TITLE: GCN CIRCULAR NUMBER: 11461 SUBJECT: GRB 101219A: Swift detection of a short hard burst DATE: 10/12/19 02:50:58 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. M. Gelbord (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), D. Grupe (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 02:31:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 101219A (trigger=440606). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 74.616, -2.534 which is RA(J2000) = 04h 58m 28s Dec(J2000) = -02d 32' 01" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike with a duration of about 0.3 sec. The peak count rate was ~24000 counts/sec (15-350 keV), at 0.0 sec after the trigger. The XRT began observing the field at 02:32:30.0 UT, 60.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 74.5854, -2.5395 which is equivalent to: RA(J2000) = 04h 58m 20.49s Dec(J2000) = -02d 32' 22.4" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 111 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 in excess of the Galactic value (4.87 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.8 (+1.83/-1.57) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 278 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 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.06. Burst Advocate for this burst is J. M. Gelbord (jgelbord 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.)