[vsnet-grb-info 4183] GRB 070103: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5988
SUBJECT: GRB 070103: Swift detection of a burst
DATE:    07/01/03 21:12:06 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

T. Sakamoto (NASA/ORAU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/GSFC/USRA),
S. Immler (GSFC/USRA), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
K. M. McLean (LANL/UTD), C. Pagani (PSU), S. B. Pandey (UCL-MSSL),
A. M. Parsons (GSFC), P. Romano (Univ. Bicocca & INAF-OAB),
B. Sbarufatti (INAF-IASFPA), D. E. Vanden Berk (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 20:46:39.41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB  (trigger=254532).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA=352.557, Dec=+26.875 (J2000),  which is 
   RA(J2000)  = 23h 30m 14s
   Dec(J2000) = +26d 52' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two peaks separated
by ~10 sec and a few more weak peaks extending out to ~T+20 sec. 
The peak count rate was ~2400 counts/sec (15-350 keV), at ~0 sec
after the trigger. 

The XRT began taking data at 20:47:48 UT, 69 seconds after the BAT
trigger.  The XRT on-board centroid algorithm did not find a source in the
image, however analysis of downlinked data reveals an uncatalogued point source 
at the position RA=352.5576, Dec=+26.8751 (J2000), which is
   RA(J2000)  = 23h 30m 13.82s
   Dec(J2000) = +26d 52' 30".21
with 4.74 arcsec error radius (90% containment). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 74 seconds after the BAT trigger, and a
400 second exposure with the V filter starting 179 seconds after the
trigger. No 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 3-sigma upper limit is 19.5 in white, 18.8 in V. No
correction has been made for the expected extinction corresponding to
E(B-V) of 0.07.