Status Report

Swift-BAT detection of a possible burst

By SpaceRef Editor
December 22, 2005
Filed under , ,
Swift-BAT detection of a possible burst

NUMBER: 4376
SUBJECT: Swift-BAT detection of a possible burst
DATE: 05/12/21 20:51:54 GMT
FROM: Scott Barthelmy at NASA/GSFC

P. Boyd (GSFC), S. Barthelmy (GSFC), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), F. Marshall (GSFC), K. Page (U Leicester), D. Palmer (LANL), A. Parsons (GSFC), J. Racusin (PSU), P. Roming (PSU), T. Sakamoto (GSFC) on behalf of the Swift team:

At 20:03:20 UT, Swift-BAT triggered and located a source (trigger=173904). The spacecraft slewed promptly after the end of the image trigger. The BAT on-board calculated location is RA,Dec 312.395d,+53.054d {20h 49m 35s,+53d 03′ 14″} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). All we have at this time is the TDRSS lightcurve. This plus the fact that this is a 192-sec image trigger means that we can not say if this trigger is due to a real GRB, a hard x-ray transient, or a noise event. We note that the galactic latitude is 6 deg.

The XRT began observing the location at 20:07:56 UT, 276 sec after the BAT trigger. The on-board detection algorithm did not centroid on a source due to insufficient counts, so no prompt X-ray position is available. However, both the prompt XRT light-curve and raw spectrum indicate there is a faint X-ray source in the field. More information will be available after the next Malindi pass in a few hours.

UVOT took a finding chart exposure of 200 seconds with the V filter starting 275 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 has been about 18th 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 4.6 magnitudes.

SpaceRef staff editor.