TITLE: GCN CIRCULAR NUMBER: 8457 SUBJECT: Swift-BAT triggered on a probable GRB 081101 (trigger=333320) DATE: 08/11/01 12:21:04 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), N. P. M. Kuin (MSSL), V. La Parola (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL) and P. Romano (INAF-IASFPA) report on behalf of the Swift Team: At 11:46:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081101 (trigger=333320). Swift did not slew because of the low merit value assignment because of the chance spatial coincidence with the A0620-00 blackhole candidate source. The BAT on-board calculated location is RA, Dec 95.826, -0.082 which is RA(J2000) = 06h 23m 18s Dec(J2000) = -00d 04' 55" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single hard spike with a duration of less than 128 msec. The peak count rate was ~7000 counts/sec (15-350 keV), at ~0 sec after the trigger. We can not rule out that this was from A0620-00, although the position is a very unlikely 18 arcmin away. Thus, we believe this to be a gamma-ray burst, or possibly a new SGR (although the spectrum is harder than typical SGR bursts). Burst Advocate for this burst is M. Stamatikos (michael AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)