TITLE: GCN CIRCULAR NUMBER: 15157 SUBJECT: Swift Trigger 569022: a possible GRB DATE: 13/09/01 09:39:14 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), C. J. Mountford (U Leicester), M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 09:13:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 130901A or a Galactic source (trigger=569022). Swift slewed immediately to the detected source position. The BAT on-board calculated location is RA, Dec 263.611, -30.402 which is RA(J2000) = 17h 34m 27s Dec(J2000) = -30d 24' 07" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve does not show significant variation, which is not unusual for an image-based trigger. The XRT began observing the field at 09:15:20.0 UT, 123.0 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 263.6018, -30.3961 which is equivalent to: RA(J2000) = +17h 34m 24.43s Dec(J2000) = -30d 23' 46.0" with an uncertainty of 5.3 arcseconds (radius, 90% containment). This location is 35 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 0.1 s image was 3.68e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 4 seconds with the White filter starting 131 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image cover 100% of the XRT error circle. Results from the list of sources generated on-board are not available at this time. This burst occurred at Galactic coordinates l = 357.47, b = 1.29, that is only 2.8 deg away from the Galactic Center. At this stage, we cannot confirm whether this is a Galactic or extragalactic transient. Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 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.)