TITLE: GCN CIRCULAR NUMBER: 10412 SUBJECT: GRB 100213B: Swift detection of a burst DATE: 10/02/13 23:12:15 GMT FROM: Scott Barthelmy at NASA/GSFC L. Vetere (PSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. M. Gelbord (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), M. H. Siegel (PSU), M. C. Stroh (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 22:58:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100213B (trigger=412220). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 124.338, +43.455 which is RA(J2000) = 08h 17m 21s Dec(J2000) = +43d 27' 19" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a FRED-like pulse structure with a duration of about 30 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 23:01:03.7 UT, 149.5 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 124.2858, +43.4473 which is equivalent to: RA(J2000) = 08h 17m 08.59s Dec(J2000) = +43d 26' 50.2" with an uncertainty of 5.2 arcseconds (radius, 90% containment). No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 1.75e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 77 seconds with the White filter starting 157 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 3-sigma upper limit is about 20.5 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 expected extinction corresponding to E(B-V) of 0.08. Burst Advocate for this burst is L. Vetere (vetere AT astro.psu.edu). 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.)