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 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.