GRB 191031C: Swift detection of a burst
Abstract
At 18:43:54 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191031C (trigger=932595). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 115.862, -62.335 which is RA(J2000) = 07h 43m 27s Dec(J2000) = -62d 20' 04" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 80 sec. The peak count rate was ~2400 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 18:45:16.2 UT, 81.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 115.8682, -62.3247 which is equivalent to: RA(J2000) = 07h 43m 28.37s Dec(J2000) = -62d 19' 28.9" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 38 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 2.5 s image was 2.60e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 90 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 expected extinction corresponding to E(B-V) of 0.17. Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it). 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/)
- Publication:
-
GRB Coordinates Network
- Pub Date:
- October 2019
- Bibcode:
- 2019GCN.26108....1A