GRB 051012: Swift-BAT detection of burst yesterday

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4093
SUBJECT: GRB 051012: Swift-BAT detection of burst yesterday
DATE: 05/10/13 22:15:40 GMT
FROM: Jay R. Cummings at NASA/GSFC/Swift jayc@milkyway.gsfc.nasa.gov

G. Sato (ISAS), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), D. Hinshaw (GSFC-SPSYS), H. Krimm (GSFC/USRA), K. McLean (LANL), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC), J. Tueller (GSFC), on behalf of the Swift-BAT team:

At 2005-10-12 17:05:58 UT, Swift-BAT triggered and detected GRB 051012 (trigger 159413). Because Swift was executing a preplanned slew, the burst was not identified onboard and no prompt notices were distributed. Using the data set from T-4 to T+16, the refined BAT ground position is RA, Dec 270.564d, -52.795d {18h 02m 15s, -52d 47′ 40″} [deg; J2000], +- 1.8 arcmin (radius, sys+stat, 90% containment). The burst was in the fully-coded field of view.

The lightcurve shows a single weak peak with a slow rise and fall from approximately T-3 to T+11 sec. T90 (15-350 keV) was 13 +- 1 sec (estimated error including systematics). Because of the slew, we cannot rule out further emission after T+16 sec.

The power law index of the time-averaged spectrum was 2.25 +- 0.25. The fluence in the 15-150 keV band was (2.9 +- 0.5) x 10^-7 ergs / cm^2. The 1-sec peak flux measured from T+3 sec in the 15-150 keV band was 0.6 +- 0.2 photons / cm^2 sec. All the quoted errors are at the 90% confidence level.