{
  "bibcode": "2018GCN.23309....1M",
  "body": "A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC),\nM. J. Moss (George Washington University), K. L. Page (U Leicester)\nand B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 05:55:51 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 181010A (trigger=866434).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 52.557, -23.035, which is \n   RA(J2000)  =  03h 30m 14s\n   Dec(J2000) = -23d 02' 06\"\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 25 sec.  The peak count rate\nwas ~2200 counts/sec (15-350 keV), at ~8 sec after the trigger. \n\nThe XRT began observing the field at 05:57:24.7 UT, 93.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 52.56984, -23.03721 which is equivalent\nto:\n   RA(J2000)  = 03h 30m 16.76s\n   Dec(J2000) = -23d 02' 14.0\"\nwith an uncertainty of 3.6 arcseconds (radius, 90% containment). This\nlocation is 43 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 (1.89 x\n10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.9\n(+2.46/-2.18) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 96 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t03:30:16.89 =  52.57036\n  DEC(J2000) = -23:02:15.4  = -23.03760\nwith a 90%-confidence error radius of about 0.78 arc sec. This position is 3.0\narc sec. from the center of the XRT error circle. The estimated magnitude is\n19.37 with a 1-sigma error of about  0.16. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.03. \n\nBurst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). \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/too.html.)",
  "circularId": 23309,
  "createdOn": 1539151652000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 181010A: Swift detection of a burst with an optical counterpart",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 181010A"
}