GCN Circular 11509

S. R. Oates (UCL-MSSL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), V. D'Elia (ASDC),
N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), C. Gronwall (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
V. Mangano (INAF-IASFPA), C. B. Markwardt (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
C. J. Saxton (UCL-MSSL), B. Sbarufatti (INAF-OAB/IASFPA),
M. H. Siegel (PSU) and G. Stratta (ASDC) report on behalf of the Swift
Team:

At 18:52:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110102A (trigger=441454).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 245.879, +7.619 which is 
   RA(J2000)  =  16h 23m 31s
   Dec(J2000) = +07d 37' 09"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a weak precursor at T_zero
and then a bright FRED-like pulse at T+130 sec with a total duration
of about 170 sec.  The peak count rate was ~6000 counts/sec (15-350 keV),
at ~130 sec after the trigger. 

The XRT began observing the field at 18:54:54.0 UT, 148.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 245.8821, +7.6160 which is equivalent to:
   RA(J2000)  = 16h 23m 31.70s
   Dec(J2000) = +07d 36' 57.5"
with an uncertainty of 6.3 arcseconds (radius, 90% containment). This
location is 15 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 149 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	16:23:31.43 = 245.88096
  DEC(J2000) = +07:36:50.0  =	7.61390
with a 90%-confidence error radius of about 0.62 arc sec. This position is 8.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.93 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08. 

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