{
  "bibcode": "2021GCN.30160....1P",
  "body": "K. L. Page (U Leicester), M. A. Baer (PSU), J.D. Gropp (PSU),\nN. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 15:03:43 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 210610A (trigger=1054627).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 204.285, +14.480 which is \n   RA(J2000) = 13h 37m 08s\n   Dec(J2000) = +14d 28' 49\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\nstructure with a duration of about 15 sec.  The peak count rate\nwas ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 15:05:13.3 UT, 90.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 204.2823, 14.4652 which\nis equivalent to:\n   RA(J2000)  = 13h 37m 07.76s\n   Dec(J2000) = +14d 27' 54.7\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 54 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. No\nspectrum from the promptly downlinked event data is yet available to\ndetermine the column density. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 93 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t13:37:07.62 = 204.28174\n  DEC(J2000) = +14:27:55.0  =  14.46528\nwith a 90%-confidence error radius of about 0.61 arc sec. This position is 2.2\narc sec. from the center of the XRT error circle. The estimated magnitude is\n17.12 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.032. \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": 30160,
  "createdOn": 1623338804000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 210610A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 210610A"
}