{
  "bibcode": "2021GCN.30700....1P",
  "body": "K. L. Page (U Leicester), N. J. Klingler (GSFC/UMBC/CRESSTII),\nH. A. Krimm (NSF), A. Y. Lien (U Tampa), M. H. Siegel (PSU) and\nA. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 04:10:01 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210824A (trigger=1070157).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 232.132, +11.135 which is \n   RA(J2000) = 15h 28m 32s\n   Dec(J2000) = +11d 08' 07\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a multi-peaked\nstructure with a duration of about 50 sec.  The peak count rate\nwas ~1600 counts/sec (15-350 keV), at ~3 sec after the trigger. \n\nThe XRT began observing the field at 04:15:08.4 UT, 306.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 232.10513, 11.15208 which\nis equivalent to:\n   RA(J2000)  = 15h 28m 25.23s\n   Dec(J2000) = +11d 09' 07.5\"\nwith an uncertainty of 7.2 arcseconds (radius, 90% containment). This\nlocation is 113 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (3.31 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 8.5\n(+5.30/-4.44) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 310 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 0.036. \n\nBurst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). \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": 30700,
  "createdOn": 1629779752000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 210824A: Swift detection of a burst",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 210824A"
}