TITLE: GCN CIRCULAR NUMBER: 26177 SUBJECT: GRB 191106A: Swift detection of a burst DATE: 19/11/06 14:27:48 GMT FROM: Scott Barthelmy at NASA/GSFC F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), M. G. Bernardini (INAF-OAB), D. N. Burrows (PSU), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), P. A. Evans (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), S. J. LaPorte (PSU), A. Melandri (INAF-OAB), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 14:15:23 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191106A (trigger=933515). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 269.350, +46.052, which is RA(J2000)c = 17h 57m 24s Dec(J2000) = +46d 03' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few peaks with a total duration of about 5 sec. The peak count rate was ~2800 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 14:16:34.2 UT, 70.3 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 269.3349, 46.0346 which is equivalent to: RA(J2000) = 17h 57m 20.38s Dec(J2000) = +46d 02' 04.7" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 73 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 (4.38 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4 (+4.05/-3.32) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 130 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.06. Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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/)