{
  "bibcode": "2019GCN.23946....1T",
  "body": "E. Troja (NASA/GSFC/UMCP), S. D. Barthelmy (GSFC),\nA. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU),\nN. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC),\nM. J. Moss (George Washington University), K. L. Page (U Leicester)\nand M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 14:23:33 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 190311A (trigger=892607).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 212.102, +53.519 which is \n   RA(J2000) = 14h 08m 24s\n   Dec(J2000) = +53d 31' 10\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). From the available data, the BAT light curve showed \na single-peaked structure with duration of at least 10 sec. However, due to \na data gap from ~T+10 s to ~ T+ 110 s, there might be additional emission\nin that time interval. The peak count rate was ~1700 counts/sec (15-350 keV), \nat ~ 0 sec after the trigger. \n\nThe XRT began observing the field at 14:24:54.0 UT, 80.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source with an enhanced position: RA, Dec\n212.0649, 53.5007 which is equivalent to:\n   RA(J2000)  = 14h 08m 15.58s\n   Dec(J2000) = +53d 30' 02.7\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 103 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttp://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 (1.17 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.1\n(+3.27/-2.92) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 5.45e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 85 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t14:08:15.65 = 212.06522\n  DEC(J2000) = +53:30:03.0  =  53.50084\nwith a 90%-confidence error radius of about 0.60 arc sec. This position is 0.85\narc sec. from the center of the XRT error circle. The estimated magnitude is\n19.47 with a 1-sigma error of about  0.12. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.01. \n\nBurst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). \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": 23946,
  "createdOn": 1552315406000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 190311A: Swift detection of a burst with optical counterpart",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 190311A"
}