[vsnet-grb-info 12138] Trigger 529076: Swift possible detection of SwJ1910.2-0546

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13527
SUBJECT: Trigger 529076: Swift possible detection of SwJ1910.2-0546
DATE:    12/07/29 08:21:55 GMT
FROM:    Tilan Ukwatta at MSU  <tilan.ukwatta at gmail.com>

M. M. Chester (PSU), V. Mangano (INAF-IASFPA),
A. Maselli (INAF-IASFPA) and T. N. Ukwatta (MSU) report on behalf of
the Swift Team:

At 07:13:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a source (trigger=529076).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 287.652, -5.699 which is 
   RA(J2000) = 19h 10m 37s
   Dec(J2000) = -05d 41' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peak
structure with a duration of about 20 sec.  The peak count rate
was ~1464 counts/sec (15-350 keV), at ~11 sec after the trigger. 

The XRT began observing the field at 07:16:01.7 UT, 139.3 seconds after
the BAT trigger. XRT found a bright X-ray source located
at RA, Dec 287.5950, -5.8003 which is equivalent to:
   RA(J2000)  = +19h 10m 22.80s
   Dec(J2000) = -05d 48' 01.1"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 417 arcseconds from the BAT onboard position and 66 arcseconds 
from the known source SwJ1910.2-0546. As this position is significantly 
outside the BAT error circle, it is probably unrelated to the trigger. 
No event data are yet available to determine the column density using 
X-ray spectroscopy. 

The initial flux in the 2.5 s image was 6.25e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
306 seconds after the BAT trigger. There is a counterpart to the XRT source in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	19:10:22.80 = 287.59499
  DEC(J2000) = -05:47:55.8  =  -5.79884
with a 90%-confidence error radius of about 0.62 arc sec. This position is 4.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.17 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.61.