TITLE: GCN CIRCULAR NUMBER: 6511 SUBJECT: GRB 070612B: Swift detection of a burst DATE: 07/06/12 06:33:33 GMT FROM: Scott Barthelmy at NASA/GSFC D. Grupe (PSU), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU), W. B. Landsman (NASA/GSFC), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL), J. L. Racusin (PSU), P. Romano (Univ. Bicocca & INAF-OAB) and M. C. Stroh (PSU) report on behalf of the Swift Team: At 06:21:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070612B (trigger=282073). The BAT on-board calculated location is RA, Dec 261.713, -8.719 which is RA(J2000) = 17h 26m 51s Dec(J2000) = -08d 43' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showes a single peak with a duration of about 20 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. Because of an Earth limb constraint, the spacecraft did not slew promptly to the BAT position, and so there are no immediate XRT or UVOT data products to analyze. XRT and UVOT will begin observing this target at 07:13 UT.