[AAVSO-HEN] GRB 080121: Swift-BAT detection of a very weak, short burst

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  7209
SUBJECT: GRB 080121: Swift-BAT detection of a very weak, short burst
DATE:    08/01/23 20:39:09 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

J. R. Cummings and D. M. Palmer for the Swift-BAT team

At 21:29:55 on Jan 21, 2008, BAT detected a weak short GRB 
(trigger #301491) at a ground-calculated location 
RA, Dec 137.235, +41.841, error radius 3 arcmin (90% confidence),
which is:
RA(J2000)  = 09h 08m 56s
Dec(J2000) = +41d 50' 29"
 
The significance of the source in the detection image was just 
below the alert threshold, so Swift did not slew immediately to 
the burst. In addition, the source location was in Moon constraint, 
so no late observation was made.

As seen in BAT, the burst was a single peak with T90 0.7 +- 0.2
seconds. Because of the weakness of the burst, a power-law fit to 
the spectrum from T-0.4 to T+0.4 sec is not well constrained. The 
power-law index is 2.6 +- 0.8. The fluence was 
(3 +- 2) x 10^-8 erg/cm2/sec. Quoted uncertainties are 90%
confidence including estimated systematic error.