{
  "bibcode": "2021GCN.30677....1P",
  "body": "K. L. Page (U Leicester), J.D. Gropp (PSU), N. P. M. Kuin (UCL-MSSL)\nand A. Y. Lien (U Tampa) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 09:18:18 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210822A (trigger=1069788).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 304.476, +5.265 which is \n   RA(J2000) = 20h 17m 54s\n   Dec(J2000) = +05d 15' 54\"\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 30 sec.  The peak count rate\nwas ~38000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 09:19:32.7 UT, 74.6 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 304.4377, 5.2786 which is equivalent to:\n   RA(J2000)  = 20h 17m 45.05s\n   Dec(J2000) = +05d 16' 43.0\"\nwith an uncertainty of 11.9 arcseconds (radius, 90% containment). This\nlocation is 145 arcseconds from the BAT onboard position, within the\nBAT error circle. No event data are yet available to determine the\ncolumn density using X-ray spectroscopy. \n\nThe initial flux in the 0.1 s image was 1.25e-08 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 250 seconds with the U filter  \nstarting 297 seconds after the BAT trigger. An afterglow   candidate\nhas been found in the initial data products with a magnitude \n of u = 13.81 +/- 0.03. No correction  has been made for the expected \nextinction corresponding to E(B-V) of  0.162.   The preliminary UVOT \nposition is RA=304.43748, Dec = 5.28337 (J2000),  which is equivalent \nto:   \n   RA = 20h 17m 45.0s,  \n   Dec = +05d 17m 00.1s (J2000)    with an  uncertainty of about an\narcsecond. \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": 30677,
  "createdOn": 1629625933000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 210822A: Swift detection of a burst with an optical afterglow",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 210822A"
}