{
  "bibcode": "2013GCN.14874....1R",
  "body": "J. L. Racusin (NASA/GSFC), J. R. Cummings (NASA/UMBC),\nN. Gehrels (NASA/GSFC), J. A. Kennea (PSU),\nC. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),\nC. Pagani (U Leicester), K. L. Page (U Leicester),\nD. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and\nM. H. Siegel (PSU) report on behalf of the Swift Team:\n\nAt 03:22:22 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 130612A (trigger=557976).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 259.804, +16.706 which is \n   RA(J2000) = 17h 19m 13s\n   Dec(J2000) = +16d 42' 21\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 5 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 03:23:49.1 UT, 87.0 seconds after\nthe BAT trigger. The position determined from promptly downlinked data\ndiffers significantly from the on-board position, suggesting that the\nXRT may have centroided on a cosmic ray; the initial XRT position\nnotice should be treated with caution. Using promptly downlinked data\nwe find an uncatalogued X-ray source with an enhanced position: RA, Dec\n259.7940, 16.7205 which is equivalent to:\n   RA(J2000)  = 17h 19m 10.55s\n   Dec(J2000) = +16d 43' 13.9\"\nwith an uncertainty of 2.7 arcseconds (radius, 90% containment). This\nlocation is 62 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 in excess of the Galactic value (5.96 x\n10^20 cm^-2, Kalberla et al. 2005), with an excess column of 7.8\n(+9.63/-6.58) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of  91 seconds with the White filter\nstarting 94 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t17:19:10.59 = 259.79411\n  DEC(J2000) = +16:43:11.7  =  16.71991\nwith a 90%-confidence error radius of about 0.64 arc sec. This position is 2.3\narc sec. from the center of the XRT error circle. The estimated magnitude is\n18.80 with a 1-sigma error of about  0.15. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.08. \n\nBurst Advocate for this burst is J. L. Racusin (judith.racusin 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": 14874,
  "createdOn": 1371008640000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 130612A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 130612A"
}