GRB 131128A

E. Sonbas (NASA/GSFC/Adiyaman Univ.), W. H. Baumgartner (GSFC/UMBC),
M. G. Bernardini (INAF-OAB), S. B. Cenko (GSFC),
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), S. T. Holland (STScI),
A. Y. Lien (NASA/GSFC/ORAU), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. H. Siegel (PSU),
R. L. C. Starling (U Leicester) and E. Troja (NASA/GSFC/UMCP) report
on behalf of the Swift Team:

At 15:06:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 131128A (trigger=579683).  Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 355.323, +31.279 which is
   RA(J2000) = 23h 41m 18s
   Dec(J2000) = +31d 16' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  The BAT light curve showed a single FRED peak
structure with a duration of about 3 sec with a possible precursor
around T-8.  The peak count rate was ~3000 counts/sec (15-350 keV),
at ~0 sec after the trigger.

The XRT began observing the field at 15:07:51.3 UT, 86.8 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 355.3084,
31.3057 which is equivalent to:
   RA(J2000)  = 23h 41m 14.02s
   Dec(J2000) = +31d 18' 20.7"
with an uncertainty of 2.2 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.

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 5.16
x 10^20 cm^-2 (Kalberla et al. 2005).

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 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 0.07.

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.)

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

We observed the fields of GRB 131128A (Sonbas et al., GCN 15533
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 ),
using the 1m telescope located on Mt. Nanshan, Xinjiang, China.
Observations started 880s after the Swift trigger and a series of
R-band frames were obtained.

An optical source is clearly detected at coordinates:

R.A. (J2000) = 23:41:13.75
Dec.(J2000) = +31:18:23.14

Error Radius: ~1 arcsec

which is consistent with the SPER XRT position of this burst
(http://www.swift.ac.uk/sper/), thus it's likely the afterglow of the
GRB.

Note that there is a very bright star (r=14.76 mag from SDSS) just a
few arcsec away from this optical transient. Observations are ongoing.

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

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


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


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

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

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

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


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB131128.63 12 sec  after 
notice time and 315 sec after GRB time at 2013-11-28 15:11:39.707 UT. On 
our first (60s exposure) set we haven`t found optical transient  within 
XRT SWIFT error-box.

There is bright star near XRT position USNO-A2.0 1200-19996598 R_mag ~ 12.
The 5-sigma upper limit has been about 17.1 mag.
We do not see OT at the Nanshan afterglow candidate position (Xu et al., 
GCN15535
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 ). 
The message may be cited.

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

Continued observations of GRB 131128A, 120s each for the beginning and
240s each for the subsequent all in R-band, at the Nanshan observatory
show that the afterglow candidate in Xu et al (GCN 15535
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 ) has decayed
by more than 1 magnitude at 1.95 hr after the Swift trigger,
calibrated with the same nearby SDSS stars. The initial magnitude is
R~19 mag in GCN 15535
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 . We thus conclude that this object is the
optical afterglow of GRB 131128A.

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

Using 1158 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 131128A, 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 = 355.30781, +31.30635 which is equivalent
to:

RA (J2000): 23h 41m 13.88s
Dec (J2000): +31d 18' 22.9"

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.

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
E. Sonbas (NASA/GSFC/Adiyaman Univ.), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 131128A (trigger #579683)
(Sonbas, et al., GCN Circ. 15533
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 ).  The BAT ground-calculated position is
RA, Dec = 355.305, 31.293 deg which is 
   RA(J2000)  =  23h 41m 13.3s 
   Dec(J2000) = +31d 17' 34.1" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 41%.
 
The mask-weighted light curve shows a single symetric peak starting 
at ~T-2 sec, peaking at ~T+0.2 src, and ending at ~T+2.5 sec.
T90 (15-350 keV) is 3.00 +- 1.41 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.90 to T+2.10 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.81 +- 0.17.  The fluence in the 15-150 keV band is 3.2 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.10 sec in the 15-150 keV band
is 2.7 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/579683/BA/

E. Sonbas (Adiyaman Univ.), T. Guver (Sabanci Univ.), E. Gogus (Sabanci
Univ.),
O. Erece (Akdeniz Univ), M. Kocak (TUG), M. Kaplan (Akdeniz Univ.) report
on behalf of a larger collaboration

    We observed the field of Swift GRB 131128A (Sonbas et al., GCN#15533
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 )
with the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National
Observatory, Turkey), starting November, 28, 17:16:02 UT (~ 2.2 hours after
the trigger). 300 s $\times$ 5  exposures were obtained in the R filter
under moderate weather conditions.

We do not detect an optical  afterglow within the reported XRT error circle
down to  a limiting magnitude of 21.2 in the  R band. Our image is
calibrated  using USNO B1.0  star USNO-B1 1213-0590145 at  RA :355.25992,
DEC : +31.301542 (J2000).

We are grateful to TUBITAK National Observatory for prompt scheduling the
observations and technical support.

K. S. Kawabata, R. Itoh, N. Ebisuda, I. Ueno (Hiroshima Univ.) 
report on behalf of Kanata team:

We performed a series of optical imaging (polarimetric mode) for 
the optical afterglow of GRB 131128A (Sonbas et al., GCN 15533
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 ; 
Xu et al., GCN 15535
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 ; Gorbovskoy et al, GCN 15536
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 ; Goad et al., 
GCN 15538
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 ; Sonbas et al., GCN 15540
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 ) using HOWPol attached to 
the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Japan. 

Our first 30 sec exposure began at t=360 sec since Swift/BAT trigger
and we detected the afterglow located at 9" west and 4" north of the 
bright star, USNO-B 2766-00858-1 (R2 = 11.63 mag). The magnitude of 
the afterglow is preliminarily estimated to be about R=17.5, although 
it might be still contaminated by the neaby bright star. The afterglow
quickly decayed and became fainter than ~18 mag at t=620 sec.

P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), A. Melandri
(INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), P. D'Avanzo (INAF-OAB), D.N.
Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U.
Leicester) and E. Sonbas report on behalf of the Swift-XRT team:

We have analysed 7.6 ks of XRT data for GRB 131128A (Sonbas  et al. GCN
Circ. 15533
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 ),  from 72 s to 40.8 ks after the  BAT trigger. The data
comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Goad et al. (GCN. Circ 15538).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.9 (+/-0.4). At T+423 s  the decay
flattens to an alpha of 0.38 (+0.08, -0.14) before breaking again at
T+16.0 ks to a final decay with index alpha=1.7 (+0.7, -0.6).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.53 (+0.18, -0.12). The
best-fitting absorption column is  5.8 (+4.6, -0.7) x 10^20 cm^-2,
consistent with the Galactic value of 5.2 x 10^20 cm^-2 (Kalberla et
al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 4.6 x 10^-11 (5.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     5.8 (+4.6, -0.7) x 10^20 cm^-2
Galactic foreground: 5.2 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.53 (+0.18, -0.12)

If the light curve continues to decay with a power-law decay index of
1.7, the count rate at T+24 hours will be 3.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-13 (1.9 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00579683.

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

D. Kawamura, T. Sakamoto, I. Takahashi, S. Sugai, A. Yoshida (AGU)

We observed the field of GRB 131128A detected by Swift (trigger #579683; 
Sonbas et al., GCN Circ. 15533
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 ) with the 12-inch AGU Robotic Optical 
Monitor for Astrophysical object - Narrow (AROMA-N) located at the Sagamihara 
campus of Aoyama Gakuin University.  

60 images of 10 sec exposures were taken in the R filter starting from 
November 28 15:12:47 (UT) about 383 sec after the trigger 
(77 sec after the BAT position notice) and stopped on November 28 15:30:30 (UT).  
We do not detect the optical afterglow both in the individual images and 
the stacked image inside the enhanced XRT position (Evans, et al., GCN #15538
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 ).  
The estimated five sigma upper limit of the combined image (total exposure of  600 sec) 
is ~16.2 mag using the USNO-B1 catalog.

S. R. Oates (UCL-MSSL) and E. Sonbas (NASA/GSFC/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131128A
91 s after the BAT trigger (Sonbas et al., GCN Circ. 15533
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 ).
A source consistent with the optical position (Xu et al., GCN Circ. 15535
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 ) 
and the enhanced Swift-XRT position (Goad et al., GCN Circ 15538
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 ) is 
detected in the first UVOT white exposure only. A USNO-B1 catalogued star 
heavily contaminates the position of the optical candidate afterglow 
making the measurement very complicated.

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

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

white (FC)          91          241           147        19.11 +/- 0.11
white		    583         1181          206    	 >21.44
u (FC)              303         552           245        >20.2
u                   303	        1130          285    	 >20.3
v                   632	        1231          78         >19.0
b                   558         1155          58         >19.8
w1                  683	        1275          53         >18.9
m2                  657         1255          78         >19.0
w2                  608	        1206          78         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst

S. Schmidl, S. Klose, A. Nicuesa Guelbenzu (TLS Tautenburg), and J. 
Greiner (MPE Garching) report:

We observed the field of GRB 131128A (Swift trigger 579683; Sonbas et al., 
GCN 15533
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 ) 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 00:27 UT on November 29, about 9.5 hrs after the 
GRB trigger and were performed under moderate seeing conditions (1.6") and 
moderate airmass (2.3). For the optical afterglow discovered by Xu et al. 
(GCN 15535
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 , 15537
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 ) we measure

RA, DEC (J2000) = 23:41:13.795, +31:18:22.32 (+/- 0.2"),

and

r'(AB) = 22.6 +/- 0.1,

calibrated against SDSS field stars (mean time 01:12 UT). Photometry in 
the other GROND bands is affected by a bright star very close to the 
afterglow. It might be improved once second-epoch data are obtained.

Subject: GRB 131128A: Fermi GBM observation

Hoi-Fung Yu (MPE) reports on behalf of the Fermi GBM Team:

"At 15:06:25.28 UT on 28 November 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131128A (trigger 407343988 / 131128629), which
was also detected by the Swift/BAT (Sonbas et al., GCN 15533
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 ). This burst,
tentatively classified as a particle event by the FSW onboard, is in fact
a gamma-ray burst. The GBM on-ground location is consistent with the 
Swift/XRT position.

The angle from the Fermi LAT boresight is 71 degrees.

The GBM light curve consists of a single pulse with a duration (T90) of 
~2.0 s (50-300 keV). The time-averaged spectrum from T0-1.024 s 
to T0+2.560 s is adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.9 +/- 0.3 and the cutoff 
energy, parameterized as Epeak, is 61.0 +/- 9.0 keV.

The event fluence (10-1000 keV) in this time interval is
(4.4 +/- 0.5)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.83 s in the 10-1000 keV band is 3.8 +/- 0.3 ph/s/cm^2.

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

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

We imaged the field of GRB 131128A detected 
by SWIFT(trigger 579683) with the robotic 
telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy (member of ISSP:Italian 
Supernovae Search Project)

The observations started 1h 28m after the                 
GRB trigger at the end of the twilight
with our schmidt telescope 
D=320/400 mm F/D=3.1.

Weather conditions were good.

We co-added 6 series of 10 exposures of 120 sec each.

We did not found any optical counterpart 
in the error box of the XRTcandidate
(E.Sonbas et al. GCNC 15533).

Start      End       Vlim
88min     279min     19.3                                   

The afterglow probably results absorbed in the light of 
the near star USNO-B 2766-00858-1 (R2 = 11.63 mag)   
due to the focal lenght very short (1000mm) of our 
Schmidt telescope.

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

The images are available at:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.