[vsnet-grb-info 2484] GRB 051210: BAT further refined analysis of the short burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4321
SUBJECT: GRB 051210: BAT further refined analysis of the short burst
DATE:    05/12/10 21:33:04 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), N. Gehrels (GSFC),
J. Norris (GSFC), D. Palmer (LANL), A. Parsons (GSFC)
on behalf of the Swift-BAT team:

The BAT team now believes this burst to be definitely short.  The formal
T90 value is 1.2 +/- 0.2 sec (Sato, Circ 4318).  The 6-sec_duration statement
in our 1st circ (Mangano, Circ 4315) was based on a non-background-subtracted
raw TDRSS lightcurve.  We now have the mask-tagged lightcurve with a
ground energy scale calibration applied to the events, and the 2nd peak
at T+6 sec is not present (it may be attributable to a background fluctuation or
noisy detector(s)).  We further note that the peak at T0 is resolved
into 3 separate peaks which is not uncommon in the BATSE short bursts.

The spectral lag (Norris & Bonnell, submitted to ApJ) for this burst
is -0.0010 sec (+0.0150 -0.0170 sec); very typical for short bursts.

Swift-XRT & UVOT follow-up observations are continuing and we encourage
other follow-up observations on this short burst.