{
  "bibcode": "2021GCN.30846....1T",
  "body": "A. Tohuvavohu (U Toronto), S. D. Barthelmy (GSFC),\nA. Y. Lien (U Tampa) and B. Sbarufatti (PSU) report on behalf of the\nNeil Gehrels Swift Observatory Team:\n\nAt 00:28:33 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a short GRB 210919A (trigger=1073893). Swift slewed immediately \nto the burst. The BAT on-board calculated location is \nRA, Dec 80.230, +1.274 which is \n   RA(J2000) = 05h 20m 55s\n   Dec(J2000) = +01d 16' 27\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 0.3 sec.  The peak count rate\nwas ~3500 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 00:30:10.5 UT, 97.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 80.25441, 1.31189 which is equivalent\nto:\n   RA(J2000)  = 05h 21m 01.06s\n   Dec(J2000) = +01d 18' 42.8\"\nwith an uncertainty of 6.9 arcseconds (radius, 90% containment). This\nlocation is 162 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttps://www.swift.ac.uk/sper.  We cannot determine whether the source\nis fading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 1.56\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 99 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers 100% of the XRT error circle. The list of sources is typically\ncomplete to about 18 mag. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.142. \n\nBurst Advocate for this burst is A. Tohuvavohu (tohuvavohu AT astro.utoronto.ca). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)",
  "circularId": 30846,
  "createdOn": 1632012858000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 210919A: Swift detection of a short burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 210919A"
}