TITLE: GCN CIRCULAR NUMBER: 33451 SUBJECT: Trigger 1159327: Swift detection of SGR1806-20 DATE: 23/03/10 21:15:35 GMT FROM: David Palmer at LANL R. Brivio (INAF-OAB), M. Ferro (INAF-OAB), D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 21:00:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located a bright burst from the Soft Gamma Repeater SGR 1806-20 (trigger=1159327). Swift did not immediately slew to the source. The BAT on-board calculated location is RA, Dec 272.154, -20.416 which is RA(J2000) = 18h 08m 37s Dec(J2000) = -20d 24' 56" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike structure with a duration of about 0.6 sec. The peak count rate was ~170,000 counts/sec (15-350 keV), at ~0 sec after the trigger. XRT follow-up observations are planned.