TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5591 SUBJECT: GRB 060923C: Swift detection of a burst DATE: 06/09/23 13:48:45 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. Capalbi (ASDC), M.L. Conciatore (ASDC), C. Guidorzi (Univ Bicocca&INAF-OAB), S. T. Holland (GSFC/USRA), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/ORAU), D. E. Vanden Berk (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 13:33:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060923C (trigger=230711). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 346.127, +3.942 {23h 04m 30s, +03d 56' 32"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an image-trigger (88 sec), and as such, the BAT TDRSS lightcurve does not show significant activity. The XRT began observing the field at 13:36:25 UT, 203 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA(J2000) = 23h 04m 28.1s, Dec(J2000) = +03d 55' 30.3", with an estimated uncertainty of 8.1 arcseconds (90% confidence radius). This location is 70 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 8.5e-10 erg/cm2/s (0.2-10 keV). There is a 4th magnitude star 12 arcmin from the XRT error circle. Therefore, UVOT will not and can not observe this burst.