{
  "bibcode": "2020GCN.28471....1M",
  "body": "M. J. Moss (GWU), E. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC),\nJ.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),\nF. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),\nD. M. Palmer (LANL), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report\non behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 12:06:46 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 200922A (trigger=997024).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 296.915, -55.204 which is \n   RA(J2000) = 19h 47m 40s\n   Dec(J2000) = -55d 12' 12\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single peak\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 12:08:02.2 UT, 75.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 296.95425, -55.20245 which\nis equivalent to:\n   RA(J2000)  = 19h 47m 49.02s\n   Dec(J2000) = -55d 12' 08.8\"\nwith an uncertainty of 4.2 arcseconds (radius, 90% containment). This\nlocation is 80 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at https://www.swift.ac.uk/sper.  We\ncannot determine whether the source is 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 4.71\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nThe initial flux in the 2.5 s image was 8.21e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White\nfilter  starting 85 seconds after the BAT trigger. The 2.7'x2.7'\nsub-image covers 100% of  the XRT error circle. There is a 14.4 mag\nsource at (296.95361,-55.20447)  8.3 arc seconds from the center of\nthe XRT error region. There is a  much weaker source at the same\nposition in the DSS. No  correction has been made for the expected\nextinction corresponding to E(B-V) of  0.05. \n\nBurst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). \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": 28471,
  "createdOn": 1600777584000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 200922A: Swift detection of a burst with possible optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 200922A"
}