TITLE: GCN CIRCULAR NUMBER: 11553 SUBJECT: GRB 110112A: Swift detection of a possible short burst DATE: 11/01/12 04:26:58 GMT FROM: Michael Stamatikos at OSU/GSFC M. Stamatikos (OSU/NASA/GSFC), A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), O. M. Littlejohns (U Leicester), K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC), T. Sakamoto (NASA/UMBC), M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 04:12:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110112 A (trigger=442039). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 329.941, +26.489 which is RA(J2000) = 21h 59m 46s Dec(J2000) = +26d 29' 20" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 2 sec. The peak count rate was ~1700 counts/sec (15-350 keV), at the trigger time. The XRT began observing the field at 04:13:33.9 UT, 75.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 329.9330, 26.4564 which is equivalent to: RA(J2000) = 21h 59m 43.91s Dec(J2000) = +26d 27' 23.0" with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 119 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.54 x 10^20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 80 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The coverage of the XRT error circle by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. No correction has been made for the expected extinction corresponding to E(B-V) of 0.06. Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT 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.)