{
  "bibcode": "2020GCN.27591....1E",
  "body": "P. A. Evans (U Leicester), V. D'Elia (SSDC), J.D. Gropp (PSU),\nN. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST),\nA. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL)\nand A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels\nSwift Observatory Team:\n\nAt 07:05:17 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 200416A (trigger=966554).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 335.691, -7.530 which is \n   RA(J2000) = 22h 22m 46s\n   Dec(J2000) = -07d 31' 47\"\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 10 sec.  The peak count rate\nwas ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 07:06:57.1 UT, 99.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 335.69906, -7.51816 which\nis equivalent to:\n   RA(J2000)  = 22h 22m 47.77s\n   Dec(J2000) = -07d 31' 05.4\"\nwith an uncertainty of 3.5 arcseconds (radius, 90% containment). This\nlocation is 51 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 (6.54 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2\n(+3.00/-2.56) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 102 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t22:22:47.83 = 335.69929\n  DEC(J2000) = -07:31:05.9  =  -7.51831\nwith a 90%-confidence error radius of about 0.75 arc sec. This position is 1.1\narc sec. from the center of the XRT error circle. The estimated magnitude is\n16.47 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.06. \n\nBurst Advocate for this burst is P. A. Evans (pae9 AT star.le.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": 27591,
  "createdOn": 1587021576000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 200416A: Swift detection of a burst with an optical afterglow",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 200416A"
}