{
  "bibcode": "2014GCN.15765....1B",
  "body": "M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC),\nP. A. Evans (U Leicester), J. A. Kennea (PSU),\nA. Y. Lien (NASA/GSFC/ORAU), F. E. Marshall (NASA/GSFC),\nA. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL),\nM. H. Siegel (PSU) and C. A. Swenson (PSU) report on behalf of the\nSwift Team:\n\nAt 12:51:09 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 140129B (trigger=585149).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 326.763, +26.207 which is \n   RA(J2000) = 21h 47m 03s\n   Dec(J2000) = +26d 12' 24\"\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 2 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 12:52:16.5 UT, 67.1 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 326.7574, 26.2065 which\nis equivalent to:\n   RA(J2000)  = 21h 47m 01.77s\n   Dec(J2000) = +26d 12' 23.3\"\nwith an uncertainty of 2.1 arcseconds (radius, 90% containment). This\nlocation is 18 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 (5.58 x\n10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.7\n(+2.52/-2.09) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 356 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t21:47:01.67 = 326.75695\n  DEC(J2000) = +26:12:22.9  =  26.20637\nwith a 90%-confidence error radius of about 0.61 arc sec. This position is 1.5\narc sec. from the center of the XRT error circle. The estimated magnitude is\n16.92 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.09. \n\nBurst Advocate for this burst is M. G. Bernardini (grazia.bernardini AT brera.inaf.it). \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": 15765,
  "createdOn": 1391000838000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 140129B: Swift detection of a burst with an optical afterglow",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 140129B"
}