{
  "bibcode": "2020GCN.29158....1G",
  "body": "J.D. Gropp (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),\nN. J. Klingler (PSU), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU) and\nM. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 17:58:26 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 201223A (trigger=1014316).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 132.849, +71.174 which is \n   RA(J2000) = 08h 51m 24s\n   Dec(J2000) = +71d 10' 26\"\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 50 sec.  The peak count rate\nwas ~1600 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 17:59:40.7 UT, 73.7 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 132.78615, 71.17926 which\nis equivalent to:\n   RA(J2000)  = 08h 51m 08.68s\n   Dec(J2000) = +71d 10' 45.3\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 75 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 consistent with the Galactic value of 3.13\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 78 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t08:51:09.51 = 132.78963\n  DEC(J2000) = +71:10:47.4  =  71.17982\nwith a 90%-confidence error radius of about 0.61 arc sec. This position is 3.8\narc sec. from the center of the XRT error circle. The estimated magnitude is\n16.16 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.05. \n\nBurst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). \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": 29158,
  "createdOn": 1608747133000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 201223A: Swift detection of a burst with a bright optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 201223A"
}