TITLE: GCN CIRCULAR NUMBER: 12997 SUBJECT: GRB 120229A: Swift detection of a short burst DATE: 12/02/29 14:57:25 GMT FROM: David Palmer at LANL V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), B. Gendre (ASDC), C. Guidorzi (U Ferrara), S. T. Holland (STScI), J. A. Kennea (PSU), A. Y. Lien (NASA/GSFC/ORAU), O. M. Littlejohns (U Leicester), F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. T. O\'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), C. A. Swenson (PSU), G. Tagliaferri (INAF-OAB) and B.-B. Zhang (PSU) report on behalf of the Swift Team: At 14:35:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120229A (trigger=516571). Swift could not slew to the burst due to a sun constraint. The BAT on-board calculated location is RA, Dec 20.035, -35.807 which is RA(J2000) = 01h 20m 08s Dec(J2000) = -35d 48' 26" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single short peak structure with a duration of about 0.5 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 19:46 UT on 2012 April 17. There will thus be no XRT or UVOT data for this trigger before this time. We note that this location is 5 arc minutes from the relatively nearby (z=0.03) galaxy 6dFGSgJ012000.6-355307 . Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 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.)