[vsnet-grb-info 2032] GRB 050824: BAT refined analysis of a soft weak burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3871
SUBJECT: GRB 050824: BAT refined analysis of a soft weak burst
DATE:    05/08/25 04:40:32 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

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

Using the full data set from the recent telemetry downlink, we
report further analysis of Swift-BAT GRB 050824 (trigger #151905)
(Campana, et al., GCN 3866).  The ground-analysis position is
RA,Dec 12.256 +22.618 (J2000) with an uncertainty of 3 arcmin
(radius, 90%, stat+sys).  This is 1.9 arcmin from the onboard
position and 1.4 arcmin from the optical candidate reported by 
Gorosabel et al. in GCN Circ. 3865.

The light curve shows a single peak with slow rise and slow decay.  
T90 is 25 +- 5 seconds.  Fitting a simple power law over the 
interval from T+38 to T+64 sec, the photon index is 2.7 +/- 0.4 
with a fluence of 2.3 +/- 0.5 x 10^-7 erg/cm^2 in the 15-150 keV 
band (90% c.l).  The peak flux in a 1-second wide window starting 
at T+53 sec is 0.5 +/- 0.2 ph/cm^2/sec (15-150 keV). 

The original GCN Notices were delayed in transmission to the ground 
by 500 sec due to the burst happening during a telemetry downlink 
session when the TDRSS real-time messages are held in a buffer until 
the end of the downlink.