{
  "bibcode": "2017GCN.21960....1C",
  "body": "S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB),\nJ. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU)\nand A. Tohuvavohu (PSU) report on behalf of the Swift Team:\n\nAt 02:37:00 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 171003A (trigger=775946).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 40.910, +61.408, which is \n   RA(J2000)  =  02h 43m 38s\n   Dec(J2000) = +61d 24' 28\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for image triggers, the real-time\nlight curve does not show anything significant. \n\nThe XRT began observing the field at 02:43:29.0 UT, 388.9 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 40.9186, 61.4323 which is equivalent to:\n   RA(J2000)  = +02h 43m 40.46s\n   Dec(J2000) = +61d 25' 56.3\"\nwith an uncertainty of 5.4 arcseconds (radius, 90% containment). This\nlocation is 88 arcseconds from the BAT onboard position, within the BAT\nerror circle. No event data are yet available to determine the column\ndensity using X-ray spectroscopy. \n\nThe initial flux in the 2.5 s image was 1.29e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White\nfilter  starting 400 seconds after the BAT trigger. No credible\nafterglow candidate has  been found in the initial data products. The\n2.7'x2.7' sub-image covers 100% of  the XRT error circle. The typical\n3-sigma upper limit has been about 19.6 mag.  The 8'x8' region for the\nlist of sources generated on-board covers 100% of the  XRT error\ncircle. The list of sources is typically complete to about 18 mag. No \ncorrection has been made for the large, but uncertain extinction\nexpected. The analysis is complicated by the proximity of a known star\nwith a USNO V magnitude of 12.01 approximately 7.7 arc-seconds from\nthe XRT position. \n\nBased on this source's proximity to the Galactic plane \n(latitude=1.4 degrees) and the duration of the BAT image trigger\n(>5 minutes), there is a possibility that this is a\nGalactic transient (i.e. Swift J0243.6+6124) rather than a GRB.  \nThe nature of this source will be determined by the full downloaded\ndataset and further observations. \n\nBurst Advocate for this burst is S. B. Cenko (brad.cenko 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/too.html.)",
  "circularId": 21960,
  "createdOn": 1507000958000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 171003A: Swift detection of a burst or a Galactic Transient",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 171003A"
}