Status Report

GRB 051221: Swift detection of a bright short burst

By SpaceRef Editor
December 22, 2005
Filed under , ,
GRB 051221: Swift detection of a bright short burst

NUMBER: 4363
SUBJECT: GRB 051221: Swift detection of a bright short burst
DATE: 05/12/21 02:24:36 GMT
FROM: Scott Barthelmy at NASA/GSFC

A. Parsons (GSFC), S. Barthelmy (GSFC), D. Burrows (PSU), M. Capalbi (ASDC), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), C. Gronwall (PSU), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), F. Marshall (GSFC), K. Page (U Leicester), D. Palmer (LANL), on behalf of the Swift team:

At 01:51:16 UT, Swift-BAT triggered and located GRB 051221 (trigger=173780). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 328.711d,+16.896d {21h 54m 51s,+16d 53′ 45″} with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a single bright short peak at T0 with a duration less than 128 msec followed by a 2nd smaller and much softer peak at T+1 sec with an exponential decay lasting ~3 sec. The peak count rate was ~70,000 counts/sec (15-350 keV), at ~0 seconds after the trigger.

The XRT began observing the target at 01:52:44 UT, 88 sec after the burst. There was no source bright enough for an on-board centroid determination, but the TDRSS spectrum and lightcurve suggest the presence of an X-ray source in the field of view. Further analysis will require the full data dump through the Malindi ground station.

UVOT took a finding chart exposure of 199.9 seconds with the V filter starting 86.1 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7’x2.7′ sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit is about 18.7 mag. The 8’x8′ region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected visual extinction of about 0.23 magnitudes.

SpaceRef staff editor.