TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4315 SUBJECT: GRB 051210: Swift detection of a burst DATE: 05/12/10 06:26:53 GMT FROM: Scott Barthelmy at NASA/GSFC V. Mangano (INAF-IASS), S. Barthelmy (GSFC), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), S. Hunsberger (PSU), D. Palmer (LANL), A. Parsons (GSFC) on behalf of the Swift team: At 05:46:21 UT, Swift-BAT triggered and located GRB 051210 (trigger=171931). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 330.197d,-57.634d {22h 00m 47s,-57d 38' 01"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows two ~1-sec peaks with a total duration of ~6 sec. The peak count rate was ~2200 counts/sec (15-350 keV), at ~0 sec after the trigger. XRT began observing the field at 05:47:40.40, 79.2 sec after the BAT trigger. Onboard centroiding found a bright fading uncatalogued X-ray source in the field of view at the following coordinates: RA(J2000): 22h 00m 41.7s Dec(J2000): -57d 36' 48.2" We estimate the uncertainty of this position to be 6 arcsec (radius, 90% containment). This position is 84 arcsec from the BAT position above. The source initial flux is 9.7e-10 erg/cm2/sec. The UVOT data products were delayed and the results will be forthcoming in a second Circular.