{
  "bibcode": "2015GCN.17377....1U",
  "body": "T. N. Ukwatta (LANL), W. H. Baumgartner (GSFC/UMBC),\nM. M. Chester (PSU), J. A. Kennea (PSU),\nH. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)\nreport on behalf of the Swift Team:\n\nAt 04:09:07 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 150203A (trigger=629578).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 98.415, +6.968 which is \n   RA(J2000) = 06h 33m 39s\n   Dec(J2000) = +06d 58' 04\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\nstructure with a duration of about 30 sec.  The peak count rate\nwas ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 04:10:21.5 UT, 74.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source with an enhanced position: RA, Dec\n98.3997, 6.9533 which is equivalent to:\n   RA(J2000)  = 06h 33m 35.92s\n   Dec(J2000) = +06d 57' 11.9\"\nwith an uncertainty of 2.3 arcseconds (radius, 90% containment). This\nlocation is 76 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 consistent with the Galactic value of 6.52\nx 10^21 cm^-2 (Willingale et al. 2013). \n\nThe initial flux in the 2.5 s image was 1.31e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 82 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 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the large, but uncertain extinction expected. \n\nBurst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). \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": 17377,
  "createdOn": 1422937420000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 150203A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 150203A"
}