TITLE: GCN CIRCULAR NUMBER: 6247 SUBJECT: GRB 070406: Swift detection of a burst DATE: 07/04/06 21:00:11 GMT FROM: David Palmer at LANL J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), W. B. Landsman (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU) and E. Troja (INAF-IASFPA) report on behalf of the Swift Team: At 00:50:40 UT, BAT triggered and located GRB 070406 (Trigger #274153) as a sub-threshold (6.4 sigma) peak in a 0.256 second image. Subsequent ground analysis optimized the detection to a confident 8.3 sigma, at the location: RA, dec 198.956, +16.529d (J2000), which is RA(J2000) +13h 15m 49s dec(J2000) +16d 31' 46" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The burst is ~0.7 seconds long with a double-peaked profile, with a peak count rate of 1200 counts/s. Because the burst was sub-threshold on-board, Swift did not automatically slew to the GRB location. However a Target Of Opportunity (ToO) observation is currently being prepared with a 60 kilosecond observation beginning ~2200 UT.