BAT-Swift detection of a bright GRB

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 3839
SUBJECT: GRB050820B: BAT-Swift detection of a bright GRB
DATE: 05/08/21 00:23:42 GMT
FROM: David Palmer at LANL dmpalmer@mac.com

M. Page (UCL-MSSL), D. Palmer (LANL), S. Barthelmy (GSFC), D. Burrows (PSU), A. Beardmore (U. Leicester). J. Kennea (PSU), M. Chester (PSU), and T. Sakamoto (GSFC/NRC) on behalf of the Swift team report

At 23:50:27 BAT triggered and located GRB050820B (Trigger= 151334) at RA,Dec=135.557d, -72.668d {+09h 02m 14s, -72d 40′ 03″} (J2000) with an uncertainty of 2 arcmin (radius, 90% containment, stat+sys). The BAT lightcurve shows 20 seconds of emission with a shorter softer peak at T+2 seconds, and a broader, brighter, harder interval of emission from T+6 to T+14s. The peak count rate is 10,000 counts/s (15-350 keV) at T+9s. The first peak has a maximum count rate of 2000 counts/s, with no obvious emission above 100 keV.

Due to Earth limb constraints, the Swift slew is delayed until until 00:16 UT (T+26 minutes).