{
  "bibcode": "2020GCN.27518....1S",
  "body": "K. K. Simpson (PSU), S. D. Barthelmy (GSFC), J.D. Gropp (PSU),\nJ. A. Kennea (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU)\nand A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels\nSwift Observatory Team:\n\nAt 02:25:10 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 200410A (trigger=965638).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 299.637, +51.763, which is \n   RA(J2000)  =  19h 58m 33s\n   Dec(J2000) = +51d 45' 48\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows multiple peaks\nwith a total duration of about 45 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 02:26:51.7 UT, 101.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source with an enhanced position: RA, Dec 299.6456,\n51.7813 which is equivalent to:\n   RA(J2000)  = 19h 58m 34.94s\n   Dec(J2000) = +51d 46' 52.5\"\nwith an uncertainty of 2.1 arcseconds (radius, 90% containment). This\nlocation is 68 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (2.15 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.3\n(+2.17/-1.95) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 104 seconds after the BAT trigger. There is a possible candidate\nafterglow in the rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t19:58:35.32 = 299.64717\n  DEC(J2000) = +51:46:53.0  = +51.78138\nwith a 90%-confidence error radius of about 0.6 arc sec. This position is 3.5\narc sec. from the center of the XRT error circle. The estimated magnitude is\n18.71 with a 1-sigma error of about  0.15. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.15. \n\nBurst Advocate for this burst is K. K. Simpson (kira.simpson1984 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": 27518,
  "createdOn": 1586486998000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 200410A: Swift detection of a burst with a possible optical counterpart",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 200410A"
}