GRB 121108A

T. N. Ukwatta (MSU), V. D'Elia (ASDC), H. A. Krimm (CRESST/GSFC/USRA),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU)
and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift
Team:

At 17:47:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 121108A (trigger=537921).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 83.186, +54.491 which is 
   RA(J2000) = 05h 32m 45s
   Dec(J2000) = +54d 29' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
peak structure for about 60 seconds, followed by an additional
peak at T+120 s.  The peak count rate was ~1500 counts/sec 
(15-350 keV), at ~28 sec after the trigger. 

The XRT began observing the field at 17:48:33.2 UT, 54.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 83.19368, 54.47191
which is equivalent to:
   RA(J2000)  = 05h 32m 46.48s
   Dec(J2000) = +54d 28' 18.9"
with an uncertainty of 4.3 arcseconds (radius, 90% containment). This
location is 70 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 1.87
x 10^21 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 1.96e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 63 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
0.37. 

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.)

Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 121108A detected by SWIFT
(trigger 537921) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 33.8s after the GRB trigger
(19.2s after the notice). The elevation of the field increased from
20 degrees above horizon and weather conditions
were good for the first images and became cloudy.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+33.8s to t0+93.8s : R > 15.8

The second image is 90.0s exposure in tracking mode:
t0+417.6s to t0+507.6s : R > 16.5

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

N.B. Galactic coordinates are lon=156.8411 lat=+11.3702
and the galactic extinction in R band is about 1.0 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

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

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

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

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

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

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

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


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB121108A (Ukwatta et. al. 
GCN13952
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 )  36 sec after notice  time and 54 sec after GRB time at 
2012-11-08 17:48:33.174 UT in two  polarizations. On our first (10s 
exposure) set we haven`t found optical transient  within SWIFT  error-box.
The 5-sigma upper limit has been about 15.8 mag
The message may be cited.

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

We observed the field of GRB 121108A (Ukwatta et al., GCN 13952
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 ) using
the 1m telescope located at Weihai, Shandong Province, China.
Observations started at 18:10 UT on 2012-11-08 (i.e., 22 mins after
the BAT trigger) and 4x600s exposures in the R filter were obtained.
No optical source was found within the enhanced XRT error circle down
to a limit of R~20.5 mag (3sigma), calibrated with the USNO B1
catalog.

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

We observed the field of GRB 121108A (Ukwatta et al., GCNC 13952)
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 2012-11-08 18:29:39 UT (~42 min after the
burst). We did not find any new point source within the XRT circle
(Ukwatta et al., GCNC 13952) 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
------------------------------------------------------
0.06526    19:21:37    5820.0   >22.6  >22.0  >20.0
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

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

Swift GRB 121108A (Ukwatta et al., GCN 13952
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 ) was observed with the 1.3m
Devasthal Fast Optical Telescope at Nainital. Three images in R_c pass-band
(300s each) were obtained starting at 2012-11-08 19:56:19 (UT).

In the co-added R_c frame (300s x 3), we did not detect any optical source
within the XRT error-box down to a limiting magnitude of ~21 mag.

This massage may be cited.

C.D. Lee, Y. Urata (NCU), K.Y. Huang (ASIAA)
on behalf of EAFON:

"We imaged the field of GRB 121108A (Ukwatta et al. GCN 13952
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 ) with
the Triple Range Imager and POLarimeter 2 (TRIPOL2) attached to the
Lulin 1m telescope. The simultaneous three color observations were
started on 2012-11-08 20:12:18.2 UT (~2.41 hrs after the burst).
There is no new sources in the error region of the X-ray afterglow
reported by Ukwatta et al. (GCN 13952
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 ) with three sigma limits of
g~20.6, r~20.5 and i~20.2 mag (at 2.92 hrs after the burst)."

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

Using 1705 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 121108A, 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 = 83.19408, +54.47352 which is equivalent
to:

RA (J2000): 05h 32m 46.58s
Dec (J2000): +54d 28' 24.7"

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.

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

We began to observe GRB121108A ( Ukwatta  et al., GCN 13952
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  ) 
with Xinglong TNT telescope at  17:49:47 (UT), about 128s after 
the burst.  A series of white and R-band images were obtained. 
No any optical counterpart was found in the X-ray errorbox 
(Beardmore et al., GCN 13959
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 ).  The 3 sigma upper limit is about 19.9 
mag in R-band calibrated by USNO B1.0 R2 mag,  at the mean 
time of 58 min after the burst. 

This message may be cited.

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

Using the data set from T-240 to T+962 sec from the recent
telemetry downlink, we report further analysis of BAT
GRB 121108A (trigger #537921) (Ukwatta, et al., GCN Circ. 13952
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 ).
The BAT ground-calculated position is RA, Dec = 83.216, 54.520 deg
which is
   RA(J2000)  =  05h 32m 51.9s
   Dec(J2000) = +54d 31' 11.2"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 90%.

BAT light curve shows two multi-peak episodes. First one starts
at the trigger time and lasts for about 50 seconds and the
second weak episode starts around T+130 seconds and lasts for about
40 seconds. T90 (15-350 keV) is 89 +- 48 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.15 to T+137.98 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 2.28 +- 0.20.  The fluence in the 15-150 keV band is
9.6 +- 1.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured
from T+43.18 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/537921/BA/

F. E. Marshall (NASA/GSFC) and T. N. Ukwatta (MSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 121108A
64 s after the BAT trigger (Ukwatta et al., GCN Circ. 13952
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 ).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 13959
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 )
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            64          213          147         >20.9
u_FC               276          526          246         >20.5
white               64         1721          412         >21.3
v                  605         1771          136         >19.6
b                  531         1697          117         >19.9
u                  276         1672          362         >20.6
w1                 655         1814          129         >19.6
m2                1429         1623           39         >19.6
w2                 581         1747          136         >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.37 in the direction of the burst
(Schlegel et al. 1998).

A. Melandri (INAF-OAB) and T. N. Ukwatta (MSU) report on behalf of the
Swift-XRT team:

We have analysed 24 ks of XRT data for GRB 121108A (Ukwatta  et al. GCN
Circ. 13952
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 ), from 47 s to 82.6 ks after the  BAT trigger. The data
comprise 129 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 13959).

The light curve (from T0+0.8 ks) can be modelled with a power-law decay
with a decay index of alpha=1.0 (+/-0.1). Flare activity is detected
from T0+100 and T0+200 s after the burst event.

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.60 (+/-0.09). The
best-fitting absorption column is  3.6 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.9 x 10^21 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.70 (+0.20, -0.18)
and a best-fitting absorption column of 2.3 (+0.7, -0.4) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.6 x 10^-11 (6.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.3 (+0.7, -0.4) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.70 (+0.20, -0.18)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00537921.

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

V. Rumyantsev, N.Pit' (CrAO), ��. Volnova (SAI MSU, IKI), A. Pozanenko 
(IKI) report on behalf of  larger GRB  follow-up collaboration:

We observed the field of  the Swift GRB 121108A (Ukwatta et al., GCN 
13952
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 ) with  AZT-11 telescope of CrAO observatory  starting on  Nov. 08 
(UT) 18:07:04. We took  several images in R-filter of 180 s exposure. 
Within enhanced XRT afterglow position (Beardmore et al., GCN 13959
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 ) we 
do not detect any new object.   A photometry of co-added frame is based 
  on the USNO-B1.0 (R2)  nearby  stars is following:

T0+,        Filter   Exposure,   OT,         UL (3 sigma)
mid, d                 (s)

0.02395     R        10x180      n/d         18.9