TITLE: GCN CIRCULAR NUMBER: 5790 SUBJECT: GRB 061109: Swift detection of a possible burst DATE: 06/11/09 00:57:49 GMT FROM: Scott Barthelmy at NASA/GSFC A. D. Falcone (PSU), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC), K. M. McLean (LANL/UTD), C. Pagani (PSU), D. M. Palmer (LANL), G. Sato (GSFC/ISAS) and L. Vetere (PSU) report on behalf of the Swift Team: At 00:30:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located a possible GRB 061109 (trigger=237821). Swift slewed immediately to the location. The BAT on-board calculated location is RA,Dec 311.747, +24.166 {+20h 46m 59s, +24d 09' 59"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The XRT began taking data at 00:31:28 UT, 69 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image and no prompt position is available. The prompt lightcurve from XRT reveals no detectable emission. We are waiting for down-linked data to detect and determine if an afterglow is present. The usual UVOT data products (finding charts and source lists) will be available when the full data set is down and processed at ~02:15 UT. Due to a problem in the telemetry stream that started part way through the sequence of messages that come down TDRSS for each trigger, we do not have any BAT lightcurves, XRT images or any of the UVOT messages.