TITLE: GCN CIRCULAR NUMBER: 6489 SUBJECT: GRB 070610: Swift detection of a burst DATE: 07/06/10 21:03:23 GMT FROM: Scott Barthelmy at NASA/GSFC C. Pagani (PSU), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Stamatikos (NASA/ORAU) and L. Vetere (PSU) report on behalf of the Swift Team: At 20:52:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070610 (trigger=281993). The BAT on-board calculated location is RA, Dec 298.795, +26.214 which is RA(J2000) = 19h 55m 11s Dec(J2000) = +26d 12' 49" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 10 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~3 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 21:42UT.