{
  "bibcode": "2014GCN.16709....1V",
  "body": "A. Vargas (PSU), D. N. Burrows (PSU), S. B. Cenko (GSFC),\nN. Gehrels (NASA/GSFC), C. Gronwall (PSU), L. M. Z. Hagen (PSU),\nJ. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), J. L. Racusin (NASA/GSFC),\nB. Sbarufatti (INAF-OAB/PSU) and C. A. Swenson (PSU) report on behalf\nof the Swift Team:\n\nAt 18:44:16 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 140818B (trigger=609885).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 271.148, -1.361 which is \n   RA(J2000) = 18h 04m 35s\n   Dec(J2000) = -01d 21' 40\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a multi-peaked\nstructure with a duration of about 20 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 18:46:05.6 UT, 109.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 271.13656, -1.38660 which is equivalent\nto:\n   RA(J2000)  = 18h 04m 32.77s\n   Dec(J2000) = -01d 23' 11.8\"\nwith an uncertainty of 3.9 arcseconds (radius, 90% containment). This\nlocation is 100 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.  We cannot determine whether the source is\nfading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 3.53\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 113 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers 100% of the BAT error circle. Because of the density of\ncatalogued stars, further analysis is required to report an upper limit for any\nafterglow in the region. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.71. \n\nBurst Advocate for this burst is A. Vargas (avargas AT swift.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/too.html.)",
  "circularId": 16709,
  "createdOn": 1408388322000,
  "email": "burrows@astro.psu.edu",
  "subject": "GRB 140818B: Swift detection of a burst",
  "submitter": "David Burrows at PSU/Swift  <burrows@astro.psu.edu>",
  "eventId": "GRB 140818B"
}