TITLE: GCN CIRCULAR NUMBER: 5654 SUBJECT: GRB 060929: Swift detection of a burst DATE: 06/09/29 20:36:10 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), S. D. Hunsberger (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB), T. Sakamoto (NASA/ORAU), G. Sato (GSFC/ISAS), P. Schady (MSSL-UCL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 19:55:01UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060929 (trigger=231702). Swift slewed immediately to the burst. The on-board location (obtained from a Lightcurve SERS message) is RA,Dec (J2000) 263.164,+29.815 {17h32m39s, 29d48m54s}. Because of a telemetry gap covering the first ~50 sec of the TDRSS messages, we can say nothing about the lightcurve until the full data set is downlinked. The XRT began taking data at 19:56:33 UT, 92 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image, however analysis of prompt downlinked data reveals a faint, uncatalogued point source at the following location: RA(J2000) = 17h 32m 29.0s Dec(J2000) = +29d 50m 08.5s with an estimated uncertainty of 7.3 arcseconds radius (90% containment). This source lies 154 arcseconds from the BAT position. At this time due to the telemetry gap, only a raw UVOT finding chart image (no sky coordinates) obtained with the white light filter is available. We have attempted to perform pattern matching with the DSS and no obvious afterglow candidate is seen.