{
  "bibcode": "2019GCN.23908....1P",
  "body": "K. L. Page (U Leicester), N. J. Klingler (PSU),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU)\nand A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 02:59:34 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 190220A (trigger=889785).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 330.142, -76.691 which is \n   RA(J2000) = 22h 00m 34s\n   Dec(J2000) = -76d 41' 27\"\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 10 sec.  The peak count rate\nwas ~1700 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 03:00:55.5 UT, 80.8 seconds after\nthe BAT trigger. The position determined from promptly downlinked data\ndiffers significantly from the on-board position, suggesting that the\nXRT may have centroided on a cosmic ray; the initial XRT position\nnotice should be treated with caution. Using promptly downlinked data\nwe find an uncatalogued, fading X-ray source located at RA, Dec 330.16325,\n-76.68047 which is equivalent to:\n   RA(J2000)  = 22h 00m 39.18s\n   Dec(J2000) = -76d 40' 49.7\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 41 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 http://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 (1.10 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.9\n(+3.65/-3.07) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 86 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t22:00:39.14 = 330.16309\n  DEC(J2000) = -76:40:50.4  = -76.68067\nwith a 90%-confidence error radius of about 0.66 arc sec. This position is 3.1\narc sec. from the center of the XRT error circle. The estimated magnitude is\n19.29 with a 1-sigma error of about  0.16. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.13. \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": 23908,
  "createdOn": 1550632483000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 190220A: Swift detection of a burst with an optical counterpart",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 190220A"
}