{
  "bibcode": "2015GCN.17728....1P",
  "body": "C. Pagani (U Leicester), V. D'Elia (ASDC), K. L. Page (U Leicester),\nD. M. Palmer (LANL) and T. N. Ukwatta (LANL) report on behalf of the\nSwift Team:\n\nAt 06:28:04 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 150423A (trigger=638808). Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 221.600, +12.288 which is \n   RA(J2000) = 14h 46m 24s\n   Dec(J2000) = +12d 17' 18\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). The BAT light curve showed a single peak \nwith a duration of about 0.5 sec. The peak count rate was ~6400 \ncounts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 06:29:14.8 UT, 70.1 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 221.5787, 12.2833 which\nis equivalent to:\n   RA(J2000)  = 14h 46m 18.90s\n   Dec(J2000) = +12d 16' 60.0\"\nwith an uncertainty of 2.4 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.  We\ncannot determine whether the source is fading 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 1.77\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 73 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 29% 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 expected extinction corresponding to E(B-V) of\n0.03. \n\nBurst Advocate for this burst is C. Pagani (cp232 AT star.le.ac.uk). \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": 17728,
  "createdOn": 1429771378000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 150423A: Swift detection of a short burst",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 150423A"
}