{
  "bibcode": "2015GCN.18777....1B",
  "body": "S. D. Barthelmy (GSFC), V. D'Elia (ASDC), C. Gronwall (PSU),\nL. Izzo (URoma/ICRA), H. A. Krimm (CRESST/GSFC/USRA),\nA. Y. Lien (GSFC/UMBC) and T. Sakamoto (AGU) report on behalf of the\nSwift Team:\n\nAt 22:26:00 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated V 404 Cyg (trigger=668877).  Swift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 305.945, +33.850, which is \n   RA(J2000)  =  20h 23m 47s\n   Dec(J2000) = +33d 50' 59\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical with image triggers, there is nothing\nobvious in the real-time light curve. \n\nThe XRT began observing the field at 22:28:09.1 UT, 128.7 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nlocated at RA, Dec 306.01806, 33.86606 which is equivalent to:\n   RA(J2000)  = 20h 24m 04.33s\n   Dec(J2000) = +33d 51' 57.8\"\nwith an uncertainty of 3.8 arcseconds (radius, 90% containment). . This\nposition may be improved as more data are received; the latest position\nis available at http://www.swift.ac.uk/sper. This position is 3.1\narcseconds from a known X-ray source: 1SXPS J202404.2+335155. This\nsource is in the Swift XRT 1SXPS catalogue with a mean 0.3-10 keV\ncount-rate of 0.0183 +/- 0.0015 ct/sec; see\nhttp://www.swift.ac.uk/1SXPS/1SXPSJ202404.2%2B335155 for details of\nthese previous observations. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata does not constrain the column density. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 132 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 XRT error circle. The list of sources is typically\ncomplete to about 18 mag. No correction has been made for the large, but\nuncertain extinction expected.",
  "circularId": 18777,
  "createdOn": 1451515074000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "Trigger 668877: Swift detection of V 404 Cyg",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>"
}