TITLE: GCN CIRCULAR NUMBER: 8804 SUBJECT: GRB 090113: Swift detection of a burst DATE: 09/01/13 19:06:45 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), A. M. Parsons (GSFC), B. A. Rowlinson (U Leicester), T. Sakamoto (NASA/UMBC), E. Troja (INAF-IASFPA), T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 18:40:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090113 (trigger=339852). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 32.073, +33.456 which is RA(J2000) = 02h 08m 18s Dec(J2000) = +33d 27' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows about 4 peaks with a duration of about 20 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 18:41:50.1 UT, 70.9 seconds after the BAT trigger. The onboard source-detection algorithm originally centroided on a hot column. No other source was visible in the initial TDRSS sub-image. We are waiting for the full Malindi dataset to detect and localise the afterglow. UVOT took a finding chart exposure of 150 seconds with the White filter starting 79 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The sub-image covers 25% of the BAT error circle. The overlap of the 8'x8' region for the list of sources generated on-board is 100% of the BAT error circle. This source list is usually complete to about 18th magnitude. No correction has been made for the expected extinction corresponding to E(B-V) of 0.08. This burst was also detected by Fermi-GBM. This burst is not to be confused with the BAT trigger (339853) about 12 minutes later on the 1A 1118-61 HMXB source. Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)