TITLE: GCN CIRCULAR NUMBER: 14127 SUBJECT: GRB 130102A: Swift detection of a burst DATE: 13/01/02 18:27:44 GMT FROM: Scott Barthelmy at NASA/GSFC K. L. Page (U Leicester), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 18:10:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130102A (trigger=544784). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 311.464, +49.835 which is RA(J2000) = 20h 45m 51s Dec(J2000) = +49d 50' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As per usual for an image trigger, the TDRSS lightcurve does not show anything significant. The XRT began observing the field at 18:12:50.3 UT, 116.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 311.4233, 49.8174 which is equivalent to: RA(J2000) = 20h 45m 41.60s Dec(J2000) = +49d 49' 02.6" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 113 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 7.96 x 10^21 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 5.62e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 125 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected. We note that this event is at galactic coordinates: l = 88.33 deg, b = 4.22 deg. It has the characteristics of a GRB, but could be a galactic transient since it is close to the galactic plane. Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 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.)