TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4717 SUBJECT: GRB 060209(?): Swift-BAT detection of a possible burst DATE: 06/02/09 19:44:31 GMT FROM: Scott Barthelmy at NASA/GSFC J. Osborne (U Leicester), S. Barthelmy (GSFC), N. Gehrels (GSFC), J. Kennea (PSU), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), F. Marshall (GSFC), K. Page (U Leicester), D. Palmer (LANL), T. Sakamoto (GSFC/ORAU), P. Schady (PSU/UCL-MSSL) on behalf of the Swift team: At 19:08:55 UT, Swift-BAT triggered and located GRB 060209 (trigger=180931). The spacecraft slewed immediately. The BAT on-board calculated location is RA,Dec 65.454,+58.730d {04h 21m 49s,+58d 43' 47"} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The TDRSS lightcurve does not show anything significant (in T-20 to T+128 sec) which is consistant with a weak short burst and with a cosmic ray shower. We will not be able to distinguish these until we get the full data in about an hour. The XRT began taking data at 19:10:00 UT, 64 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. We are waiting for down-linked data to detect and determine a position for the source. UVOT took a finding chart exposure of 200 seconds with the V filter starting 65 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 18th mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction of about 2.9 magnitudes.