{
  "bibcode": "2018GCN.23364....1M",
  "body": "F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC),\nA. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), J. A. Kennea (PSU),\nH. A. Krimm (NSF/USRA), S. J. LaPorte (PSU),\nM. J. Moss (George Washington University), K. L. Page (U Leicester),\nD. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the\nNeil Gehrels Swift Observatory Team:\n\nAt 17:30:13 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 181022A (trigger=868312).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 56.795, -29.332, which is \n   RA(J2000)  =  03h 47m 11s\n   Dec(J2000) = -29d 19' 55\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single peak\nwith a duration of about 10 sec.  The peak count rate\nwas ~800 counts/sec (15-350 keV), at ~3 sec after the trigger. \n\nThe XRT began observing the field at 17:31:49.9 UT, 96.8 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source with an enhanced position: RA, Dec 56.7920,\n-29.3797 which is equivalent to:\n   RA(J2000)  = 03h 47m 10.09s\n   Dec(J2000) = -29d 22' 46.8\"\nwith an uncertainty of 2.1 arcseconds (radius, 90% containment). This\nlocation is 171 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 (8.80 x\n10^19 cm^-2, Willingale et al. 2013), with an excess column of 4.1\n(+3.17/-2.70) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 250 seconds with the U filter starting 97\nseconds after the BAT trigger. No credible afterglow candidate has been found\nin the initial data products. The 2.7'x2.7' sub-image covers none of the XRT\nerror circle. The 8'x8' region for the list of sources generated on-board\ncovers 100% of the XRT error circle. The list of sources is typically complete\nto about 18.0 mag. No correction has been made for the expected extinction\ncorresponding to E(B-V) of 0.01. \n\nThis source lies within the current (Sector 4) field-of-view of TESS camera 2. \n\nBurst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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/too.html.)",
  "circularId": 23364,
  "createdOn": 1540230812000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 181022A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 181022A"
}