.de>

F. Knust, T.-W. Chen and J. Greiner (all MPE Garching) report on behalf of
the GROND team:

We observed the field of GRB 151112A (Swift trigger 663179; Malesani et
al., GCN #18588) 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 the ESO La
Silla Observatory (Chile).

Observations started at 00:09 UT on 2015-11-13, 10.5hrs after the GRB
trigger, and are continuing. They were performed at an average seeing of
1.8" and at an average airmass of 1.2.

We found a single point source within the 1.4" Swift-XRT error circle
reported by Osborne et al. (GCN #18592) at

RA (J2000) = 00h 08m 12.77s

DEC (J2000) = -61d 39' 48.4"

with an uncertainty of 0.5" in each coordinate.

Based on 11.50 min of total exposures in g'r'i'z' and 12.00 min in JHK, we
estimate preliminary magnitudes (all in AB system) of

g' > 23.9 mag,
r' = 23.9 +/- 0.373 mag,
i' = 22.4 +/- 0.169 mag,
z' = 22.5 +/- 0.288 mag,
J  > 21.0 mag,
H  > 20.5 mag, and
K  > 19.0 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)=0.01 mag in the
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB151112A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18596
SUBJECT: GRB 151112A: MAXI/GSC detection
DATE:    15/11/13 01:34:09 GMT
FROM:    Satoshi Nakahira at JAXA/MAXI  <nakahira.satoshi@jaxa.jp>

K. Yamaoka (Nagoya U.), H. Negoro, T. Masumitsu (Nihon U.),
S. Ueno, H. Tomida, S. Nakahira, 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, 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 13:45:24 UT. Assuming that the source flux was constant over the transit,
we obtain the source position at

(R.A., Dec) = (1.543 deg, -61.934 deg) = (00 06 10, -61 56 03) (J2000)

with a 90% C.L. statistical error of 0.25 deg and an additional systematic uncertainty
of 0.1 deg (90% containment radius).
This position is consistent with Swift GRB 151112A (Malesani et al., GCN Circ. 18588).
The X-ray flux averaged over the scan was 217 +- 31 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at 12:12 UT
and in the next transit at 2015-11-12 15:17 UT with an upper limit of 20 mCrab for each.


GRB_name: GRB151112A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18597
SUBJECT: GRB 151112A: Swift/UVOT Upper Limits
DATE:    15/11/13 11:13:43 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and D. Malesani (DARK/NBI)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151112A
3144 s after the BAT trigger (Malesani et al., GCN Circ. 18588).
No optical afterglow, consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 18592) and the GROND position 
(Knust et al., GCN Circ. 18595), 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          3144         3294          147         >21.3
white             3144         4527          344         >21.8
v                 3301         4938          393         >20.2
b                 4123        10985          349         >21.1
u                 3917        10825         1082         >21.5
w1                3711         9912         1169         >21.4
m2                3506        15760         1240         >21.3

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: GRB151111A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18598
SUBJECT: GRB 151111A: GROND confirmation of the afterglow and photometric redshift estimate
DATE:    15/11/13 18:01:27 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

J. Bolmer, J. Graham, F. Knust and J. Greiner (all MPE Garching) report:

We reobserved the field of GRB 151111A (Swift trigger 663074; Page et al., GCN 18578) simultaneously in gâ€™râ€™iâ€™zâ€™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 05:31:33 UT on November 13, about 1.9 days after the GRB trigger.
The initially reported source at the coordinates of RA, Dec = 56.84483, -44.16201 (+/- 0.2â€œ) (Graham et al. GCN 18585)
has clearly faded (e.g. in the râ€™ band from 22.19 +/- 0.04 to 22.68 +/- 0.05 mag) and we thus conclude that this source is the optical afterglow of GRB 151111A.

Furthermore, after correcting for the galactic foregorund E(B-V)=0.01 mag, and
fitting a powerlaw model to the 7-cannel GROND SED from the first night,
we derive a photometric redshift of z = 3.5 +/- 0.3, according to the g'-band dropout
with g'-râ€™ =  1.3 mag.


GRB_name: GRB151114A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18599
SUBJECT: GRB 151114A: Swift detection of a burst with an optical counterpart
DATE:    15/11/14 10:12:35 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

M. H. Siegel (PSU), S. D. Barthelmy (GSFC), N. P. M. Kuin (UCL-MSSL),
L. M. McCauley (PSU) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:

At 09:59:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151114A (trigger=663490).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 120.937, -61.042, which is 
   RA(J2000)  =  08h 03m 45s
   Dec(J2000) = -61d 02' 31"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple peaks
with a duration of about 20 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 10:01:03.9 UT, 89.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 120.94436, -61.02743 which is
equivalent to:
   RA(J2000)  = 08h 03m 46.65s
   Dec(J2000) = -61d 01' 38.7"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 53 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 2.01
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 94 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 08:03:46.33 = 120.94305
  DEC(J2000) = -61:01:40.0  = -61.02779
with a 90%-confidence error radius of about 0.63 arc sec. This position is 1.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.84 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.17. 

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: GRB151114A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18600
SUBJECT: GRB 151114A: Enhanced Swift-XRT position
DATE:    15/11/14 13:56:04 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 1128 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151114A, 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 = 120.94305, -61.02792 which is equivalent
to:

RA (J2000): 08h 03m 46.33s
Dec (J2000): -61d 01' 40.5"

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: GRB151114A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18601
SUBJECT: GRB 151114A: LCOGT-FTS afterglow observations
DATE:    15/11/14 18:33:47 GMT
FROM:    Simone Dichiara at Ferrara U/Italy  <dichiara@fe.infn.it>

S. Dichiara  (U. Ferrara, ICRANet), C. Guidorzi (U. Ferrara),
A. Melandri (INAF-OAB), C.G. Mundell (U. Bath), S. Kobayashi (LJMU),
A. Gomboc (U. Ljubljana) on behalf of a large collaboration report:

The 2-m Faulkes Telescope South began observing Swift GRB 151114A
(Siegel et al. GCN 18599) on November 14, 12:18:07 UT (~2.3 hours after
the BAT trigger) with SDSS R and I filters.

we identify the optical afterglow (Siegel et al. GCN 18599) in the R
filter with R = 20.6 +/- 0.2 mag at a mid time of 2.64 hours post burst
(total exposure 600 s). The counterpart is detected also visible in
the I-band image.
Data reduction and calibration continue. The magnitude is calibrated
against nearby USNOB-1 stars (R2).


GRB_name: GRB151114A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18602
SUBJECT: GRB 151114A: Swift/UVOT Detection
DATE:    15/11/14 19:34:41 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and M. H. Siegel (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151114A
95 s after the BAT trigger (Siegel et al., GCN Circ. 18599).
A source consistent with the XRT position
(Siegel et al. GCN Circ. 18599)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  08:03:46.33 = 120.94306 (deg.)
    Dec (J2000) = -61:01:40.0  = -61.02779 (deg.)
with an estimated uncertainty of 0.45 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               95          244          147         18.61 +/- 0.06
v                  638         1233           72        >18.4
b                  563         1164           58         19.45 +/- 0.26
u                  307          557          246         18.46 +/- 0.09
w1                 688         1115           39        >18.3
m2                 662         1090           58        >19.2
w2                 613         1215           78        >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151112A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18603
SUBJECT: GRB 151112A: GROND photometric redshift and i'-band prediction
DATE:    15/11/14 20:28:01 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

J. Bolmer, F. Knust and J. Greiner (all MPE Garching) report on behalf
of the GROND team: 

We present further analysis of the GROND observations of GRB 151112A 
(Swift trigger 663179; Malesani et al., GCN #18588; Knust et al. GCN
#18595). 

After correcting for the galactic foreground E(B-V)=0.01 mag and 
fitting a power-law model to the 7-channel GROND SED from the first
night, 
we derive a photometric redshift of z = 4.1 +/- 0.3, according to the
g'- and r'-band 
dropouts with g'-r' > 1.5 mag and r'-i' = 0.9 mag. 

Based on the observed decay between the first and the second night we
predict an 
i'-band magnitude of ~24 mag for the coming night. 
 


GRB_name: GRB151114A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18604
SUBJECT: GRB 151114A: Swift-BAT refined analysis
DATE:    15/11/14 20:49:26 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), 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-240 to T+962 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 151114A (trigger #663490)
(Siegel, et al., GCN Circ. 18599).  The BAT ground-calculated position is
RA, Dec = 120.947, -61.033 deg, which is 
   RA(J2000)  =  08h 03m 47.4s 
   Dec(J2000) = -61d 01' 58.3" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.
 
The mask-weighted light curve shows a single peak starting at ~T-4 sec,
peaking at ~T0 sec, and ending at ~T+1 sec.  T90 (15-350 keV) is
4.86 +- 0.98 sec (estimated error including systematics).
 
The time-averaged spectrum from T-4.26 to T+1.25 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.14 +- 0.25.  The fluence in the 15-150 keV band is 3.7 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.06 sec in the 15-150 keV band
is 2.9 +- 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/663490/BA/


GRB_name: GRB151107B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18605
SUBJECT: GRB 151107B: CALET Gamma-Ray Burst Monitor detection
DATE:    15/11/15 00:45:59 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

The long-duration GRB 151107B (Stanbro et al. GCN Circ. 18570) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 20:24:54.77 UT on 7 November 2015.  The burst 
was detected by all three CGBM instruments.  Based on the signal-to-noise among the 
instruments, the incident angle of the burst was estimated as ~40-70 deg from the zenith 
direction of CGBM.  This estimated incident angle is roughly consistent with the IPN 
triangulation (Hurley et al., GCN Circ. 18577).

The light curve of the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) shows the main 
peak starting from T0-5 sec, peaking at T0+5 sec and ending at T0+~30 sec.  The 
second weak peak starts from T0+90 sec, peaks at T0+95 sec and ends at T0+100 sec.  
The T90 duration measured by the SGM data is 95.0 +- 1.4 s (40-920 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm


GRB_name: GRB151114A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18606
SUBJECT: GRB 151114A: Swift-XRT refined Analysis
DATE:    15/11/15 10:12:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.1 ks of XRT data for GRB 151114A (Siegel et al. GCN
Circ. 18599), from 97 s to 48.6 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Beardmore et al. (GCN Circ. 18600).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.73 (+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 2.00 (+0.16, -0.12). The
best-fitting absorption column is  consistent with the Galactic value
of 2.0 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.0 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.00 (+0.16, -0.12)

If the light curve continues to decay with a power-law decay index of
0.73, the count rate at T+24 hours will be 8.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x
10^-13 (3.8 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/00663490.

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


GRB_name: GRB151114A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18607
SUBJECT: GRB 151114A: GROND Detection of the Optical/NIR Afterglow Candidate
DATE:    15/11/15 16:10:09 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

J. Bolmer, F. Knust and J. Greiner (all MPE Garching) report on behalf of
the GROND team:

We observed the field of GRB 151114A (Swift trigger 663490; Siegel et
al., GCN #18599) 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 the ESO La
Silla Observatory (Chile).

Observations started at 04:59 UT on 2015-11-15, 19.5hrs after the GRB
trigger. They were performed at an average seeing of
1.8" and at an average airmass of 1.5.

We found a single point source within the 1.8" Swift-XRT and 0.45" Swift-UVOT error
circles reported by Beardmore et al. (GCN #18600) and Kuin et al. (GCN #18602) at
RA, Dec = 120.94299, -61.02778

RA (J2000) = 08h 03m 46.32s
DEC (J2000) = -61d 01' 40.0"

with an uncertainty of 0.3" in each coordinate.

Based on 25.2 min of total exposures in g'r'i'z' and 25.5 min in JHK, we
estimate preliminary magnitudes (all in AB system) of

g' = 23.7 +/- 0.3 mag,
r' = 23.2 +/- 0.2 mag,
i' = 23.1 +/- 0.3 mag,
z' = 23.3 +/- 0.4 mag,
J  > 21.4 mag,
H  > 20.9 mag, and
K  > 19.5 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)=0.17 mag in the
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB151027A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18608
SUBJECT: GMRT radio detection of GRB 151027A
DATE:    15/11/16 11:43:16 GMT
FROM:    Poonam Chandra at TIFR  <poonam@ncra.tifr.res.in>

Poonam Chandra (NCRA-TIFR) and A. J. Nayana (NCRA-TIFR) reports:

We carried out Giant Metrewave Radio Telescope (GMRT) observations of
GRB 151027A (GCN Circ. 18478) at 1390 MHz band on 2015 Nov 15.19 UT. We
detect the  radio afterglow of the GRB in the Swift error circle (GCN 
Circ. 18482).
The 1390 MHz band flux density of the afterglow is 312+/-64 uJy. Map rms is
37 uJy.

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

-- 
_________________________________________
Poonam Chandra
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Pune University Campus, Ganeshkhind
Pune 411007, Maharashtra, INDIA
Phone: +91 20 2571 9290
Fax:   +91 20 2569 7257
Email: poonam@ncra.tifr.res.in
Web:   www.ncra.tifr.res.in:8081/~poonam/
_________________________________________


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18609
SUBJECT: GRB151027A; Optical observations
DATE:    15/11/16 12:16:29 GMT
FROM:    G.C. Anupama at IIA,Bangalore  <gca@iiap.res.in>

We observed the field of GRB 151027A (Maselli et al., GCN 18478) using
the 2m Himalayan Chandra Telescope of Indian Astronmical Observatory, 
Hanle,
India.  The GRB field was observed in Bessells R band, during 14:56 UT 
to
16:20 UT on 2015-10-27. We obtained 20 frames, each  of 150 seconds
exposure time.  The optical afterglow of  GRB 151027A (e.g., Maselli et 
al.,
GCN 18478; Zheng & Filippenko, GCN  18479; Elenin et al., GCN 18480;
Perley & Cenko, GCN 18481)  is clearly detected in each image. The
measured magnitudes, calibrated using nearby  USNO B1.0 (R2 magnitudes)
stars are listed below.

---------------------------------------------------------------------
Time (UT start)        Filter       Mag    error
14:56                R          16.60   0.06
15:36                R          16.67   0.07
16:20                R          16.86   0.08
-----------------------------------------------------------------------

This message may be cited.

D.K. Sahu and G.C. Anupama (Indian Institute of Astrophysics, Bengaluru)


GRB_name: GRB151118A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18611
SUBJECT: GRB 151118A: Swift detection of a burst
DATE:    15/11/18 03:24:39 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of
the Swift Team:

At 03:06:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151118A (trigger=664078).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 57.158, +65.869, which is 
   RA(J2000)  =  03h 48m 38s
   Dec(J2000) = +65d 52' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a few peaks
with a duration of about 25 sec.  The peak count rate
was ~2600 counts/sec (15-350 keV), at ~6 sec after the trigger. 

The XRT began observing the field at 03:07:36.2 UT, 66.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 57.1719,
65.9012 which is equivalent to:
   RA(J2000)  = 03h 48m 41.25s
   Dec(J2000) = +65d 54' 04.4"
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This
location is 117 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 (4.54 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 5.9
(+4.29/-3.55) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
281 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 18.0 mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 1.10. 

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: GRB151118A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18612
SUBJECT: GRB 151118A: Optical observations from OSN
DATE:    15/11/18 04:36:51 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), A. Sota (IAA-CSIC), 
and C. Thoene (IAA-CSIC) report:

We observed the field of GRB 151118A (Amaral-Rogers et al. GCN 18611) 
with the 1.5 m OSN telescope in Granada (Spain), starting at 03:17:55 UT 
(11.42 min after the GRB onset). Observations consisted of 7x300 s 
exposures in I-band. No new source is detected within the XRT error box. 
The 3-sigma limiting magnitudes of the individual exposures, and the combined
frames are I(Vega) = 21.5 mag, and I(Vega) = 22.5 mag, respectively. The mean
time of the combined exposure is 03:37:49 (31.32 min after the burst). Photometry
was obtained by comparison with stars from the USNO-B1.0 catalogue.


GRB_name: GRB151118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18613
SUBJECT: GRB GRB 151118A: MASTER-NET  optical observations
DATE:    15/11/18 11:11:38 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB151118.13 30 sec after notice 
time and 44 sec after trigger time at 2015-11-18 03:07:17 UT. On our first 
(10s exposure)  set we haven't found optical transient  within SWIFT 
error-box (ra=03 48 37 dec=+65 52 06 r=0.05).
The 5-sigma upper limit has been about 16.5  mag unfiltered.

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was pointed to the  GRB151118A  24 sec after notice time 
and 42 sec after trigger time at 2015-11-18 03:07:12 UT in two 
polarizations. On our first (10s exposure)  set we haven't found optical 
transient  within SWIFT error-box (Amaral-Rogers et al GCN 18611).
Our early upper limits on single and coadd images given in a table below:

Table 1.
5 sigma limit.

T-Ts  T-Tm  Expt.    P|     P-    coadd.
                     lim     lim 
----------------------------------------
   42    47    10    16.7   16.8     1
   42    90    50    17.9   18.0     3
   42   508   790    19.9   20.0    12
   86    96    20    17.3   17.4     1
  117   127    20    17.3   17.4     1
  147   218   120    18.7   18.8     3
  299   420   220    19.2   19.3     3
  551   762   400    19.6   19.7     3
---------------------------------------

  T   - is a trigger time [s].
Ts   - image start time [s].
Tm   - image middle time [s].
Expt - exposure time [s].
P|   - image upper limit in polarizer orientated 90 deg. to RA axis [mag].
P-   - image upper limit in polarizer orientated  0 deg. to RA axis [mag].

We do not see OT brighter 20 mag. There is marginal object (m~20) with 6" 
W (RA) and 3"S (dec)  offset from XRT error box center (Ra = 03h 48m 
40.40s Dec= 65d 54m 01.3s Mag ~ 20.3 +- 0.7  ).

The message may be cited.


GRB_name: GRB151118A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18614
SUBJECT: GRB 151118A: Enhanced Swift-XRT position
DATE:    15/11/18 11:22:15 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 4427 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 151118A, 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 = 57.17172, +65.90168 which is equivalent
to:

RA (J2000): 03h 48m 41.21s
Dec (J2000): +65d 54' 06.1"

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: GRB151118A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18615
SUBJECT: GRB 151118A: Swift/UVOT Upper Limits
DATE:    15/11/18 12:31:35 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and Amaral-Rogers (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151118A
70 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 18611).
No optical afterglow consistent with the XRT position
(Amaral-Rogers et al. GCN Circ. 18611)
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)           70          220          148         >20.6
u (fc)              282          532          246         >20.0
white               70          754          186         >20.8
v                  612          631           19         >18.3
b                  537          730           39         >19.3
u                  282          705          265         >19.9
w1                 661          680           19         >18.2
w2                 587          607           19         >17.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.10 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151027A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18616
SUBJECT: GRB 151027A: SAO RAS and Mt. Terskol observations
DATE:    15/11/18 12:41:05 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin (SAO RAS), I. V. Sokolov (Terskol Branch of INASAN)
report on behalf of larger GRB follow-up team.

We observed the field of GRB 151027A twice: with 2-m Zeiss-2000
+ FLI CCD (Mt. Terskol) and 1-m Zeiss-1000 + EEV 42-40 CCD (SAO RAS)
on November 6 and 12 respectively (T-T0 = 10.5 and 16.5 days).

We have obtained 10x300 and 24x300 sec. frames in R band.
We do not detect the GRB OT (Maselli et al., GCNC #18478)
down to the limiting magnitude R_lim = 22.8 in both stacked images.
As the standard stars we used USNO-B1 objects from GCNCs #18521,
18558 and 18559.

We should note that nearby USNO-B1 source reported by
S. Dichiara et al. (GCNC #18510) and E. Mazaeva et al. (GCNC #18559)
is clearly detected in our images.


GRB_name: GRB151118A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18617
SUBJECT: GRB 151118A: Swift-XRT refined Analysis
DATE:    15/11/18 12:44:51 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 7.4 ks of XRT data for GRB 151118A (Amaral-Rogers et
al. GCN Circ. 18611), from 52 s to 22.7 ks after the  BAT trigger. The
data comprise 22 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 Evans
et al. (GCN Circ. 18614).

The late-time light curve (from T0+4.9 ks) can be modelled with a
power-law decay with a decay index of alpha=1.07 (+/-0.26).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.93 (+0.23, -0.22). The
best-fitting absorption column is  1.07 (+0.25, -0.21) x 10^22 cm^-2,
in excess of the Galactic value of 4.5 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.1 x 10^-11 (9.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.07 (+0.25, -0.21) x 10^22 cm^-2
Galactic foreground: 4.5 x 10^21 cm^-2
Excess significance: 4.7 sigma
Photon index:      1.93 (+0.23, -0.22)

If the light curve continues to decay with a power-law decay index of
1.07, the count rate at T+24 hours will be 4.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x
10^-13 (4.2 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/00664078.

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


GRB_name: GRB151118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18618
SUBJECT: GRB 151118A: ISON-NM early optical limit
DATE:    15/11/18 14:44:20 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

L. Elenin (KIAM),  A. Volnova (IKI), E. Mazaeva (IKI),  I. Molotov 
(KIAM), A. Pozanenko (IKI) report on behalf of larger GRB  follow-up 
collaboration:

We observed the field of the Swift GRB 151118A (Amaral-Rogers et  al., 
GCN 18611) with 0.4-m telescope of ISON-NM observatory in robotic mode 
starting on Nov., 18 (UT) 03:08:32  i.e. 122 seconds after burst 
trigger. We obtained 6 unfiltered images of 30 s exposure under 
unfavorable weather conditions. We do not detect any source within 
enhanced XRT error circle (Evans et al., GCN 18614):

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

2015-11-28 03:08:32   0.00158  None    1*30   17.4
2015-11-28 03:08:32   0.00265  None    5*30   18.0

The photometry is based on nearby USNO-B1.0 stars:
USNO-B1.0 id R2
1559-0079254 15.66
1558-0078601 16.03
1558-0078636 14.62


GRB_name: GRB151118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18619
SUBJECT: GRB 151118A: Early optical limit from pt5m, La Palma
DATE:    15/11/18 17:56:51 GMT
FROM:    Liam K Hardy at U of Shffield  <liam.hardy@sheffield.ac.u>

L. K. Hardy (Sheffield), V. S. Dhillon (Sheffield, IAC),
S. P. Littlefair (Sheffield), T. Butterley (Durham) and
R. W. Wilson (Durham) report:

Our automated robotic telescope 'pt5m' (Hardy et al. 2015, MNRAS 454,
4316) on La Palma observed the field of
GRB 151118A (Amaral-Rogers et al., GCN 18611) starting
at 03:16:27 UT on Nov 18, 10 min after the GRB detection.

Observations comprised of 46 x 60-second exposures in
the R-band. We detect no new source within the XRT error box (Evans et
al., GCN 18614). The 3-sigma limiting magnitude of
a combined image is R = 22.1 mag. The mean time of the
combined exposure is 03:42 UT (36 mins after the burst).
We obtained photometry using the nearest comparison star,
USNOB1.0:1559-0079286, R=15.6.


GRB_name: GRB151027A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18620
SUBJECT: 610 MHz detection of GRB 151027A with the GMRT
DATE:    15/11/19 10:52:47 GMT
FROM:    Poonam Chandra at TIFR  <poonam@ncra.tifr.res.in>

Poonam Chandra (NCRA-TIFR) and A. J. Nayana (NCRA-TIFR) reports:

We carried out Giant Metrewave Radio Telescope (GMRT) observations of
GRB 151027A (GCN Circ. 18478) at 610 MHz band on 2015 Nov 19.19 UT. We
detect the  radio afterglow of the GRB in the Swift error circle (GCN 
Circ. 18482).
The 610 MHz band flux density of the afterglow is 522+/-94 uJy. Map rms is
56 uJy.

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

-- 
_________________________________________
Poonam Chandra
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Pune University Campus, Ganeshkhind
Pune 411007, Maharashtra, INDIA
Phone: +91 20 2571 9290
Fax:   +91 20 2569 7257
Email: poonam@ncra.tifr.res.in
Web:   www.ncra.tifr.res.in:8081/~poonam/
_________________________________________


GRB_name: GRB151118A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18622
SUBJECT: GRB 151118A, Swift-BAT refined analysis
DATE:    15/11/20 00:36:34 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC),
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-239 to T+941 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151118A (trigger #664078)
(Amaral-Rogers, et al., GCN Circ. 18611).  The BAT ground-calculated position is
RA, Dec = 57.169, 65.889 deg which is
  RA(J2000)  =  03h 48m 40.6s
  Dec(J2000) = +65d 53' 22.0"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~ T0 and ends at ~T+30 s. The structure contains roughly two main
pulses that peak at ~ T0 and ~T+7 s, respectively. T90 (15-350 keV) is
23.4 +- 10.5 sec (estimated error including systematics).

The time-averaged spectrum from T+0.0 to T+30.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.20.  The fluence in the 15-150 keV band is 4.5 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+6.41 sec in the 15-150 keV band
is 1.2 +- 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/664078/BA/


GRB_name: GRB151120A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18623
SUBJECT: GRB 151120A: A long GRB detected by INTEGRAL
DATE:    15/11/20 09:23:58 GMT
FROM:    Sandro Mereghetti at IASF/CNR  <sandro@iasf-milano.inaf.it>

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

a gamma ray burst lasting about 50 s has been detected by IBAS in the 
IBIS/ISGRI data at 8:22:50 UT of 2015 November 20.

The refined coordinates (J2000) are:

R.A.=  157.2502 deg
DEC.=  -32.5237 deg

with an uncertainty of   1.5   arcmin (90% c.l.).

The burst saturated the available ISGRI telemetry, therefore we can only 
provide a lower limit for the fluence in the 20-200 keV energy range of 
2e-6 erg/cmq.

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


GRB_name: GRB151120A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18624
SUBJECT: GRB 151120A: GROND optical/NIR afterglow
DATE:    15/11/20 09:58:39 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>

T. Kruehler, J. Greiner, J. Ridl (all MPE) and A. Hempel (Universidad 
Andres Bello) report on behalf of a larger collaboration:

We observed the field of GRB 151120A (INTEGRAL trigger 7295; Mereghetti
et al., GCN #18623) simultaneously in grizJHK 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 November 20, 2015, 08:27 UTC, 4 minutes after
the GRB trigger. They were performed at an average seeing of 1.3" and
at an average airmass of 1.2.

Inside the INTEGRAL error circle (Mereghetti et al., GCN #18623), we 
detect an uncatalogued and variable source, which we consider the 
optical/NIR afterglow of GRB 151120A. The object is at:

RA (J2000): 10:28:57.94
Dec (J2000): -32:31:35.1

with an estimated uncertainty of 0.5" in each coordinate.

Based on 4.4 min of total exposures in griz and 4 min in JHK obtained
at a midtime of 15 minutes after the trigger, we derive preliminary
magnitudes of:

g = 20.0 +- 0.1
r = 19.4 +- 0.1
i = 19.0 +- 0.1
z = 18.8 +- 0.1
J = 18.2 +- 0.1
H = 18.0 +- 0.2
K = 18.0 +- 0.3

These measurements are in the AB system and calibrated against GROND
zero-points in griz as well as 2MASS field stars in JHK. They are not
corrected for the expected Galactic foreground extinction corresponding
to a reddening of E_(B-V)=0.07 mag in the direction of the burst
(Schlafly & Finkbeiner et al. 2011).


GRB_name: GRB151120A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18625
SUBJECT: GRB 151120A: Swift ToO observations
DATE:    15/11/20 12:43:15 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 INTEGRAL GRB 151120A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020559

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 INTEGRAL 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: GRB151118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18627
SUBJECT: GRB 151118A: AAO optical upper limit
DATE:    15/11/20 15:09:39 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), R. Inasaridze (AAO), V. Ayvazian (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 151118A (Amaral-Rogers et  al.,
GCN 18611) with AS-32 (0.7m) telescope of Abastumani Observatory 
starting on Nov. 18 (UT) 18:08:09.  We do not detect any source within
enhanced XRT error circle (Evans et al., GCN 18614):

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

2015-11-18 18:08:09    0.65922  None    35*120   22.1

The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id     R2
1559-0079254 15.66
1559-0079234 16.18
1559-0079286 15.60
1559-0079243 16.15
1558-0078596 14.88


GRB_name: GRB151120A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18628
SUBJECT: GRB 151120A: Fermi GBM observation
DATE:    15/11/20 15:43:09 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

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

"At 08:22:53.70 UT on 20 November 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151120A (trigger 469700577 / 151120349),
which was also detected by the INTEGRAL/ISGRI (Mereghetti et al. 2015, GCN
18623)
The GBM on-ground location is consistent with the INTEGRAL position.

The angle from the Fermi LAT boresight at the GBM trigger time is 65.6
degrees.

The GBM light curve consists of multiple peaks 
with a duration (T90) of about 20 s (50-300 keV).
The time-averaged spectrum from T0+0.003 s to T0+21.760 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.29 +/- 0.03 
and the cutoff energy, parameterized as Epeak, is 243 (+23/-19)keV.

The event fluence (10-1000 keV) in this time interval is
(9.4 +/- 0.3)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+11.9682 s in the 10-1000 keV band
is 7.0 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well with 
Epeak = 217 (+27/-25) keV, alpha = -1.26 +/- 0.04  
and beta = -2.30 (+0.20/-0.40). 

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


GRB_name: GRB151120A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18629
SUBJECT: GRB 151120A: Swift-XRT afterglow detection
DATE:    15/11/20 20:16:45 GMT
FROM:    Sarah Gibson at U.of Leicester  <slg44@leicester.ac.uk>

A.P. Beardmore (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU), T.G.R. Roegiers (PSU), S.L. Gibson (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 INTEGRAL-detected
burst GRB 151120A (Mereghetti et al. GCN Circ. 18623), collecting 3.9
ks of Photon Counting (PC) mode data between T0+16.4 ks and T0+23.6 ks.


An uncatalogued X-ray source is detected inside or close to the
INTEGRAL error region and is above the RASS limit, and is therefore
likely the GRB afterglow.  The position of this source is RA,
Dec=157.2410, -32.5262 which is equivalent to:

RA (J2000): 10:28:57.83
Dec(J2000): -32:31:34.2

with an uncertainty of 3.6 arcsec (radius, 90% confidence).  This
position is 29 arcsec from the INTEGRAL position and 1.6 arcsec from
the afterglow detected by GROND (GCN 18624). 

The light curve can be modelled with a power-law decay with a decay
index of alpha=2.3 (+1.0, -0.9).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+0.31, -0.28). The
best-fitting absorption column is  2.7 (+1.3, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 9.0 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 3.7 x 10^-11 (5.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.7 (+1.3, -1.1) x 10^21 cm^-2
Galactic foreground: 9.0 x 10^20 cm^-2
Excess significance: 2.8 sigma
Photon index:      2.00 (+0.31, -0.28)

If the light curve continues to decay with a power-law decay index of
2.3, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.5 x
10^-14 (1.1 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00020559/index_1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020559.

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


GRB_name: GRB151118A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18630
SUBJECT: GRB 151118A: MITSuME Akeno optical upper limits 
DATE:    15/11/21 08:27:02 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

Y.Yano, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana,
Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)

report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151118A (A. Amaralâ€“Rogers et al., GCN Circular #18611) 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 2015-11-18 19:14:09 UT (~16.1 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
-------------------------------------------------------------
58059  19:44:17  2520  > 20.3  > 19.6  > 18.4
-------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151027A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18635
SUBJECT: GRB 151027A: Maidanak optical observations
DATE:    15/11/22 21:48:09 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI),  O. Burhonov 
(UBAI) report on behalf of larger GRB follow-up collaboration:

We observed the Swift GRB 151027A  (Maselli  et al., GCN 18478)  with 
AZT-22 telescope of Maidanak observatory equipped with SNUCAM in R 
filter. We obtained several images in R-filter on Oct., 30, Nov., 6 and 
  Nov., 9 under mean FWHM of about 0.9".  The afterglow (Maselli et al., 
GCN 18478; Zheng and  Filippenko, GCN 18479) is clearly detected in each 
epoch.  The afterglow is well separated from nearby source  (Dichiara et 
al.GCN 18510; Mazaeva et al., GCN 18559).

Preliminary photometry of the afterglow  is following

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

2015-11-06   15:04:07  10.474   R        10*300   23.30   0.24
2015-11-09   14:06:04  13.443   R        10*300   23.33   0.20

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

USNO-B.1_id  R2
1513-0237223 16.66
1513-0237251 16.81
1513-0237270 16.78

A preliminary light curve of the afterglow can be found in 
http://grb.rssi.ru/GRB151027A/GRB151027A_lc.png

At this time it is unclear what is a reason of flattening of the light 
curve at 11-13 days. It might be SN signature or it is continuing bumps 
of the light curve previously seen at least on ~ 1.3 days and ~3 days.


GRB_name: GRB151120A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18636
SUBJECT: Konus-Wind observation of GRB 151120A
DATE:    15/11/23 10:14:13 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 151120A
(INTEGRAL ISGRI detection: S. Mereghetti et al., GCN Circ. 18623;
Fermi GBM detection: A. von Kienlin, GCN Circ. 18628)
triggered Konus-Wind at T0=30171.357 s UT (08:22:51.357).

The burst light curve shows a multipeaked structure
started at ~T0-1.3 s with a total duration of ~20 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/GRB151120_T30171/

As observed by Konus-Wind, the burst
had a fluence of 7.20(-1.25,+1.79)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.752 s,
of 2.09(-0.88,+1.15)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+24.832 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.26 (-0.48,+0.77),
the high energy photon index beta = -2.70 (-0.88,+0.35),
the peak energy 106 (-19,+20) keV
(chi2 = 84/85 dof)

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = 0.81 (-0.75,+3.91),
the high energy photon index beta = -2.42 (-0.38,+0.35),
the peak energy 113 (-40,+22) keV
(chi2 = 81/82 dof)

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


GRB_name: GRB151122A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18637
SUBJECT: Subject: GRB 151122A: Swift detection of a burst 
DATE:    15/11/23 20:25:59 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

David Palmer reports on behalf of the Swift team:

On November 22, at 17:00:40 UT, BAT rate-triggered and detected a 6.0 sigma 
peak in an image. Because this was below the nominal 6.5 sigma threshold, 
BAT did not trigger a burst response.  However, ground analysis leads us to 
believe that this is a real burst, GRB 151122A (trigger #664653) with an
onboard-calculated location RA,dec = 299.704, -19.899, which is
RA(J2000) = 19h 58m 49s
dec(J2000) = -19d 53â€™ 56â€
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The lightcurve shows a slow-rise, fast decay peak
from T-5 s to T+12 s, following by a possible second lower peak extending
to T+45 s.  The peak count rate was ~1500 counts/sec (15-350 keV), 
at ~6 sec after the trigger.

The peak of this burst was after a pre-planned slew had started, thus
only the initial rise of this burst was imaged on board.  However, the
burst was also seen by Fermi GBM (trigger #469904449) which
gave a final ground-calculated position of RA,dec = 292.950, -21.350
with an 11.1 degree statistical error radius and a 1-sigma location contour
that contains the BAT location.  The GBM lightcurve is also consistent with
the BAT lightcurve.  Therefore we believe that both of these triggers
are the same astrophysical GRB at the location found by BAT

A Target Of Opportunity Swift observation has been accepted for this GRB.


GRB_name: GRB151122A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18638
SUBJECT: GRB 151122A: Swift ToO observations
DATE:    15/11/23 21:43:16 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 ToO observation of the Swift/BAT GRB 151122A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020560

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: GRB151122A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18639
SUBJECT: GRB 151122A: Fermi GBM detection
DATE:    15/11/23 22:45:08 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

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

"At 17:00:45.01 UT on 22 November 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151122A (trigger 469904449 / 151122709)
which was also detected by the Swift/BAT (Palmer et al. 2015, GCN 18637).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 51 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 30 s (50-300 keV).
The time-averaged spectrum from T0-4.10 s to T0+29.70 s is
best fit by a simple power law function with index -2.23 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(2.18 +/- 0.15)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.77 s in the 8-1000 keV band
is 1.97 +/- 0.26 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: GRB151122A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18640
SUBJECT: GRB 151122A: Swift-XRT observations
DATE:    15/11/24 08:56:56 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), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), S.L. Gibson
(U. Leicester), J.P. Osborne (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 151122A (David Palmer et al. GCN Circ.
18637), collecting 3.0 ks of Photon Counting (PC) mode data between
T0+102.9 ks and T0+114.0 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):  299.6973  =  19:58:47.35
   Dec (J2000): -19.9063  =  -19:54:22.8
   Error: 4.7 arcsec (radius, 90% conf.)
   Count-rate: 0.0100 Â± 0.0023 ct s^-1
   Flux: (4.24 Â± 0.95)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
This source is 5.8" away from PMN J1958-1954, classified in SIMBAD as a 
radio source.

Source 2:
   RA (J2000):  299.6668  =  19:58:40.03
   Dec (J2000): -19.9360  =  -19:56:09.5
   Error: 4.9 arcsec (radius, 90% conf.)
   Count-rate: (3.9 Â± 1.6)e-3 ct s^-1
   Flux: (1.57 Â± 0.64)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
This source is 2.1" from HD 189004, a high proper-motion, K star.

Another uncatalogued was also detected, however this was too far from
the GRB position to be the afterglow.

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/00020560.

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


GRB_name: GRB151122A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18641
SUBJECT: GRB 151122A: Swift/UVOT Observations
DATE:    15/11/24 18:09:00 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and P. A. Evans (U.Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151122A
102884 s after the BAT trigger (Palmer et al., GCN Circ. 18637).
No optical afterglow consistent with either of the XRT positions
given by Evans et al. (GCN Circ 18640) is detected in the initial UVOT exposures.
For source 1, we do not detect any new source down to the detection limit.
For source 2, we only detect the bright high proper motion star HD 189004.

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

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

w2              102884       113997         2933         >21.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.20 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151118A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18642
SUBJECT: GRB 151118A iTelescope observation
DATE:    15/11/26 10:03:41 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU) 

We observed the field of GRB 151118A detected by Swift (trigger #664078; 
Amaral-Rogers et al., GCN Circ. 18611) with the iTelescope.Net (http://www.itelescope.net) 
T7 (17" Plane Wave) telescope located at the AstroCamp Observatory (Nerpio, Spain).  
20 images of 60 sec exposures were taken in the R filter starting from November 18 03:45:22 (UT) 
about 38.8 minutes after the trigger and stopped on November 18 04:23:04 (UT).  
We do not detect the optical afterglow both in the individual images and the stacked image 
at the enhanced X-ray afterglow position (Evans et al., GCN Circ. 18614).  The estimated 
five sigma upper limit of the combined image (total exposure of 1200 sec) is ~18.3 using 
the USNO-B1 catalog.


GRB_name: GRB151127A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18643
SUBJECT: GRB 151127A: Swift detection of a short burst
DATE:    15/11/27 09:24:29 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. D'Ai (INAF-IASFPA), P. A. Evans (U Leicester),
A. Maselli (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL) and T. Sakamoto (AGU) report on behalf of the
Swift Team:

At 09:08:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151127A (trigger=665268).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 19.778, -82.774 which is 
   RA(J2000) = 01h 19m 07s
   Dec(J2000) = -82d 46' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of about 0.5 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0.15 sec after the trigger. 

The XRT began observing the field at 09:10:09.0 UT, 79.2 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 19.4797, -82.7707 which
is equivalent to:
   RA(J2000)  = 01h 17m 55.13s
   Dec(J2000) = -82d 46' 14.5"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 135 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 1.02
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 77 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 0.12. 

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


GRB_name: GRB151127A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18644
SUBJECT: GRB 151127A: LCOGT-SSO optical upper limits
DATE:    15/11/27 12:51:46 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC/CAS), D. Malesani (DARK/NBI), Y. Qin (Geneva Observatory), 
Y.-H. Han (NAOC/CAS, HUST), and Y.-D. Hu (IAA-CSIC) report:

We observed the field of the short GRB 151127A (D'Ai et al., GCN 18643) 
with the 1-m LCOGT telescope at the Siding Spring Observatory. 
Observations started 27.42 UT on 2015-11-27 (i.e., 1.04 hr after the 
GRB), and we obtained 5x180s R-band and 8x180s I-band images.

No new source is detected inside or close to the XRT position (D'Ai et 
al., GCN 18643), down to 3-sigma upper limits of R > 20 mag and I > 19 
mag (calibrated against nearby USNO stars), at mean times of 1.17 and 
1.52 hr after the GRB, respectively.


GRB_name: GRB151127A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18645
SUBJECT: GRB 151127A: GROND K-band upper limit
DATE:    15/11/27 13:01:13 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

T. Schweyer and J. Greiner (both MPE Garching) report on behalf of
the GROND team:

We observed the field of GRB 151127A (Swift trigger 665268; D'Ai et
al., GCN #18643) simultaneously in JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at the ESO La
Silla Observatory (Chile).

Observations started at 09:12:30 UT on 2015-11-27, about 4 min after the 
GRB trigger. They were performed at an average seeing of 2" and at an 
average airmass of 2.3 during morning twilight, with the Sun at -6 deg. 
Due to the sky brightness, only the first two 1-min exposure K-band
images are useful.

We do not detect a source within the 2.6 arcsecond XRT error circle
(D'Ai et al., GCN #18643), down to a limiting magnitude of 
K(AB) > 16.5 mag. 


GRB_name: GRB151127A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18646
SUBJECT: GRB151127A: Planned XMM-Newton observation
DATE:    15/11/27 14:31:35 GMT
FROM:    Norbert Schartel at XMM-Newton/ESA  <too@xmm.esac.esa.int>

XMM-Newton will observe GRB GRB151127A at location
(RA=01h 17m 55.13s, DEC=-82d 46' 14.5", J2000),
starting at 13:35:45 UT, on November 28, 2015,
for an exposure of 17500 seconds.




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GRB_name: GRB151127A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18647
SUBJECT: GRB 151127A: Enhanced Swift-XRT position
DATE:    15/11/27 16:07:42 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 466 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 151127A, 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 = 19.47835, -82.77070 which is equivalent
to:

RA (J2000): 01h 17m 54.80s
Dec (J2000): -82d 46' 14.5"

with an uncertainty of 2.1 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: GRB151127A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18648
SUBJECT: GRB 151127A: Swift-BAT refined analysis
DATE:    15/11/27 16:48:26 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
A. D'Ai (INAF-IASFPA), 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-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 151127A (trigger #665268)
(D'Ai, et al., GCN Circ. 18643).  The BAT ground-calculated position is
RA, Dec = 19.664, -82.762 deg, which is 
   RA(J2000)  =  01h 18m 39.4s 
   Dec(J2000) = -82d 45' 42.1" 
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
 
The mask-weighted light curve shows a single spike starting at T_zero and
ending at ~T+0.25 sec.  T90 (15-350 keV) is 0.19 +- 0.04 sec
(estimated error including systematics).
 
The time-averaged spectrum from T+0.016 to T+0.220 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.26 +- 0.33.  The fluence in the 15-150 keV band is 2.3 +- 0.6 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.38 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/665268/BA/


GRB_name: GRB151127A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18649
SUBJECT: GRB 151127A: Swift-XRT refined Analysis
DATE:    15/11/27 17:09:09 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'ai (INAF-IASFPA), T.G.R.
Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), S.L. Gibson (U.
Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and
A. D'Ai report on behalf of the Swift-XRT team:

We have analysed 8.2 ks of XRT data for GRB 151127A (D'Ai et al. GCN
Circ. 18643), from 80 s to 18.4 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN Circ. 18647).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.15 (+0.17, -0.15).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+0.7, -0.5). The
best-fitting absorption column is  1.6 (+1.6, -0.6) x 10^21 cm^-2,
consistent with the Galactic value of 1.0 x 10^21 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 (4.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+1.6, -0.6) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.3 (+0.7, -0.5)

If the light curve continues to decay with a power-law decay index of
1.15, the count rate at T+24 hours will be 1.4 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x
10^-15 (6.4 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/00665268.

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


GRB_name: GRB151127A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18650
SUBJECT: GRB 151127A: Swift/UVOT Upper Limits
DATE:    15/11/27 18:22:40 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K Emery (UCL-MSSL) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151127A
77 s after the BAT trigger (D'Ai et al., GCN Circ. 18643).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 18647)
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            77          227          147         >20.8
white               77         1017          295         >21.2
w1                 668         6559          452         >20.3
m2                 816         6354          432         >20.0
w2                 594        18458         1696         >21.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.12 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151122A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18652
SUBJECT: GRB 151122A: Further Swift-XRT observations, no afterglow detected.
DATE:    15/11/28 13:58:35 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.

Swift-XRT has performed repeat observations of the field of GRB 151122A 
(Palmer et al., GCN Cric. 18637), collecting 4 ks of data from T0+373 ks 
to T0+442 ks.

Both of the X-ray sources reported by Melandri et al (GCN Circ. 18640) 
are still detected, with neither showing evidence of fading. We 
therefore conclude that these are unrelated to the GRB, and XRT did not 
detect the afterglow of GRB 151122A.

The 3-sigma upper limit from the initial observations (3 ks, from 
T0+102.9 ks and T0+114.0 ks) is 5e-3 ct/sec, which corresponds to a 
0.3-10 keV flux of approximately 2e-13 erg cm^-2 s^-1.

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


GRB_name: GRB151127A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18656
SUBJECT: GRB 151127A iTelescope observation
DATE:    15/12/02 13:35:18 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU) 

We observed the field of GRB 151127A detected by Swift (trigger #665268; 
D'Ai et al., GCN Circ. 18643) with the iTelescope.Net (http://www.itelescope.net) 
T30 (20" Plane Wave) telescope located at the Siding Spring Observatory (New South 
Wales, Australia).  20 images of 60 sec exposures were taken in the R filter 
starting from November 27 09:47:56 (UT) about 39.1 minutes after the trigger 
and stopped on November 27 10:23:18 (UT).  We do not detect the optical afterglow 
both in the individual images and the stacked image at the enhanced X-ray afterglow 
position (Goad et al., GCN Circ. 18647).  The estimated five sigma upper limit of 
the combined image (total exposure of 1200 sec) is ~18.2 using the USNO-B1 catalog.


GRB_name: GRB151205A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18657
SUBJECT: GRB 151205A: Swift detection of a burst
DATE:    15/12/05 16:01:30 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), P. D'Avanzo (INAF-OAB), C. Gronwall (PSU),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 15:46:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151205A (trigger=666352).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 229.282, +35.769, which is 
   RA(J2000)  =  15h 17m 08s
   Dec(J2000) = +35d 46' 09"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple overlapping peaks
with a total duration of about 25 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 15:47:32.7 UT, 91.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
229.2892, 35.7439 which is equivalent to:
   RA(J2000)  = 15h 17m 09.41s
   Dec(J2000) = +35d 44' 38.0"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 92 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 (1.58 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.7
(+3.55/-2.93) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.31e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 100 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. 

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: GRB151205A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18658
SUBJECT: GRB 151205A: Enhanced Swift-XRT position
DATE:    15/12/05 20:26:56 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 2174 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 151205A, 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 = 229.28861, +35.74392 which is equivalent
to:

RA (J2000): 15h 17m 9.27s
Dec (J2000): +35d 44' 38.1"

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

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

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


GRB_name: GRB151205B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18659
SUBJECT: GRB 151205B: Swift detection of a burst
DATE:    15/12/05 21:51:08 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), P. D'Avanzo (INAF-OAB), C. Gronwall (PSU),
L. M. Z. Hagen (PSU), H. A. Krimm (CRESST/GSFC/USRA),
A. Melandri (INAF-OAB), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 21:43:14 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151205B (trigger=666378).  Swift could not slew immediately
to the burst due to an observing contraint. 
The BAT on-board calculated location is 
RA, Dec 41.158, -43.481 which is 
   RA(J2000) = 02h 44m 38s
   Dec(J2000) = -43d 28' 49"
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 5 sec.  The peak count rate
was ~1800 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+50.6
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is F. E. Marshall (marshall 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: GRB151205A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18660
SUBJECT: GRB 151205A: Swift/UVOT Upper Limits
DATE:    15/12/05 23:00:57 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) 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 151205A
101 s after the BAT trigger (Cummings et al., GCN Circ. 18657). No
optical afterglow consistent with the XRT position (Osborne et al.
GCN Circ. 18658) 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              101         5796          383         >21.15
v                  590         6207          236         >19.25
b                  514         5591          236         >20.14
u                  259         6713          552         >20.21
w1                 639         6617          413         >20.10
m2                4776         6412          393         >20.07
w2                 565         6002          236         >19.95

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: GRB151205B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18661
SUBJECT: GRB 151205B: Swift-XRT observations
DATE:    15/12/05 23:07:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB),
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and D.N. Burrows
(PSU) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 151205B at 22:35:21.5 UT,
3127.1 seconds after the BAT trigger. No source was detected in 245 s
of promptly downlinked data. We are waiting for the full dataset to
detect and localise the XRT counterpart.


GRB_name: GRB151205B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18662
SUBJECT: GRB151205B: Initial UVOT observations
DATE:    15/12/05 23:09:33 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

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

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 3131 seconds after the BAT trigger (Marshall et al., GCN Circ.
18659). No credible afterglow candidate has been found in the initial
data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle.
The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region
for the list of sources generated on-board covers 100% of the BAT 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.

[GCN OPS NOTE(20jan16): Per author's request, the burst name in the
Subject-line was changed from "A" to "B".]


GRB_name: GRB151205A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18663
SUBJECT: GRB 151205A: Garching Telescope Upper Limit
DATE:    15/12/05 23:49:31 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

T. Schweyer (MPE Garching) and D. A. Kann (TLS Tautenburg) report on
behalf of the GROND team:

We observed the field of GRB 151205A (Swift trigger 666352; J. R. Cummings
et al., GCN #18657) with the Garching 0.6m telescope.

Observations started at 16:24:57 UT on 2015-12-05, about 39 min after the
GRB trigger. They were performed at an average airmass of 3.4 during
evening twilight.

We obtained 6 images of 180s exposure time in R (for a total exposure time
of 18 min) with the midtime at 16:35:18 UT (MJD=57361.691180). We do not
detect a source within the 1".8 enhanced XRT error circle (J. P. Osborne
et al., GCN #18658), down to a limiting magnitude of R(AB) > 19.4 mag. The
R band is calibrated against SDSS DR8.


GRB_name: GRB151205A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18664
SUBJECT: GRB 151205A: Fermi GBM detection
DATE:    15/12/06 00:08:29 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

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

"At 15:46:01.90 UT on 05 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151205A (trigger 471023165 / 151205657)
which was also detected by the Swift/BAT (Cummings et al. 2015, GCN 18657).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 76 degrees.

The GBM light curve consists of several episodes
with a duration (T90) of about 56 s (50-300 keV).
The time-averaged spectrum from T0-2.05 s to T0+55.30 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is 1.06 +/- 0.48 and
the cutoff energy, parameterized as Epeak, is 153 +/- 12 keV

The event fluence (10-1000 keV) in this time interval is
(2.56 +/- 0.21)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.34 s in the 10-1000 keV band
is 1.36 +/- 0.15 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: GRB151205B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18665
SUBJECT: GRB 151205B: MASTER-NET early  optical observations 
DATE:    15/12/06 00:26:57 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy,   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.Senik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
21:43:14.53

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)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  GRB151205B (Marshall et. al. GCN 
18659) 28 sec after notice time and 63 sec after trigger time at 21:44:18 
UT in two polarisations. On our first (10s exposure)  set we haven't found 
optical transient  within SWIFT error-box (ra=02 44 38 dec=-43 28 50 
r=0.050000).
The 5-sigma upper limit has been about 17.0 mag.

We obtain a following early upper limits at a single an coadd images

T_start  T-Ts  T-Tm  Expt. Mlimit  Coadd
--------|----|-----|-----|-------|-------|
21:44:18   63    68    10    17.0   1
21:44:18   63   115    60    18.7   3
21:44:18   63   501   680    20.6  10
21:44:51   96   106    20    17.8   1
21:45:32  137   152    30    18.1   1
21:46:21  187   207    40    18.3   1
21:47:21  246   271    50    18.7   1
21:48:31  316   346    60    19.0   1
21:49:51  396   436    80    19.3   1
21:51:47  513   563   100    19.6   1
21:53:45  630   695   130    19.9   1
21:56:13  778   858   160    20.0   1
...

Ts - is exposure start time
Tm - is exposure middle time
T  - is trigger time

The message may be cited.


GRB_name: GRB151205C
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18666
SUBJECT: GRB 151205C: MAXI/GSC detection
DATE:    15/12/06 01:51:18 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

GRB 151205C: MAXI/GSC detection

M. Nakajima, H. Negoro (Nihon U.), M. Serino (RIKEN), T. Sakamoto (AGU),
S. Nakahira, 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, M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech),
A. Yoshida, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.),
Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (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 UT 2015/12/05 23:54:06.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (329.725 deg, 77.705 deg) = (21 58 54, +77 42 17) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.24 deg and 0.2 deg, respectively.
The roll angle of long axis from the north direction is 102.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 152 +- 24 mCrab
(4-10keV, 1 sigma error).

Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(326.621 deg, 76.996 deg) = (21 46 29, +76 59 46) (J2000)
(328.465 deg, 76.767 deg) = (21 53 51, +76 46 02) (J2000)
(333.174 deg, 78.383 deg) = (22 12 41, +78 23 00) (J2000)
(331.143 deg, 78.636 deg) = (22 04 34, +78 38 08) (J2000)

There was no significant excess flux in the previous transit at UT 22:21
and in the next transit at 12/6 01:26 UT with an upper limit of 20 mCrab for each.

Detection Information:
http://maxi.riken.jp/alert/novae/7361767105/7361767105.htm


GRB_name: GRB151205C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18667
SUBJECT: GRB 151205C: Tiled Swift observations
DATE:    15/12/06 03:09:15 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 151205C. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00049

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: GRB151205A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18668
SUBJECT: GRB 151205A, Swift-BAT refined analysis
DATE:    15/12/06 05:09:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), 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-315 to T+934 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 151205A (trigger #666352)
(Cummings, et al., GCN Circ. 18657).  The BAT ground-calculated position is
RA, Dec = 229.291, 35.767 deg, which is
   RA(J2000)  =  15h 17m 09.7s 
   Dec(J2000) = +35d 46' 01.7" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 93%.
 
The mask-weighted light curve shows several overlapping peaks starting at
~T-10 sec, peaking at ~T+3 sec, with a long tail out to T+170 sec.
T90 (15-350 keV) is 62.8 +- 12.3 sec (estimated error including systematics).
 
The time-averaged spectrum from T-4.0 to T+69.5 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.17 +- 0.13.  The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.98 sec in the 15-150 keV band
is 0.6 +- 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/666352/BA/


GRB_name: GRB151205A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18669
SUBJECT: GRB 151205A: Swift-XRT refined Analysis
DATE:    15/12/06 16:01:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers
(PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A.
Evans (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB) and J.R. Cummings report on behalf
of the Swift-XRT team:

We have analysed 7.1 ks of XRT data for GRB 151205A (Cummings et al.
GCN Circ. 18657), from 81 s to 18.6 ks after the  BAT trigger. The data
comprise 133 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 Osborne et
al. (GCN Circ. 18658).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.3 (+/-0.4), followed by a break at T+131 s to an alpha
of 1.73 (+0.07, -0.06).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.23 (+0.14, -0.13). The
best-fitting absorption column is  5.6 (+1.5, -1.3) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.90 (+0.31, -0.29)
and a best-fitting absorption column of 7.4 (+2.5, -2.1) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.7 x 10^-11 (7.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.4 (+2.5, -2.1) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 5.6 sigma
Photon index:      1.90 (+0.31, -0.29)

If the light curve continues to decay with a power-law decay index of
1.73, the count rate at T+24 hours will be 2.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.9 x
10^-15 (1.6 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/00666352.

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


GRB_name: GRB151205B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18670
SUBJECT: GRB 151205B, Swift-BAT refined analysis
DATE:    15/12/06 17:03:30 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC),H. A. Krimm (GSFC/USRA),A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), F. E. Marshall (NASA/GSFC),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 15120B (trigger #666378)
(Marshall, et al., GCN Circ. 18659).  The BAT ground-calculated position is
RA, Dec = 41.190, -43.461 deg which is
    RA(J2000)  =  02h 44m 45.6s
    Dec(J2000) = -43d 27' 39.8"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.

The mask-weighted light curve shows a single peak starting at T-2 sec
with total duration of ~5 seconds. The spacecraft slewed away from the
burst location at about T+350 seconds. T90 (15-350 keV) is 1.4 +- 0.2 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.2 to T+1.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.74 +- 0.33.  The fluence in the 15-150 keV band is 7.7 +- 1.6 x 10^-8erg/cm2.
The 1-sec peak photon flux measured from T+0.25 sec in the 15-150 keV band
is 0.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/666378/BA/


GRB_name: GRB151205C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18671
SUBJECT: GRB 151205C: Swift-XRT observations
DATE:    15/12/06 22:48:06 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

A. Melandri, P. D'Avanzo (INAF-OAB) A. D'Ai (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 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 151205C (Nakajima et al. GCN Circ. 18666) in a series of
observations tiled on the sky. The total exposure time is 2.5 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 790 s. The data were collected between T0+11.1 ks and T0+22.8 ks,
and are entirely in Photon Counting (PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.02 to ~0.03 ct s^-1, corresponding to a 0.3-10 keV observed flux of
7.6e-13 to 1.1e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

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_GRB00049.

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


GRB_name: GRB151205B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18672
SUBJECT: GRB 151205B: further Swift-XRT observations
DATE:    15/12/06 23:59:28 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, A. Melandri (INAF-OAB), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA), L.M. McCauley (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. Maselli  (INAF-IASFPA), F. E. Marshall
(NASA/GSFC) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

We have analysed 3.3 ks of Photon Counting (PC) mode XRT data for the
Swift/BAT-detected burst GRB 151205B (Marshall et al. GCN Circ. 18659),
collected between T0+3.1 ks and T0+68.9 ks. 

The first set of observations consists of 1.0 ks of data collected 
between T0+3.1 ks and T0+5.7 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 is 7.7e-3 ct  s^-1,
corresponding to a 0.3-10 keV observed flux of 2.7e-13 erg cm^-2 s^-1
(assuming a typical GRB spectrum).

The second set of observations consists of 2.3 ks data collected 
between T0+39.8 ks and T0+68.9 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 is 3.7e-3 ct  s^-1,
corresponding to a 0.3-10 keV observed flux of 1.3e-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/00666378.

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


GRB_name: GRB130831A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18673
SUBJECT: GRB 130831A: MASTER early OT detection and LC
DATE:    15/12/07 14:17:09 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

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

After this observation night there was no electricity at the
Tunka observatory for a few days . Therefore, the data were not immediately available. We
forgot to check  the follow-up after power is restored and rediscovered
this source as optical transient  during the data reprocessing of the
present time.

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Tunka was pointed to the  GRB130831A 58 sec after trigger
time at 2013-08-31 13:05:14 UT. On our second (20s exposure 120 sec after
trigger)  set we
found 1 optical transient within SWIFT error-box (ra=23 54 36 dec=+29 27
00 r=0.05) brighter then 15.1.


  T-Tmid      Date      Time       Expt.      Ra                Dec           Mag   
-------|-----------|----------|-------|-----------------|-----------------|-------  
   130   2013-08-31  13:06:16      20    23h 54m 29.82s   +29d 25m 47.1s     14.34  

The 5-sigma upper limit has been about 15.1mag

The automatic reduction data are below:

date          time                  coord2000          Exp.  Polaroid    mag     err
                UT                                       s
2013-08-31 13:05:13           -               -         10 P/     >15.4
2013-08-31 13:05:14           -               -         10 P\     >15.5
2013-08-31 13:06:14.969 23h 54m 29.77s  +29d 25m 46s.5  20 P/ 14.19   0.13
2013-08-31 13:06:16.09  23h 54m 29.82s  +29d 25m 47s.1  20 P\ 14.34   0.15
2013-08-31 13:07:37.707 23h 54m 29.94s  +29d 25m 46s.6  40 P 13.70   0.07
2013-08-31 13:07:38.411 23h 54m 29.89s , +29d 25m 46s.3 40 P 14.08   0.08
2013-08-31 13:09:21.157 23h 54m 29.87s , +29d 25m 46s.5 60 P 13.96   0.06
2013-08-31 13:09:22.329 23h 54m 29.86s , +29d 25m 46s.3 60 P 14.17   0.06
2013-08-31 13:11:11.731 23h 54m 29.87s , +29d 25m 46s.8 80 P 13.96   0.05
2013-08-31 13:11:12.656 23h 54m 29.87s , +29d 25m 46s.4 80 P 14.05   0.04
2013-08-31 13:13:26.831 23h 54m 29.87s , +29d 25m 46s.4 110     P 13.14   0.02
2013-08-31 13:13:26.904 23h 54m 29.87s , +29d 25m 46s.7 110     P 13.23   0.01
2013-08-31 13:16:22.741 23h 54m 29.88s , +29d 25m 46s.4 140     P 12.76   0.01
2013-08-31 13:16:23.769 23h 54m 29.89s , +29d 25m 46s.7 140     P 12.79   0.01
2013-08-31 13:19:48.725 23h 54m 29.88s , +29d 25m 46s.5 180     P 13.10   0.01
2013-08-31 13:19:49.319 23h 54m 29.89s , +29d 25m 46s.6 180     P 13.03   0.01
2013-08-31 13:23:42.166 23h 54m 29.89s , +29d 25m 46s.6 180     P 13.44   0.01
2013-08-31 13:23:43.007 23h 54m 29.89s , +29d 25m 46s.6 180     P 13.40   0.01
2013-08-31 13:27:40.436 23h 54m 29.90s , +29d 25m 46s.5 180     P 13.80   0.01
2013-08-31 13:27:41.309 23h 54m 29.89s , +29d 25m 46s.7 180     P 13.79   0.01
2013-08-31 13:31:39.264 23h 54m 29.88s , +29d 25m 46s.7 180     P 14.08   0.02
2013-08-31 13:31:39.957 23h 54m 29.88s , +29d 25m 46s.8 180     P 14.12   0.01
2013-08-31 13:36:03.651 23h 54m 29.89s , +29d 25m 46s.4 180     P 14.44   0.02
2013-08-31 13:36:04.486 23h 54m 29.89s , +29d 25m 46s.5 180     P 14.51   0.02
2013-08-31 13:39:59.065 23h 54m 29.88s , +29d 25m 46s.6 180     P 14.55   0.02
2013-08-31 13:39:59.918 23h 54m 29.89s , +29d 25m 46s.7 180     P 14.53   0.02
2013-08-31 13:44:00.574 23h 54m 29.89s , +29d 25m 46s.7 180     P 14.72   0.02
2013-08-31 13:44:01.425 23h 54m 29.89s , +29d 25m 46s.6 180     P 14.78   0.03
2013-08-31 13:48:10.668 23h 54m 29.91s , +29d 25m 46s.5 180     P 14.94   0.03
2013-08-31 13:48:11.488 23h 54m 29.87s , +29d 25m 46s.5 180     P 14.95   0.02
2013-08-31 13:52:19.736 23h 54m 29.89s , +29d 25m 46s.3 180     P 14.97   0.03
2013-08-31 13:52:20.267 23h 54m 29.88s , +29d 25m 46s.3 180     P 14.99   0.03
2013-08-31 13:56:25.283 23h 54m 29.89s , +29d 25m 46s.7 180     P 15.11   0.03
2013-08-31 13:56:25.394 23h 54m 29.88s , +29d 25m 46s.6 180     P 15.05   0.03
2013-08-31 14:00:30.776 23h 54m 29.88s , +29d 25m 46s.7 180     P 15.16   0.03
2013-08-31 14:00:31.465 23h 54m 29.88s , +29d 25m 46s.6 180     P 15.13   0.03
2013-08-31 14:04:35.057 23h 54m 29.88s , +29d 25m 46s.5 180     P 15.18   0.03
2013-08-31 14:04:37.274 23h 54m 29.90s , +29d 25m 46s.8 180     P 15.10   0.03
2013-08-31 14:08:42.051 23h 54m 29.88s , +29d 25m 46s.6 180     P 15.18   0.03
2013-08-31 14:08:42.358 23h 54m 29.89s , +29d 25m 46s.8 180     P 15.18   0.03
2013-08-31 14:13:16.808 23h 54m 29.88s , +29d 25m 46s.5 180     P 15.16   0.03
2013-08-31 14:13:17.534 23h 54m 29.87s , +29d 25m 46s.6 180     P 15.19   0.03
2013-08-31 14:17:26.33  23h 54m 29.88s , +29d 25m 46s.6 180     P 15.22   0.03
2013-08-31 14:17:26.78  23h 54m 29.89s , +29d 25m 46s.7 180     P 15.16   0.03
2013-08-31 14:21:33.6   23h 54m 29.87s , +29d 25m 46s.4 180     P 15.33   0.03
2013-08-31 14:21:34.446 23h 54m 29.89s , +29d 25m 46s.6 180     P 15.27   0.03
2013-08-31 14:26:01.003 23h 54m 29.90s , +29d 25m 46s.7 180     P 15.37   0.03
2013-08-31 14:26:01.882 23h 54m 29.89s , +29d 25m 46s.5 180     P 15.30   0.03
2013-08-31 14:29:49.129 23h 54m 29.89s , +29d 25m 46s.7 180     P 15.45   0.03
2013-08-31 14:29:50.359 23h 54m 29.87s , +29d 25m 46s.7 180     P 15.39   0.03
2013-08-31 14:33:42.843 23h 54m 29.90s , +29d 25m 46s.4 180     P 15.47   0.03
2013-08-31 14:33:43.028 23h 54m 29.89s , +29d 25m 47s.0 180     P 15.46   0.04
2013-08-31 14:37:43.134 23h 54m 29.87s , +29d 25m 46s.4 180     P 15.52   0.04
2013-08-31 14:37:44.1   23h 54m 29.87s , +29d 25m 46s.6 180     P 15.42   0.04
2013-08-31 14:41:37.936 23h 54m 29.90s , +29d 25m 46s.5 180     P 15.66   0.04
2013-08-31 14:41:40.554 23h 54m 29.90s , +29d 25m 46s.5 180     P 15.57   0.04
2013-08-31 14:45:27.386 23h 54m 29.89s , +29d 25m 46s.4 180     P 15.71   0.04
2013-08-31 14:45:28.83  23h 54m 29.92s , +29d 25m 46s.7 180     P 15.54   0.04
2013-08-31 14:49:23.464 23h 54m 29.88s , +29d 25m 46s.6 180     P 15.70   0.04
2013-08-31 14:49:24.934 23h 54m 29.89s , +29d 25m 46s.6 180     P 15.58   0.04
2013-08-31 14:53:18.194 23h 54m 29.88s , +29d 25m 46s.4 180     P 15.66   0.04
2013-08-31 14:53:18.686 23h 54m 29.90s , +29d 25m 46s.8 180     P 15.58   0.04
2013-08-31 14:57:36.995 23h 54m 29.87s , +29d 25m 46s.3 180     P 15.76   0.04
2013-08-31 14:57:37.418 23h 54m 29.90s , +29d 25m 46s.6 180     P 15.63   0.04
2013-08-31 15:01:42.896 23h 54m 29.91s , +29d 25m 46s.3 180     P 15.88   0.05
2013-08-31 15:01:43.521 23h 54m 29.92s , +29d 25m 46s.6 180     P 15.69   0.04
2013-08-31 15:05:42.207 23h 54m 29.88s , +29d 25m 46s.6 180     P 15.95   0.04
2013-08-31 15:05:43.764 23h 54m 29.89s , +29d 25m 46s.7 180     P 15.75   0.04
2013-08-31 15:09:53.777 23h 54m 29.89s , +29d 25m 46s.4 180     P 15.93   0.05
2013-08-31 15:09:54.9   23h 54m 29.90s , +29d 25m 46s.5 180     P 15.84   0.05
2013-08-31 15:14:14.225 23h 54m 29.90s , +29d 25m 46s.5 180     P 16.04   0.05
2013-08-31 15:14:14.636 23h 54m 29.88s , +29d 25m 46s.5 180     P 15.90   0.05
2013-08-31 15:18:32.515 23h 54m 29.88s , +29d 25m 46s.4 180     P 15.98   0.05
2013-08-31 15:18:32.972 23h 54m 29.62s , +29d 25m 46s.7 180     P 16.80   0.08
2013-08-31 15:22:42.728 23h 54m 29.86s , +29d 25m 46s.4 180     P 16.13   0.05
2013-08-31 15:22:43.005 23h 54m 29.72s , +29d 25m 47s.5 180     P 16.50   0.08
2013-08-31 15:27:06.639 23h 54m 29.88s , +29d 25m 46s.1 180     P 16.23   0.06
2013-08-31 15:27:07.166 23h 54m 29.90s , +29d 25m 46s.6 180     P 15.99   0.06
2013-08-31 15:31:14.164 23h 54m 29.89s , +29d 25m 46s.5 180     P 16.32   0.06
2013-08-31 15:31:14.663 23h 54m 29.89s , +29d 25m 47s.1 180     P 16.06   0.06
2013-08-31 15:35:08.964 23h 54m 29.87s , +29d 25m 46s.4 180     P 16.39   0.07
2013-08-31 15:35:10.803 23h 54m 29.97s , +29d 25m 49s.0 180     P 16.83   0.10
2013-08-31 15:39:37.457 23h 54m 29.89s , +29d 25m 46s.7 180     P 16.47   0.07
2013-08-31 15:39:38.229 23h 54m 29.84s , +29d 25m 48s.1 180     P 16.73   0.10
2013-08-31 15:43:50.963 23h 54m 29.89s , +29d 25m 46s.6 180     P 16.51   0.07
2013-08-31 15:43:51.628 23h 54m 29.68s , +29d 25m 46s.2 180     P 17.30   0.14
2013-08-31 15:47:41.439 23h 54m 29.92s , +29d 25m 46s.8 180     P 16.41   0.08
2013-08-31 15:47:41.868 23h 54m 29.70s , +29d 25m 46s.3 180     P 16.70   0.10
2013-08-31 15:51:28.744 23h 54m 29.89s , +29d 25m 46s.7 180     P 16.57   0.08
2013-08-31 15:51:29.974 23h 54m 29.69s , +29d 25m 45s.8 180     P 16.99   0.12
2013-08-31 15:55:28.935 23h 54m 29.91s , +29d 25m 46s.6 180     P 16.68   0.11
2013-08-31 15:55:29.91  23h 54m 29.92s , +29d 25m 46s.6 180     P 16.36   0.10
2013-08-31 15:59:32.081 23h 54m 29.88s , +29d 25m 46s.5 180     P 16.78   0.09
2013-08-31 15:59:32.882 23h 54m 29.77s , +29d 25m 45s.2 180     P 16.75   0.10
2013-08-31 16:03:45.019 23h 54m 29.89s , +29d 25m 46s.2 180     P 16.71   0.09
2013-08-31 16:03:45.878 23h 54m 29.73s , +29d 25m 49s.2 180     P 16.98   0.13
2013-08-31 16:03:45.878 23h 54m 29.67s , +29d 25m 45s.0 180     P 17.21   0.14
2013-08-31 16:07:40.752 23h 54m 29.87s , +29d 25m 46s.7 180     P 16.68   0.10
2013-08-31 16:07:40.756 23h 54m 29.85s , +29d 25m 46s.9 180     P 16.53   0.11
2013-08-31 16:11:45.003 23h 54m 29.89s , +29d 25m 46s.5 180     P 16.65   0.09
2013-08-31 16:11:46.074 23h 54m 29.68s , +29d 25m 47s.0 180     P 16.51   0.11
2013-08-31 16:16:04.472 23h 54m 29.89s , +29d 25m 46s.2 180     P 16.90   0.11
2013-08-31 16:16:05.21  23h 54m 29.71s , +29d 25m 46s.2 180     P 17.15   0.14
2013-08-31 16:20:16.552 23h 54m 29.88s , +29d 25m 46s.4 180     P 16.71   0.09
2013-08-31 16:20:16.892 23h 54m 29.90s , +29d 25m 47s.3 180     P 16.63   0.12
2013-08-31 16:24:28.011 23h 54m 29.92s , +29d 25m 46s.2 180     P 16.74   0.12
2013-08-31 16:24:28.419 23h 54m 29.64s , +29d 25m 46s.9 180     P 17.97   0.22
2013-08-31 16:28:38.273 23h 54m 29.91s , +29d 25m 46s.3 180     P 16.75   0.11
2013-08-31 16:28:39.181 23h 54m 29.66s , +29d 25m 47s.7 180     P 17.10   0.16
2013-08-31 16:32:35.03  23h 54m 29.88s , +29d 25m 46s.4 180     P 17.03   0.12
2013-08-31 16:36:41.311 23h 54m 29.91s , +29d 25m 46s.9 180     P 16.88   0.13
2013-08-31 16:36:41.982 23h 54m 29.90s , +29d 25m 45s.2 180     P 16.91   0.14
2013-08-31 16:40:40.333 23h 54m 29.85s , +29d 25m 46s.5 180     P 17.07   0.15
2013-08-31 16:40:40.788 23h 54m 29.80s , +29d 25m 46s.5 180     P 18.57   0.32


The automatic  light curve is available at
http://observ.pereplet.ru/images/GRB130831A.jpg

The message may be cited.


GRB_name: GRB151205B
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18674
SUBJECT: GRB 151205B: Deep GROND Upper limits
DATE:    15/12/08 22:02:39 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

R. Yates (MPE Garching) , 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 151205B (Swift trigger 666378; Marshall et
al., GCN #18659) 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 01:21 UT on 06/12/2015, 3hrs 38 mins after the GRB
trigger, and continued for several hours. We obtained a second epoch in
the following night.

We stacked the four deepest images of the first night (exposure times 7920
s in g'r'i'z' and 6600 s in JHK). They were performed at an average seeing
of 0".77 and an average airmass of 1.04. The observations of the second
night (exposure times 5760 s in g'r'i'z' and 5400 s in JHK) were obtained
at 0".62 seeing and airmass 1.04.

As there is no XRT detection for this GRB (Kennea et al., GCN #18661;
D'Avanzo et al., GCN #18672), we performed image subtraction. We note that
the g'r'i'z' images do not cover about 25% of the revised BAT error circle
(Ukwatta et al., GCN #18670) to the north and east. The JHK images cover
both the flight and the revised BAT error circle completely.

No significantly variable sources are detected in any band. The formal
upper limits (all in AB system) of our images, centered at 0.1939 days
after the GRB, are:

g' > 26.5 mag,
r' > 26.5 mag,
i' > 25.6 mag,
z' > 25.0 mag,
J > 22.7 mag,
H > 22.2 mag, and
K > 21.3 mag.

The given limits are derived based on calibrating the images against GROND
zero points and 2MASS field stars and are not corrected for the Galactic
foreground extinction corresponding to a reddening of E_(B-V)= 0.02 in the
direction of the burst (Schlegel et al. 1998).


GRB_name: GRB151205A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18676
SUBJECT: GRB 151205A: Khureltogot upper limit
DATE:    15/12/09 10:19:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova (IKI), S. Schmalz (AIP), E. Mazaeva (IKI),  N. Tungalag 
(Research Center of Astronomy and Geophysics MAS),   I. Molotov (KIAM), 
  A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of Swift GRB 151205A (Cummings et al., GCN 18657)
with ORI-40 telescope of Khureltogot observatory starting on  Dec., 5 
(UT) 20:49:25, i.e. ~6 hours after the burst trigger.  We do not detect 
any object within enhanced XRT error circle  (Osborne et al., GCN 18658).
Photometry of the field is following


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

2015-12-05 20:49:25 0.24451 none  90*60 21.3

Photometry is based on nearby SDSS stars,
R magnitude deduced from Lupton's transformations.

SDSS id              R(Lupton)
J151723.45+354524.6  13.849 0.011
J151723.30+354351.0  14.562 0.012
J151718.79+354350.3  15.801 0.013


GRB_name: GRB151205C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18677
SUBJECT: GRB 151205C: Optical follow-up observations at Kiso
DATE:    15/12/10 03:00:06 GMT
FROM:    Masaomi Tanaka at NAOJ  <masaomi.tanaka@nao.ac.jp>

Yuki Kikuchi (U. of Tokyo), Masaomi Tanaka (NAOJ), Ryou Ohsawa,
Makoto Ichiki, Shigeyuki Sako, Tomoki Morokuma, Mamoru Doi (U. of Tokyo),
Nozomu Tominaga (Konan U.), Motoko Serino (RIKEN), Akihiro Suzuki,
Keiichi Maeda (Kyoto U.), and Takanori Sakamoto (AGU) report:

We performed optical non-filter imaging observations for
the MAXI-detected burst GRB 151205C (Nakajima et al. GCN Circ. 18666)
with a prototype model camera of Tomo-e Gozen (Tomo-e PM).
Tomo-e Gozen is a wide-field optical imaging camera
with 84 1kx2k CMOS sensors on the focal plane of
the 1.05-m Kiso Schmidt telescope (Sako et al. in preparation,
http://www.ioa.s.u-tokyo.ac.jp/tomoe/).
The prototype model camera has 8 CMOS sensors along the RA direction
with spatial gaps of 25 arcmin between the adjacent chips.
The field-of-view of each chip is 39.7 arcmin (RA) x 22.4 arcmin (Dec).
Thanks to the low dark current of the sensors in room
temperature, we operate the CMOS sensors without coolers
which enables us to make a light-weight camera system.
By using 1 of 8 chips of Tomo-e PM,
multiple regions which cover in total 95% of the localization area 
(with the following central coordinates) have been observed.

 RA       | Dec       | Obs. time        | t-t0*  | Exptime |
 (J2000)  | (J2000)   | (UT)             | (days) | (sec)   |
 22:00:34 | +77:39:51 | 2015 Dec 6 14:08 | 0.59   | 150     |
 21:58:01 | +77:41:46 | 2015 Dec 6 14:25 | 0.60   | 150     |
 22:05:23 | +78:26:45 | 2015 Dec 7 09:12 | 1.39   | 180     |
 22:02:51 | +78:06:14 | 2015 Dec 7 09:15 | 1.39   | 180     |
 21:55:36 | +77:28:11 | 2015 Dec 7 09:22 | 1.39   | 180     |
 21:58:37 | +77:45:37 | 2015 Dec 7 09:26 | 1.40   | 180     |
 22:08:11 | +78:19:44 | 2015 Dec 8 14:22 | 2.60   | 150     |
 22:04:56 | +78:03:18 | 2015 Dec 8 14:25 | 2.61   | 144     |
 22:02:25 | +77:42:13 | 2015 Dec 8 14:29 | 2.61   | 144     |
 21:58:14 | +77:22:13 | 2015 Dec 8 14:31 | 2.61   | 180     |
 21:55:13 | +77:04:13 | 2015 Dec 8 14:34 | 2.61   | 180     |
* time after the burst

We performed image subtraction using
PTF R-band data taken on 2011 Jul 17 as references
(obtained through IPAC, Law et al. 2009, PASP, 121, 1395;
Laher et al. 2014, PASP, 126, 674).
No new transient objects have been found within these fields.
The limiting magnitudes of our data are about 20 mag
(calibrated with USNO UCAC3 catalog, Zacharias et al. 2010, AJ, 139, 2184).


GRB_name: GRB151210A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18678
SUBJECT: GRB 151210A: Swift detection of a burst
DATE:    15/12/10 03:35:37 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

P. A. Evans (U Leicester), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 03:12:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151210A (trigger=666931).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 65.182, -71.230 which is 
   RA(J2000)  =  04h 20m 44s
   Dec(J2000) = -71d 13' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple of peaks
with a duration of about 60 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~14 sec after the trigger. 

The XRT began observing the field at 03:15:26.7 UT, 150.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 65.1177,
-71.2509 which is equivalent to:
   RA(J2000)  = 04h 20m 28.25s
   Dec(J2000) = -71d 15' 03.4"
with an uncertainty of 2.1 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 consistent with the Galactic value of 1.30
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 150 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 0.12. 

Burst Advocate for this burst is P. A. Evans (pae9 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: GRB151210A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18679
SUBJECT: GRB 151210A: Optical afterglow candidate from LCOGT-Cerro Tololo
DATE:    15/12/10 05:33:13 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Yanhui Han (NAOC/CAS, HUST), Thomas Kruehler (ESO), Dong Xu (NAOC/CAS), 
Youdong Hu (IAA-CSIC), and Yin Qing (Geneva Observatory) report:

We observed the field of GRB 151210A (Evans et al., GCN 18678) with the 
1-m LCOGT telescope at Cerro Tololo, Chile. Observations started 
03:34:06 UT on 2015-12-10 (i.e., 21.2 mins after the GRB), and we 
obtained 10x240s R-band images.

Within the XRT error circle (Evans et al., GCN 18678), an uncatalogued 
optical source is detected in our stacked image at coordinates:

R. A. = 04:20:28.048
Dec. = -71:15:02.53

with an error radius of ~0.5 arcsec. The object roughly has R~21.5 mag, 
calibrated with the nearby USNO B1 field. We thus consider that the 
source is very likely the optical afterglow of GRB 151220A.


GRB_name: GRB151210A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18680
SUBJECT: GRB 151210A: GROND Afterglow Confirmation
DATE:    15/12/10 05:39:43 GMT
FROM:    Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>

P. Wiseman, T. Kruehler (both MPE Garching), 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 151210A (Swift trigger 666931; Evans et
al., GCN #18678) 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 03:17:35 UT on 10/12/2015, 279 sec after the
GRB trigger, and are ongoing.

We detect a source not seen in the DSS at the edge of the refined XRT
error circle (Evans et al., GCN #18678) at:

RA (J2000) = 04:20:27.91
Dec. (J2000) = -71:15:02.6

with an error of 0".5 in each coordinate. We suggest that this is the
afterglow of the GRB, as we also detect fading between observations. This
source is also seen by LCOGT (Han et al., GCN #18679).

Based on observations with an integration time of 594 sec (griz) and
540 sec (JHK) centered 54 min after the GRB trigger, we derive
magnitudes

g' = 23.9 +/- 0.2  mag,
r' = 22.1 +/- 0.1 mag,
i' = 21.7 +/- 0.1 mag,
z' = 21.2 +/- 0.1 mag,
J = 20.3 +/- 0.2 mag, and
H = 19.8 +/- 0.2 mag.

The given limits are derived based on calibrating the images against
GROND zero points and 2MASS field stars and are not corrected for the
Galactic foreground extinction corresponding to a reddening of E_(B-
V)= 0.11 in the direction of the burst (Schlafly & Finkbeiner 2011).


GRB_name: GRB151210A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18681
SUBJECT: GRB 151210A: Enhanced Swift-XRT position
DATE:    15/12/10 07:47:44 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 1491 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151210A, 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 = 65.11644, -71.25075 which is equivalent
to:

RA (J2000): 04h 20m 27.95s
Dec (J2000): -71d 15' 02.7"

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: GRB151210A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18682
SUBJECT: GRB 151210A: Swift-XRT refined Analysis
DATE:    15/12/10 13:01:19 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), T.G.R. Roegiers (PSU), A.P. Beardmore (U.
Leicester), S.L. Gibson (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), L.M. McCauley (PSU) and P.A.
Evans report on behalf of the Swift-XRT team:

We have analysed 7.1 ks of XRT data for GRB 151210A (Evans et al. GCN
Circ. 18678), from 137 s to 23.7 ks after the  BAT trigger. The data
comprise 145 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. 18681).

The light curve can be modelled with an initial power-law decay with an
index of alpha=5.1 (+0.9, -0.8), followed by a break at T+280 s to an
alpha of 0.56 (+/-0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.89 (+0.23, -0.09). The
best-fitting absorption column is  consistent with the Galactic value
of 1.3 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.5 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.3 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.89 (+0.23, -0.09)

If the light curve continues to decay with a power-law decay index of
0.56, the count rate at T+24 hours will be 9.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.2 x
10^-13 (4.0 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/00666931.

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


GRB_name: GRB151210A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18683
SUBJECT: GRB 151210A: Swift-BAT refined analysis
DATE:    15/12/10 14:08:52 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), P. A. Evans (U Leicester),
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-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 151210A (trigger #666931)
(Evans, et al., GCN Circ. 18678).  The BAT ground-calculated position is
RA, Dec = 65.080, -71.225 deg, which is 
   RA(J2000)  =  04h 20m 19.1s 
   Dec(J2000) = -71d 13' 28.9" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
 
The mask-weighted light curve shows several peaks starting at ~T-55 sec,
with the brightest peaks at ~T+14 and ~T+38 sec, and ending at ~T+60sec.
T90 (15-350 keV) is 94.9 +- 10.4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-57.19 to T+48.36 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.82 +- 0.79, 
and Epeak of 49.4 +- 15.3 keV (chi squared 53.7 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+38.82 sec in the 15-150 keV band is
0.8 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.83 +- 0.15 (chi squared 59.89 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/666931/BA/


GRB_name: GRB151210A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18684
SUBJECT: GRB 151210A: Swift/UVOT Upper Limits
DATE:    15/12/10 15:12:29 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and P. A. Evans (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151210A
153 s after the BAT trigger (Evans et al., GCN Circ. 18678).
No optical afterglow consistent with the optical position
(Han et al., GCN Circ. 18679; Wiseman et al. GCN Circ. 18680)
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           153          302          147         >21.1
u_FC               311          560          246         >20.5
white              153         7227          805         >22.1
v                  640         7549          442         >20.3
b                  566         7023          510         >20.9
u                  311         6817          736         >20.8
w1                 690         6613          313         >20.4
m2                 840         6407          235         >19.8
w2                 616         7433          490         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.12 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB151212A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18685
SUBJECT: GRB 151212A: MAXI/GSC detection
DATE:    15/12/12 15:47:28 GMT
FROM:    Satoshi Nakahira at JAXA/MAXI  <nakahira.satoshi@jaxa.jp>

S. Nakahira(JAXA), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.),
Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (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 UT 2015-12-12T14:00:27.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (68.109 deg, -3.775 deg) = (04 32 26, -03 46 30) (J2000)
with statistical uncertainties of ~0.5 degree.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

The source showed a relatively soft energy spectrum, and a simple power-law fit gives a photon
index of 2.25 and the X-ray flux over the scan was 60 +- 12 mCrab (2-10keV, 1 sigma error).

There was no significant excess flux in the previous transit at UT 12:27
and in the next transit at 15:34 with an upper limit of 20 mCrab for each.

Detection Information:
http://maxi.riken.jp/alert/novae/7368487901/7368487901.htm


GRB_name: GRB151212A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18686
SUBJECT: GRB 151212A: Tiled Swift observations
DATE:    15/12/12 16:13:16 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 151212A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00050

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: GRB151212A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18687
SUBJECT: GRB 151212A: Swift-XRT afterglow detection
DATE:    15/12/12 20:48:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

T.G.R. Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U.
Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA), L.M. McCauley (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 151212A (Nakahira et al. GCN Circ. 18685) in a series of
observations tiled on the sky. The total exposure time is 1.3 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 437 s. The data were collected between T0+8.4 ks and T0+8.6 ks, and
are entirely in Photon Counting (PC) mode. 

An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow.  The position of this source
is RA, Dec=68.1521, -3.9615 which is equivalent to:

RA (J2000): 04:32:36.50
Dec(J2000): -03:57:41.3

with an uncertainty of 5.2 arcsec (radius, 90% confidence).  This
position is 11.5 arcmin from the MAXI position.  We cannot determine at
the present time whether the source is fading.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00050/index_1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00050.

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


GRB_name: GRB151212A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18688
SUBJECT: GRB 151212A: GROND Optical Afterglow Candidate
DATE:    15/12/13 09:07:28 GMT
FROM:    Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>

P. Wiseman (MPE Garching), S. Schmidl (TLS Tautenburg) and J. Greiner (MPE
Garching) report on behalf of the GROND team:

We observed the field of GRB 151212A (MAXI trigger; Nakahira et al., GCN
#18685) 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 03:27 UT on December 13, 2015, 13.5 hrs after the
GRB trigger. They were performed at an average seeing of 1.7" and at an
average airmass of 1.1, and through a significant layer of clouds.

We detect a single source at the border of the enhanced Swift-XRT error
circle (http://www.swift.ac.uk/xrt_positions/00020570/), which we propose
is the afterglow, at RA, Dec 68.150, -3.9626, which is equivalent to:

RA (J2000) = 04:32:36.1
Dec (J2000) = -03:57:45.3

with an uncertainty of 0.5" in each coordinate.

Based on the 72 min of total exposures in g'r'i'z'J and H, at a mid-time of
14.1 hrs after the burst, we measure the following preliminary magnitudes
and upper limits (AB magnitude system):

g' = 24.3 +/- 0.2 mag,
r' = 23.6 +/- 0.2 mag,
i' = 23.1 +/- 0.2 mag,
z' = 23.3 +/- 0.3 mag,
J > 21.2 mag, and
H > 20.7 mag.

We cannot say anything about fading at this time, but the power-law-like
magnitudes lead us to suspect this is the afterglow.

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


GRB_name: GRB151212A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18689
SUBJECT: GRB151212A: Swift/UVOT observations
DATE:    15/12/13 18:49:23 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <m.depasquale@ucl.ac.uk>

M. De Pasquale (PSU) and P. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began observing the field of MAXI-detected GRB 151212A
(Nahakira et al., GCN Circ. 18685) 42183 s after the trigger.
No optical afterglow consistent with the XRT source given by Evans
et al. (GCN Circ 18687) is detected in the UVOT exposures.

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

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

u              42183       48392          2939 >21.4

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: GRB151215A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18691
SUBJECT: GRB 151215A: Swift detection of a burst
DATE:    15/12/15 03:14:38 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. L. Gibson (U Leicester), J. A. Kennea (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:

At 03:01:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151215A (trigger=667392).  Swift slewed to the burst
after a short delay due to observing constraints. 
The BAT on-board calculated location is 
RA, Dec 93.595, +35.509 which is 
   RA(J2000) = 06h 14m 23s
   Dec(J2000) = +35d 30' 34"
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 5 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 03:04:18.1 UT, 169.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 93.58198, 35.51503 which is equivalent
to:
   RA(J2000)  = 06h 14m 19.68s
   Dec(J2000) = +35d 30' 54.1"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 43 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 4.02
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 173 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
0.40. 

Burst Advocate for this burst is S. L. Gibson (slg44 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: GRB151215A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18692
SUBJECT: GRB151215A: P60 Optical Afterglow Candidate
DATE:    15/12/15 03:50:49 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

S. B. Cenko (NASA/GSFC) reports on behalf of a larger collaboration:

We have imaged the location of GRB151215A (Gibson et al., GCN 18691) with the robotic Palomar 60 inch telescope.  Observations began at 3:07 UT (~ 6 minutes after the BAT trigger) and were obtained in the r', i', and z' filters.  

Just outside the XRT error circle, we find a fading source at (J2000) coordinates:

   RA: 06:14:20.22
   Dec: +35:30:57.2

Using calibration from nearby point sources, we find the object fades from i' = 17.47 +/- 0.05 mag at 3:07 UT to 18.58 +/- 0.15 mag at 3:24 UT.  Thus, we believe this quite likely to be the optical afterglow of GRB151215A.

Further observations are planned.


GRB_name: GRB151215A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18693
SUBJECT: GRB 151215A: Prompt enhanced Swift-XRT position
DATE:    15/12/15 03:52:01 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 151215A, we find an
enhanced XRT position of the afterglow: RA, Dec: 93.5840, 35.5162 which
is equivalent to:
   RA (J2000)  = 06 14 20.17
   Dec (J2000) = +35 30 58.3
with an uncertainty of 2.2 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/667392.

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: GRB151215A
Detection_method: GROND
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18694
SUBJECT: GRB 151215A: GROND Detection of the Optical/NIR Afterglow
DATE:    15/12/15 05:03:48 GMT
FROM:    Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>

P. Wiseman (MPE Garching), D. A. Kann (TLS Tautenburg), T. Schweyer,
and J. Greiner (MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 151215A (Swift trigger 667392; Gibson et al.,
GCN #18691) 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 04:04 UT on 15/12/2015, 63 minutes after the GRB
trigger, and are continuing. They were performed at an average seeing of
1.40" and at an average airmass of 2.5.

We found a single point source within the 2.2" Swift-XRT error circle
reported by Evans et al. (GCN #18693) and consistent with that of Cenko
GCN #18692), at:

RA (J2000) = 93.58416 = 06:14:20.2

Dec. (J2000) = +35.51596 = +35:30:57.5

with an uncertainty of 0.3" in each coordinate.

Based on the first 3.3 min of total exposures in g'r'i'z' and 3.0 min in
JHK, we estimate preliminary magnitudes (AB system) of

g' = 21.81 +/- 0.09 mag,
r' = 20.80 +/- 0.05 mag,
i' = 20.44 +/- 0.05 mag,
z' = 20.36 +/- 0.07 mag,
J = 19.6 +/- 0.2 mag,
H = 19.8 +/- 0.5 mag, and
K = 18.4 +/- 0.4 mag.

Given magnitudes are calibrated against SDSS as well as 2MASS field stars
and are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.34 mag in the direction of the
burst (Schlafly & Finkbeiner et al. 2011).


GRB_name: GRB151215A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18695
SUBJECT: GRB 151215A: Enhanced Swift-XRT position
DATE:    15/12/15 06:15:51 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 2236 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 151215A, 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 = 93.58409, +35.51608 which is equivalent
to:

RA (J2000): 06h 14m 20.18s
Dec (J2000): +35d 30' 57.9"

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: GRB151215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18696
SUBJECT: GRB 151215A: NOT spectroscopy and redshift
DATE:    15/12/15 10:15:44 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Xu (NAOC/CAS), N. R. Tanvir (Univ. Leicester), D. Malesani 
(DARK/NBI), J. P. U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), J. 
Saario (NOT and Univ. Turku) report on behalf of a larger collaboration:

We observed the optical afterglow (Cenko, GCN 18692; Wiseman et al., GCN 
18694) of GRB 151215A (Gibson et al., GCN 18691) using the Nordic 
Optical Telescope (NOT) equipped with the AlFOSC camera and spectrograph.

The optical afterglow is clearly visible in our images, and we measure 
its brightness on Dec 15.160 UT (0.81 hr after the GRB) to be R = 20.07 
+- 0.02 (Vega, assuming R = 16.31 for the USNO star at RA = 06:14:19.93, 
Dec = +35:31:06.0).

A sequence of three spectra of 1200 s each was carried out starting on 
Dec 15.176 UT (1.2 hr after the trigger), covering the wavelength range 
3200-9000 AA.

A wide trough is visible superimposed on the afterglow continuum, 
indicating Lyalpha absorption from neutral hydrogen. We also detect 
several narrow absorption features, which we interpret as due to, e.g., 
Si II, O I, Al II, all at a common redshift of z = 2.59. A preliminary 
fit to the Lyalpha profile yields an HI column density of 3x10^21 cm^-2, 
though establishing the system as a DLA.


GRB_name: GRB151215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18697
SUBJECT: GRB 151215A: MASTER  early OT detection and light curve
DATE:    15/12/15 12:19:35 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

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

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

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

report on behalf of the MASTER Team:

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 
34917111)  located in IAC was pointed to the  GRB151215A (Gibson et al. 
GCN 18691) 18 sec after notice time and 33 sec after trigger time at 2015-12-15 03:02:05 
UT with 10s exposition in two perpendicular polarization  planes.
We detect  OT  (Cenko et al GCN 18691, Wiseman et al. GCN 18694)  in first 
image with magnitude 17.8 +- 0.5 at a growing stage (midle time 38 sec 
after trigger).
We definetely see OT on all images  till 1500-th second.

The GRB optical light curve have a maximum at third image (110 s after 
triger time) with 17.0 +- 0.1 mag.
The automatic light curve in one polarization available here
http://master.sai.msu.ru/static/GRB151215A_v1.png
All magnitudes are unfiltered (0.2B+0.8R) with respect to number USNO B1.0 
stars.

This is preliminary results.
The message may be cited.


GRB_name: GRB151215A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18698
SUBJECT: GRB151215A: Swift/UVOT detection
DATE:    15/12/15 16:28:33 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <m.depasquale@ucl.ac.uk>

M. De Pasquale (UCL-MSSL) and S. L. Gibson (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151215A
174 s after the BAT trigger (Gibson et al., GCN Circ. 18691).
We detect the optical afterglow of GRB151215A within the XRT error
circle (Evans et al. GCN Circ. 18695), in the initial UVOT exposures.

The preliminary UVOT position is:
     RA  (J2000) =  06:14:20.25 =  93.58438 (deg.)
     Dec (J2000) = +35:30:57.4  =  35.51595 (deg.)
with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence).

The position of this source is consistent with those given by Cenko et al.
(GCN Circ. 18692) and GROND (Wiseman et al. GCN Circ. 18694).

There is no detection in UVOT uv filters, which is congruous with
the redshift z=2.6 of the event (Xu et al., GCN circ. 18696).

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 (Finding Chart)         174          323          147 19.05 Â± 0.14
white                         531         2586          362 20.59 Â± 0.19
v                             408         2636          253 19.67 Â± 0.35
b                             507         2561          233 20.85 Â± 0.42
u                             482         2536          233 >20.3
w1                            458         2512          233 >19.9
m2                            433         2651          225 >19.6
w2                            384         2612          253 >19.9

The magnitudes in the table are not corrected for the substantial Galactic
extinction due to the reddening of E(B-V) = 0.39 in the direction of the 
burst
(Schlegel et al. 1998).

-- 

Dr. Massimiliano De Pasquale
Research associate - Swift UVOT scientist
Mullard Space Science Laboratory, University College London


GRB_name: GRB151215A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18699
SUBJECT: GRB 151215A: Swift-BAT refined analysis
DATE:    15/12/15 22:29:18 GMT
FROM:    Tilan Ukwatta at LANL  <tilan.ukwatta@gmail.com>

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC),
N. Gehrels (GSFC), S. L. Gibson (U Leicester)
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 151215A (trigger #667392) (Gibson, et al., GCN
Circ. 18691). The BAT ground-calculated position is
RA, Dec = 93.622, 35.529 deg which is
   RA(J2000)  =  06h 14m 29.3s
   Dec(J2000) = +35d 31' 45.0"
with an uncertainty of 2.8 arcmin, (radius, sys+stat,
90% containment). The partial coding was 51%.

The mask-weighted light curve shows a multi-peak episode
starting ~T-15 sec, highest peak at ~T+0 sec, and the
episode ends around ~T+5 sec. T90 (15-350 keV)
is 17.8 +- 1.0 sec (estimated error including systematics).

The time-averaged spectrum from T-15.46 to T+3.13 sec is
best fit by a simple power-law model. The power law index
of the time-averaged spectrum is 1.99 +- 0.33. The fluence
in the 15-150 keV band is 3.1 +- 0.7 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.16 sec in
the 15-150 keV band is 1.6 +- 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/667392/BA/


GRB_name: GRB151215A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18700
SUBJECT: GRB 151215A: Swift-XRT refined Analysis
DATE:    15/12/16 03:14:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), A. Maselli  (INAF-IASFPA), L.M. McCauley
(PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU) and S.L. Gibson
report on behalf of the Swift-XRT team:

We have analysed 7.4 ks of XRT data for GRB 151215A (Gibson et al. GCN
Circ. 18691), from 180 s to 35.7 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. 18693).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.88 (+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 2.21 (+0.18, -0.17). The
best-fitting absorption column is  consistent with the Galactic value
of 4.0 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.5 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 4.0 x 10^21 cm^-2
Intrinsic column:    4 (+/-12) x 10^21 cm^-2 at z=2.59
Photon index:      2.21 (+0.18, -0.17)

If the light curve continues to decay with a power-law decay index of
0.88, the count rate at T+24 hours will be 3.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-13 (2.2 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/00667392.

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


GRB_name: GRB151210B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18701
SUBJECT: GRB 151210B: CALET Gamma-Ray Burst Monitor detection
DATE:    15/12/16 04:50:04 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

T. Sakamoto, A. Yoshida, I. Takahashi, Y. Kawakubo, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

The long-duration GRB 151210B (Fermi-GBM trigger #471401960) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 00:59:20.12 UT on 10 December 2015.  The burst 
was detected by all three CGBM instruments.  

The light curve of the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) shows the main 
peak starting from T0-3 sec, peaking at T0 and ending at T0+~40 sec.   
The T90 duration measured by the SGM data is 39 +- 3  sec (40-460 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm


GRB_name: GRB151215A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18702
SUBJECT: GRB 151215A: MITSuME Akeno optical upper limits
DATE:    15/12/16 11:13:41 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

Y.Muraki, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana,
Y.Yano, S.Harita, Y. Yatsu, and N. Kawai (Tokyo Tech)

report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151215A (S. L. Gibson et al., GCN Circular #18691) 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 2015-12-15 16:23:38 UT (~13.4 h after the burst).
We did not find any new point source within Swift/XRT circle in all three bands.

We obtained following limits for the magnitudes.

T0+[sec] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------
48230  17:48:09  5070  > 20.9  > 20.6  > 19.6
-------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18703
SUBJECT: GRB151215A: Early optical light curve from pt5m, La Palma
DATE:    15/12/16 15:03:14 GMT
FROM:    Liam K Hardy at U of Shffield  <liam.hardy@sheffield.ac.uk>

L. K. Hardy (Sheffield), S. P. Littlefair (Sheffield),
V. S. Dhillon (Sheffield, IAC), T. Butterley (Durham) and
R. W. Wilson (Durham) report:

The automated robotic telescope 'pt5m' (Hardy et al.
2015, MNRAS 454, 4316) on La Palma observed the field
of GRB 151215A (Gibson et al., GCN 18691) starting
at 03:02:42 UT on Dec 15, 53 seconds after the alert
notice release and 74 seconds after the GRB detection.

Observations comprised of 59 x 60-second exposures in
the Johnson/Cousins R-band with approximately 6-seconds
dead time between images. The final image was taken 65
minutes after the first.

We detect the optical counterpart to the GRB and observe a
rapidly declining light curve. Photometry is performed using
historical instrumental zeropoints. We measure an initial
magnitude of R = 17.13 +/- 0.04 (2 minutes after the GRB) and
a final magnitude of R = 20.8 +/- 0.7 (67 minutes after the GRB).

The light curve is available at:
http://slittlefair.staff.shef.ac.uk/images/grb151215.png


GRB_name: GRB151210B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18704
SUBJECT: GRB 151210B: Fermi GBM observation
DATE:    15/12/16 16:11:47 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

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

"At  00:59:16.643 UT on 10 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151210B (trigger 471401960 / 151210041)
which was also detected by the CALET Gamma-Ray Burst Monitor
(Sakamoto et al. 2015, GCN 18701).

The on-ground calculated location, using the GBM trigger
data, is RA = 294.0, DEC = -42.7 (J2000 degrees,
equivalent to 19 h 36 m, 42 d 42 '), with an uncertainty
of 3.4 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 13 degrees.


The GBM light curve shows an initial peak followed by a weaker emission episode
with a duration (T90) of about 37.6 s (50-300 keV).
The time-averaged spectrum from T0-4 s to T0+39 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.45 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 306 +/- 94 keV.

The event fluence (10-1000 keV) in this time interval is
(5.8 +/- 0.4)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.7 s in the 10-1000 keV band
is 2.4 +/- 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: GRB151216A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18705
SUBJECT: GRB 151216A: MAXI/GSC detection
DATE:    15/12/17 02:27:14 GMT
FROM:    Nobuyuki Kawai at Tokyo Tech  <nkawai@hp.phys.titech.ac.jp>

T. Kawamuro (Kyoto U.), H. Negoro (Nihon U.), S. Nakahira (JAXA), T. Sakamoto (AGU), 
H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA), 
T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), 
N. Kawai, M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech), 
A. Yoshida, Y. Kawakubo, H. Ohtsuki (AGU), 
H. Tsunemi, R.Imatani (Osaka U.), 
M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.), 
Y. Ueda, T. Hori, A. Tanimoto (Kyoto U.), 
Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (Chuo U.), 
M. Yamauchi, D. Itoh, K. Furuya (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 UT 2015-12-16T19:03:15.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (323.762 deg, 24.765 deg) = (21 35 02, +24 45 54) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.32 deg and 0.25 deg, respectively.
The roll angle of long axis from the north direction is 162.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 140 +- 25 mCrab
(4-10keV, 1 sigma error).

Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(322.253 deg, 24.688 deg) = (21 29 00, +24 41 17) (J2000)
(322.468 deg, 24.080 deg) = (21 29 52, +24 04 46) (J2000)
(324.455 deg, 24.613 deg) = (21 37 49, +24 36 46) (J2000)
(324.259 deg, 25.227 deg) = (21 37 02, +25 13 37) (J2000)

There was no significant excess flux in the previous transit at UT 17:30
and in the next transit at 20:35 UT with an upper limit of 20 mCrab for each.

Detection Information:
http://maxi.riken.jp/alert/novae/7372632950/7372632950.htm <http://maxi.riken.jp/alert/novae/7372632950/7372632950.htm> 


GRB_name: GRB151212B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18706
SUBJECT: GRB 151212B: CALET Gamma-Ray Burst Monitor detection
DATE:    15/12/17 07:53:13 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

I. Takahashi, A. Yoshida, T. Sakamoto, Y. Kawakubo, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

The long-duration GRB 151212B (Fermi-GBM trigger #471576728) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 01:32:04.68 UT on 12 December 2015.  The clear 
burst signal was detected by the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) which 
is a scintillation detector utilized a BGO crystal.  Due to a large incident angle 
of the event, no signal was detected by the Hard X-ray Monitor (HXM; 7 keV - 1 MeV) 
which is a scintillation detector composed of a LaBr3(Ce) crystal.

The light curve of the SGM shows the main peak starting from T0, peaking 
at T0+1 sec and ending at T0+4 sec.   The T90 duration measured by the SGM 
data is 3.5 +- 0.5  sec (40-460 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm


GRB_name: GRB151215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18707
SUBJECT: GRB151215A: Continued P60 Observations
DATE:    15/12/17 15:30:18 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

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

We imaged the field of the optical afterglow (Cenko et al., GCN 18692) of GRB151215A (Gibson et al., GCN 18691) with the robotic Palomar 60 inch telescope.  Observations were obtained in the r', i', and z' filters beginning at 3:41 UT on 16 December 2015 (1.0 d after the Swift trigger).  We do not detect any emission at the location of the afterglow in any filter.  Using nearby point sources from SDSS for calibration, we calculate an upper limit of i' > 21.7 mag at a mean epoch of 1.04 d after the burst.


GRB_name: GRB151215A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18708
SUBJECT: GRB 151215A: TSHAO optical observations
DATE:    15/12/17 17:16:14 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin 
(Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) 
report on behalf of larger GRB follow-up collaboration:

We observed the field of GRB 151215A (Gibson et al., GCN 18691)  with 
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory 
starting on Dec. 15 (UT) 16:47:23.  We obtained several images in R 
filter.  The afterglow  (Cenko, GCN 18692)  is detected  in a combined 
image. Preliminary photometry of the afterglow is following

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

2015-12-15 16:47:23    0.61190  R       21*300  22.1   0.3

The photometry is based on nearby SDSS stars.








GRB 151215A
observatory TSHAO
date 2015-12-15
UT start 16:47:23.69
t-T0 0.61190 d
exptime 21*300 s
filter R
OT 22.07 +/- 0.38 (Ð²Ñ‹Ñ‡Ð¸Ñ‚Ð°Ð½Ð¸ÐµÐ¼ Ð¿Ð¾Ñ‚Ð¾ÐºÐ¾Ð²)
uplim 22.4
fwhm 2.4 "


GRB_name: GRB151221A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18711
SUBJECT: GRB 151221A: INTEGRAL detection of a short burst or possible SGR
DATE:    15/12/21 10:18:14 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 about 50 ms has been detected by IBAS in the 
IBIS/ISGRI data at 02:51:12.7 UT of December 21, 2015 with a significance 
below the threshold for automatic alert delivery (IBAS Weak Alert n.7313)

The refined coordinates (J2000) are:

R.A.=  293.7327 deg
DEC.=  21.8843 deg


with an uncertainty of 2 arcmin (90% c.l.).

The burst had a fluence of about 4e-8 erg/cm2 (20-200 keV, 0.1-s 
integration time).

The soft spectrum, short duration, low galactic latitude and position 
inside the supernova remnant G57.2+0.8 suggest taht this event could be 
due to a new Soft Gamma-ray Repeater.

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


GRB_name: GRB151222A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18715
SUBJECT: GRB 151222A: Fermi GBM detection
DATE:    15/12/22 17:10:12 GMT
FROM:    Hoi-Fung Yu at MPE  <sptfung@mpe.mpg.de>

Hoi-Fung Yu (MPE) reports on behalf of the Fermi GBM Team:

"At 08:10:13.62 UT on 22 Dec 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151222A (trigger 472464617 / 151222340).
The on-ground calculated location, using the GBM trigger data, 
is RA = 355, Dec = 36.7 (J2000 degrees, equivalent to 23h 40m, 36d 42'), 
with an uncertainty of 3 degrees (radius, 1-sigma containment, statistical 
only; there is additionally a systematic error which we have characterized 
as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and 
a small tail suffering a larger than 10 deg systematic error. 
[Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time 
is 117 degrees.

The GBM light curve consists of two short pulses with a duration (T90) of 
about 0.8 s (50-300 keV). The time-averaged spectrum from T0-0.256 s 
to T0+0.768 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.68 +/- 0.09 and
the cutoff energy, parameterized as Epeak, is 1490 +/- 270 keV.

The event fluence (10-1000 keV) in this time interval is
(2.36 +/- 0.13)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.256 s in the 10-1000 keV band
is 12.9 +/- 1.9 ph/s/cm^2.

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


GRB_name: GRB151222A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18720
SUBJECT: IPN Triangulation of GRB 151222A (short/hard)
DATE:    15/12/24 12:28:19 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

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,

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

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

The short-duration, hard-spectrum GRB 151222A has been detected
by Konus-Wind, Fermi (GBM: Hoi-Fung Yu GCN Circ. 18715),
INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND), so far,
at about 29414 s UT (08:10:14).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   354.942 (23h 39m 46s) +34.095 (+34d 05' 44")
  Corners:
   355.188 (23h 40m 45s) +34.534 (+34d 32' 01")
   354.558 (23h 38m 14s) +33.943 (+33d 56' 34")
   354.701 (23h 38m 48s) +33.652 (+33d 39' 07")
   355.328 (23h 41m 19s) +34.244 (+34d 14' 39")
  ---------------------------------------------
The error box area is 792 sq. arcmin, and its maximum
dimension is 58 arcmin (the minimum one is 16.8 arcmin).
The Sun distance was 98 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB151222_T29415/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming 
GCN Circular.


GRB_name: GRB151222A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18723
SUBJECT: Konus-Wind observation of GRB 151222A
DATE:    15/12/25 12:52:22 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, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration, hard-spectrum GRB 151222A
(Fermi GBM detection: Hoi-Fung Yu, GCN Circ. 18715;
IPN triangulation: Hurley, et al., GCN Circ. 18720)
triggered Konus-Wind at T0=29415.138  s UT (08:10:15.138).

The burst light curve shows a double-peaked structure
with a total duration of ~0.5 s.

As observed by Konus-Wind, the burst
had a fluence of 2.20(-0.23,+0.28)x10^-6 erg/cm2
and a 16-ms peak flux, measured from T0+0.048 s,
of 1.03(-0.11,+0.13)x10^-5 erg/cm2/s
(both in the 20 - 1500 keV energy range).

Since a major fraction of the burst counts was accumulated
before the trigger, the spectral analysis was performed using
the KW 3-channel light curve data.
Modeling the 3-channel time-integrated spectrum
(measured from T0-0.434 s to T0+0.094 s)
by the cutoff power law yields the following model parameters:
the photon index alpha=0.13(-0.44,+0.64),
and the peak energy Ep=625(-118,+220) keV.

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.ru/LEA/GRBs/GRB151222_T29415/


GRB_name: GRB151225A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18724
SUBJECT: GRB 151225A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB
DATE:    15/12/26 02:37:37 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kawakubo, A. Yoshida, T. Sakamoto, I. Takahashi, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

A possible short-duration GRB 151225A (trigger #1135105601) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 19:09:10.34 UT on 25 December 2015.  The clear 
burst signal was detected by all three CGBM instruments.  

The light curve of the SGM shows a double peak structure.  The initial spike 
starts and peaks around T0.  The second peak starts around T0+0.5 sec, peaks 
around T0+0.7 sec and ending around T0+1.5 sec.  Above 500 keV band, the first 
peak looks insignificant, instead the 2nd peak is clearly visible.  Based on the 
light curve inspection, the signal is clearly visible up to ~1.5 MeV.  Low energy 
data show no significant soft extended emission above ~7 keV.  The T90 duration 
measured by the SGM data is 1.87 +- 0.13 sec (40-450 keV).  

Identification of this possible short event by other spacecraft is strongly encouraged.  


GRB_name: GRB151212A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18725
SUBJECT: GRB 151212A iTelescope observation
DATE:    15/12/27 04:48:03 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU) 

We observed the field of GRB 151212A detected by MAXI (Nakahira et al., GCN Circ. 18685) 
with the iTelescope.Net (http://www.itelescope.net) T18 (Plane Wave CDK) telescope located 
at the AstroCamp Observatory (Nerpio, Spain).  20 images of 60 sec exposures were taken 
in the Red filter starting from December 12 22:43:00 (UT) about 8.7 hours after the trigger 
and stopped on December 12 23:17:03 (UT).  We do not detect the optical afterglow both in the 
individual images and the stacked image at the X-ray afterglow position 
(Roegiers et al., GCN Circ. 18687).  The estimated five sigma upper limit of the combined 
image (total exposure of 1200 sec) is ~17.0 using the USNO-B1 catalog.


GRB_name: GRB151227A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18726
SUBJECT: GRB 151227A: Fermi GBM detection
DATE:    15/12/27 10:53:33 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

P Veres (UAH) and Kilian Toelge (MPE)
report on behalf of the Fermi GBM Team:


"At 01:44:07.69 UT on 27 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151227A (trigger 472873451 / 151227072).


The on-ground calculated location, using the GBM trigger
data, is RA = 205.5, DEC = +65.9 (J2000 degrees,
equivalent to 13h 42m, 65d 52'), with an uncertainty
of 1.5 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

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

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the best location is 32 degrees.

The GBM light curve consists of a single pulse
with a duration (T90) of about 3.4 s (50-300 keV).
The time-averaged spectrum from T0 to T0 + 8.9 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.91 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 155 +/- 7 keV.

The event fluence (10-1000 keV) in this time interval is
(5.0 +/- 0.1)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.8 s in the 10-1000 keV band
is 20.5 +/- 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: GRB151227B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18727
SUBJECT: GRB 151227B: Fermi GBM detection
DATE:    15/12/27 16:05:37 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

Kilian Toelge (MPE) and Elisabetta Bissaldi (Politecnico di Bari) 
report on behalf of the Fermi GBM Team: 


"At 05:13:48.86 UT on 27 December 2015, the Fermi Gamma-Ray Burst Monitor 
triggered and located GRB 151227B (trigger 472886032 / 151227218). 
The on-ground calculated location, using the GBM trigger data, 
is RA = 287.9, DEC = 31.9 (J2000 degrees, 
equivalent to 19h 11m, 31d 54'), with an uncertainty 
of 1 degree (radius, 1-sigma containment, 
statistical only; there is additionally a systematic error 
which we have characterized as a core-plus-tail model, with 90% of 
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg 
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). 

The angle from the Fermi LAT boresight at the GBM trigger time is 90 degrees. 

The GBM light curve consists of three pulses 
with a duration (T90) of about 43.0 s (50-300 keV). 
The time-averaged spectrum from T0+20.0 s to T0+49.7 s 
is best fit by a Band function with Epeak = 310 +/- 21 keV, 
alpha = -1.27 +/- 0.02, and beta = -2.17 +/- 0.08. 

The event fluence (10-1000 keV) in this time interval 
is (8.94 +/- 0.09)E-6 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+29.8 s in the 8-1000 keV band 
is 36.1 +/- 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: GRB151228A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18731
SUBJECT: GRB 151228A: Swift detection of a short burst
DATE:    15/12/28 03:14:53 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

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

At 03:05:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151228A (trigger=668543).  Swift did not slew to the burst. 
The BAT on-board calculated location is 
RA, Dec 214.004, -17.689, which is 
   RA(J2000)  =  14h 16m 01s
   Dec(J2000) = -17d 41' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single spike
structure with a duration of about 0.6 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift cannot slew to the BAT position. 
There will thus be no XRT or UVOT data for this trigger. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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: GRB151228A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18736
SUBJECT: GRB 151228A: Fermi GBM observation
DATE:    15/12/28 16:41:59 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

Elisabetta Bissaldi (Politecnico di Bari), Binbin Zhang (UAH) and
Peter Veres (UAH)
report on behalf of the Fermi GBM Team:

"At 03:05:12.46 UT on 28 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151228A (trigger 472964716 / 151228129),
which was also detected by the Swift/BAT
(Ukwatta et al. 2015, GCN 18731).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 117 degrees.


The GBM light curve consists of a single peak
with a duration (T90) of about 0.26 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.32 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.41 +/- 0.23 and
the cutoff energy, parameterized as Epeak, is 747 +/- 193 keV.

The event fluence (10-1000 keV) in this time interval is
(9.2 +/- 0.8)E-7 erg/cm^2. The 64 ms peak photon flux measured
starting from T0-0.06 s in the 10-1000 keV band
is 12.4 +/- 2.0 ph/s/cm^2.


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


GRB_name: GRB151228B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18739
SUBJECT: GRB 151228B: Swift detection of a burst with an optical detection
DATE:    15/12/28 23:03:29 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),
F. E. Marshall (NASA/GSFC), L. M. McCauley (PSU) and
K. L. Page (U Leicester) report on behalf of the Swift Team:

At 22:47:14 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151228B (trigger=668641).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 344.441, +8.076, which is 
   RA(J2000)  =  22h 57m 46s
   Dec(J2000) = +08d 04' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows FRED-like peak
structure with a duration of about 40 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 22:48:04.4 UT, 49.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
344.4247, 8.0816 which is equivalent to:
   RA(J2000)  = 22h 57m 41.93s
   Dec(J2000) = +08d 04' 53.7"
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This
location is 61 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 5.74
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 6.74e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 57 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =  22:57:41.85 = 344.42437
  DEC(J2000) = +08:04:54.0  =   8.08166
with a 90%-confidence error radius of about 0.80 arc sec. This position is 3.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.74 with a 1-sigma error of about  0.17. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.06. 

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: GRB151228B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18743
SUBJECT: GRB 151228B: Enhanced Swift-XRT position
DATE:    15/12/29 03:40:07 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 2601 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 151228B, 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 = 344.42460, +8.08148 which is equivalent
to:

RA (J2000): 22h 57m 41.90s
Dec (J2000): +08d 04' 53.3"

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

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

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


GRB_name: GRB151229A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18745
SUBJECT: GRB 151229A: Swift detection of a short burst
DATE:    15/12/29 07:09:40 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

D. Kocevski (NASA/GSFC/ORAU), A. Y. Lien (GSFC/UMBC),
K. L. Page (U Leicester) and T. N. Ukwatta (LANL) report on behalf of
the Swift Team:

At 06:50:27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 151229A (trigger=668689).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 329.380, -20.729 which is 
   RA(J2000) = 21h 57m 31s
   Dec(J2000) = -20d 43' 42"
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 1.5 sec.  The peak count rate
was ~7000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 06:51:54.9 UT, 86.9 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 329.3703,
-20.7325 which is equivalent to:
   RA(J2000)  = 21h 57m 28.87s
   Dec(J2000) = -20d 43' 56.9"
with an uncertainty of 2.0 arcseconds (radius, 90% containment). This
location is 35 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.71 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 7.6
(+2.59/-2.28) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 90 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 D. Kocevski (dankocevski 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: GRB151228A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18746
SUBJECT: GRB 151228A: T60 observations
DATE:    15/12/29 07:59:13 GMT
FROM:    Eda Sonbas at NASA/GSFC  <edasonbas@gmail.com>

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



We observed the field of GRB 151228A (Ukwatta et al., GCN #18731) with the
0.60 meter T60 telescope (TUBITAK National Observatory, Antalya - Turkey),
starting on December 28, 03:06:43.45 UT (~ 90 sec after the trigger). We
obtained 3 x 60 s + 2 x 20 s exposures with R filters under good weather
conditions.


We do not detect an optical afterglow within the reported BAT error circle
down to a limiting magnitude of >~17 (2-sigma) in the combined R band image.


We thank to TUBITAK National Observatory for a partial support in using T60
telescope with project number 13DT60-539 and technical support.


GRB_name: GRB151228A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18747
SUBJECT: GRB 151228A: MITSuME Akeno optical upper limits
DATE:    15/12/29 09:15:22 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

Y.Saito, T.Fujiwara, T. Yoshii, Y. Tano, Y. Tachibana,
Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)

report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151228A (T. N. Ukwatta et al., GCN Circular #18731) 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 2015-12-28 19:25:49 UT (~16.3 h after the burst).
We did not find any new point source within BAT circle in all three bands.

We obtained following limits for the magnitudes.

T0+[sec]       MID-UT     T-EXP[sec]      g'        Rc             Ic
--------------------------------------------------------------------------------------
58837         20:04:32      4200         > 20.0     > 20.0     > 19.3
---------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151228B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18749
SUBJECT: GRB 151228B: Swift-XRT refined Analysis
DATE:    15/12/29 10:11:53 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 10 ks of XRT data for GRB 151228B (Lien et al. GCN
Circ. 18739), from 40 s to 29.0 ks after the  BAT trigger. The data
comprise 194 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. 18743).

The late-time light curve (from T0+4.7 ks) can be modelled with a
power-law decay with a decay index of alpha=0.68 (+0.22, -0.21).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.43 (+/-0.08). The
best-fitting absorption column is  1.78 (+0.21, -0.20) x 10^21 cm^-2,
in excess of the Galactic value of 5.7 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.94 (+0.14, -0.12)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.4 x 10^-11 (3.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.7 (+2.3, -0.0) x 10^20 cm^-2
Galactic foreground: 5.7 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.94 (+0.14, -0.12)

If the light curve continues to decay with a power-law decay index of
0.68, the count rate at T+24 hours will be 8.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-13 (3.2 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/00668641.

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


GRB_name: GRB151229A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18750
SUBJECT: GRB 151229A: Enhanced Swift-XRT position
DATE:    15/12/29 10:17:20 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 609 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 151229A, 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 = 329.36981, -20.73203 which is equivalent
to:

RA (J2000): 21h 57m 28.76s
Dec (J2000): -20d 43' 55.3"

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

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

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


GRB_name: GRB151229A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18751
SUBJECT: GRB 151229A: Swift-BAT refined analysis
DATE:    15/12/29 14:19:16 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), D. Kocevski (NASA/GSFC/ORAU),
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-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151229A (trigger #668689)
(Kocevski, et al., GCN Circ. 18745).  The BAT ground-calculated position is
RA, Dec = 329.363, -20.732 deg, which is 
   RA(J2000)  =  21h 57m 27.1s 
   Dec(J2000) = -20d 43' 56.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 51%.
 
The mask-weighted light curve shows  single peak starting at ~T-0.1 sec,
peaking at ~T+0.1 sec, and ending at ~T+1.7 sec.  T90 (15-350 keV) is
1.78 +- 0.44 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.11 to T+2.34 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.84 +- 0.10.  The fluence in the 15-150 keV band is 5.9 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.11 sec in the 15-150 keV band
is 7.2 +- 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/668689/BA/


GRB_name: GRB151228B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18752
SUBJECT: GRB 151228B: Swift-BAT refined analysis
DATE:    15/12/29 14:29:59 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), 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. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+243 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 151228B (trigger #668641)
(Lien, et al., GCN Circ. 18739).  The BAT ground-calculated position is
RA, Dec = 344.431, 8.081 deg, which is 
   RA(J2000)  =  22h 57m 43.4s 
   Dec(J2000) = +08d 04' 52.4" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows a FreD-like peak starting at ~T-10 sec,
peaking at ~T+3 sec, and ending at ~T+65 sec.  T90 (15-350 keV) is
48.0 +- 16.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-12.56 to T+67.44 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.09 +- 0.34, 
and Epeak of 78.1 +- 27.0 keV (chi squared 52.3 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+10.94 sec in the 15-150 keV band is
1.0 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.66 +- 0.08 (chi squared 61.6 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/668641/BA/


GRB_name: GRB151229A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18753
SUBJECT: GRB 151229A: Swift/UVOT observations
DATE:    15/12/29 14:37:16 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <m.depasquale@ucl.ac.uk>

M. De Pasquale (UCL-MSSL) and D. Kocevski (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151229A
90 s after the BAT trigger (Kocevski et al., GCN Circ. 18745).
No optical afterglow consistent with the XRT position (Osborne et al.
GCN Circ. 18750) 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            90          240          147         >20.0
u_FC               302          552          246         >19.3
white               90         5493          378         >20.5
v                  632         5904          413         >18.8
b                  558         5288          236         >19.5
u                  302         6513          653         >19.8
w1                 681         6314          413         >19.7
m2                4474         6108          393         >19.9
w2                4064         5699          393         >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).

-- 

Dr. Massimiliano De Pasquale
Research associate - Swift UVOT scientist
Mullard Space Science Laboratory, University College London


GRB_name: GRB151228A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18754
SUBJECT: GRB 151228A: Swift-BAT refined analysis
DATE:    15/12/29 15:37:40 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), 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-239 to T+963 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 151228A (trigger #668543)
(Ukwatta, et al., GCN Circ. 18731).  The BAT ground-calculated position is
RA, Dec = 214.017, -17.665 deg, which is 
   RA(J2000)  =  14h 16m 04.0s 
   Dec(J2000) = -17d 39' 52.7" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows a single spike starting at ~T-0.05,
peaking at ~T+0.03, and ending at ~T+0.3.  T90 (15-350 keV) is
0.27 +- 0.01 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.036 to T+0.276 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.85 +- 0.20.  The fluence in the 15-150 keV band is 8.4 +- 1.1 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.38 sec in the 15-150 keV band
is 0.9 +- 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/668543/BA/


GRB_name: GRB151228B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18755
SUBJECT: GRB 151228B: Fermi GBM observation
DATE:    15/12/29 16:58:45 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P Veres (UAH) reports on behalf of the Fermi GBM Team:

"At 22:47:12.59 UT on 28 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151228B (trigger 473035636 / 151228949).
which was also detected by the Swift/BAT (Lien et al. 2015, GCN 18739).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 107 degrees.

The GBM light curve shows of a single pulse
with a duration (T90) of about 29 s (50-300 keV). There was a
Solar flare coincident with this GRB which affected the low
energy channels of GBM. For this reason the spectral analysis
was carried out for photon energies above 40 keV.
The time-averaged spectrum from T0-6.1 s to T0+21.5 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.1 +/- 0.4 and
the cutoff energy, parameterized as Epeak, is 93 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(3.6 +/- 0.4)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.3 s in the 10-1000 keV band
is 7.6 +/- 0.9 ph/s/cm^2.

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

[GCN OPS NOTE(29dec15): Per author's request, the "29A" in the Subject-line
was changed to "28B", and the "2008"  was changed to "2015" in the citation.]


GRB_name: GRB151229A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18756
SUBJECT: GRB 151229A: Fermi GBM observation
DATE:    15/12/29 17:07:57 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 06:50:27.95 UT on 29 December 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151229A (trigger 473064631 / 151229285 ),
which was also detected by the Swift/BAT (Kocevski et al. 2015, GCN 18745)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 53.4 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 3.5 s (50-300 keV).
The time-averaged spectrum from T0-0.256: s to T0+1.280 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.19 (+0.10/-0.09) and
the cutoff energy, parameterized as Epeak, is 97.1 (+10.3/-8.3) keV

The event fluence (10-1000 keV) in this time interval is
(9.4 +/- 0.5)E-07 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-0.128 s in the 10-1000 keV band
is 11.0 +/- 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: GRB151229A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18757
SUBJECT: GRB 151229A: Swift-XRT refined Analysis
DATE:    15/12/29 20:52:00 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

K.L. Page (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU), T.G.R. Roegiers (PSU), C. Pagani (U. Leicester), A.P.
Beardmore (U. Leicester) and D. Kocevski report on behalf of the
Swift-XRT team:

We have analysed 7.4 ks of XRT data for GRB 151229A (Kocevski et al.
GCN Circ. 18745), from 73 s to 32.8 ks after the  BAT trigger. The data
comprise 67 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. 18750).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.832 (+/-0.021).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.04 (+0.15, -0.14). The
best-fitting absorption column is  7.2 (+1.1, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 2.7 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 4.3 x 10^-11 (7.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.2 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 11.4 sigma
Photon index:      2.04 (+0.15, -0.14)

If the light curve continues to decay with a power-law decay index of
0.832, the count rate at T+24 hours will be 0.023 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.8 x
10^-13 (1.8 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00668689.

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


GRB_name: GRB151228B
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18758
SUBJECT: GRB 151228B: MITSuME Akeno optical upper limits
DATE:    15/12/29 21:44:48 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

Y.Muraki, T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana,
Y.Yano, S.Harita, Y. Yatsu, and N. Kawai (Tokyo Tech)

report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151228B (A. Y. Lien et al., GCN Circular #18739) 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 2015-12-29 09:55:19 UT (~11.1 h after the burst).
We did not find any new point source within Swift/XRT circle in all three bands.

We obtained following limits for the magnitudes.

T0+[sec] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------
40085  10:37:06  2507  > 20.9  > 20.6  > 19.6
-------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151229A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18760
SUBJECT: GRB 151229A Swift-BAT Spectral lag analysis
DATE:    15/12/29 23:11:56 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC) for the Swift-BAT Team:

We report the spectral lag analysis for GRB 151229A (Kocevski, et al.,
GCN Circ. 18745, & Lien 18751) based on the BAT data.  Using 8-ms binned light curve,
the spectral lag for the 25-50 keV to 100-300 keV bands is -47.6 +/-31 ms and
+12 +/-24 for the 15-25 to 50-100 bands.  Although the errors are large,
the values are marginally consistent with zero, therefore we believe
this burst belongs to a short burst category, although we can not rule out
the long burst possibility.  There is no evidence for extended emission. 


GRB_name: GRB151229A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18761
SUBJECT: GRB 151229A: MITSuME Okayama upper limits
DATE:    15/12/30 00:02:58 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 151229A (Kocevski et al., GCNC 18745)
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 2015-12-29 09:07:26 UT (~2.3h after the burst).
We did not find any new point source within the enhanced XRT circle
(Osborne et al., GCNC 18750) in all the three bands.

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

#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.11774    09:39:59    2940.0   >18.7  >18.7  >18.2
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB151229A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18765
SUBJECT: GRB 151229A: MITSuME Akeno optical upper limits
DATE:    15/12/30 07:08:42 GMT
FROM:    Taketoshi Yoshii at Tokyo Tech  <yoshii.t.ac@m.titech.ac.jp>

Y.Saito, T.Fujiwara, T. Yoshii, Y. Tano, Y. Tachibana,
Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 151229A (D. Kocevski et al., GCN Circular #18745) 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 2015-12-29 08:56:00 UT (~2.1 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
-------------------------------------------------------------------------------------------------
7533       09:20:52            2700           > 19.5        > 19.4        > 18.6
-------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB151228B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18766
SUBJECT: GRB 151228B: Swift/UVOT Detection
DATE:    15/12/30 07:45:04 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A.A. Breeveld (UCL-MSSL), S.W.K. Emery (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 151228B
49 s after the BAT trigger (Lien et al., GCN Circ. 18739).
A fading source consistent with the XRT position (Goad et al. GCN Circ. 
18743) is detected in the initial UVOT exposures in the white filter.

The preliminary UVOT position is:
     RA  (J2000) =  22:57:41.87 = 344.42446 (deg.)
     Dec (J2000) = +08:04:53.7  =   8.08159 (deg.)
with an estimated uncertainty of 0.58 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               70          220          147         19.62 Â± 0.19
v                   49         6132          306        >19.2
b                  537         5514          274        >20.0
u                  282         5309          520        >20.1
w1                 661         6373          303        >20.1
m2                6137         6337          197        >19.9
w2                1386         5927          216        >20.8

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).


GRB_name: GRB151228A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18770
SUBJECT: GRB 151228A: Swift-XRT refined Analysis
DATE:    15/12/30 13:33:24 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), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), C. Pagani
(U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team:

We have analysed xx ks of XRT data for GRB 151228A (Ukwatta et al. GCN
Circ. 18731), from xx to 0 s after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. We cannot determine at the
present time whether the source is fading.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00668543.

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


GRB_name: GRB151228A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18772
SUBJECT: GRB 151228A: Correction to GCN 18770
DATE:    15/12/30 13:49:06 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

We apologise for the incomplete nature of GCN 18770, which was
automatically sent out in error. The correct information is given below:

We have analysed 2.2 ks of XRT data for GRB 151228A (Ukwatta et al., GCN
Circ. 18731), from 178.6 to 196.5 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. No X-ray source is detected in or
near to the BAT refined error circle (Barthelmy et al., GCN Circ. 18754),
to a 3-sigma upper limit of 7x10^-3 count s^-1, corresponding to an
approximate observed flux of 3x10^-13 erg cm^-2 s^-1.

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


GRB_name: GRB151227B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18773
SUBJECT: IPN Triangulation of GRB 151227B
DATE:    15/12/30 14:00:22 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

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

S. Golenetskii, R. Aptekar, 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,

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

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

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

The long-duration GRB 151227B has been detected by Fermi (GBM: Toelge 
and Bissaldi, GCN Circ. 18727), Konus-Wind, Mars-Odyssey (HEND), 
INTEGRAL (SPI-ACS), and Swift (BAT), so far, at about 18829 s UT 
(05:13:49). 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:
   290.284 (19h 21m 08s) +35.415 (+35d 24' 55")
  Corners:
   290.279 (19h 21m 07s) +35.990 (+35d 59' 22")
   290.052 (19h 20m 13s) +36.037 (+36d 02' 12")
   290.288 (19h 21m 09s) +34.841 (+34d 50' 26")
   290.512 (19h 22m 03s) +34.792 (+34d 47' 32")
  ---------------------------------------------
The error box area is 759 sq. arcmin, and its maximum
dimension is 1.3 deg (the minimum one is 10.4 arcmin).
The Sun distance was 60 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB151227_T18827/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming 
GCN Circular.


GRB_name: GRB151227B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  18781
SUBJECT: Konus-Wind observation of GRB 151227B
DATE:    15/12/31 08:50:48 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, intense GRB 151227B
(Fermi GBM detection: Toelge & Bissaldi, GCN 18727;
IPN Triangulation: Hurley et al., GCN 18773)
triggered Konus-Wind at T0=18827.479 s UT (05:13:47.479).

The burst light curve shows three emission episodes with a total 
duration of ~48 s.
The emission is seen up to ~15 MeV.

As observed by Konus-Wind, the burst
had a fluence of 6.49(-0.72,+0.72)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+29.728 s,
of 1.11(-0.20,+0.19)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+43.776 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.19(-0.08,+0.10),
the high energy photon index beta = -2.11(-0.18,+0.11),
the peak energy Ep = 228(-40,+46) keV,
chi2 = 110/97 dof.

The spectrum near the peak count rate
(measured from T0+24.832 to T0+35.584 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.25(-0.05,+0.05),
the high energy photon index beta = -2.57(-1.09,+0.28),
the peak energy Ep = 353(-44,+52) keV,
chi2 = 111/93 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB151227_T18827/

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


