{
  "bibcode": "2012GCN.13875....1G",
  "body": "D. Grupe (PSU), B. N. Barlow (PSU), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),\nJ. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),\nE. A. Helder (PSU), S. T. Holland (STScI), J. A. Kennea (PSU),\nH. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC),\nF. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),\nK. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and\nC. A. Swenson (PSU) report on behalf of the Swift Team:\n\nAt 19:23:28 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 121017A (trigger=536172).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 288.816, -1.595 which is \n   RA(J2000)  =  19h 15m 16s\n   Dec(J2000) = -01d 35' 43\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows at least two peaks \nwith a duration of about 10 sec (possibly longer).  The peak count rate \nwas ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 19:25:03.3 UT, 95.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 288.8302, -1.6042 which\nis equivalent to:\n   RA(J2000)  = 19h 15m 19.25s\n   Dec(J2000) = -01d 36' 15.1\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 60 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 in excess of the Galactic value (2.22 x\n10^21 cm^-2, Kalberla et al. 2005), with an excess column of 3\n(+2.89/-2.40) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 1141 seconds after the BAT trigger. No credible afterglow candidate\nhas been found in the initial data products. The 2.7'x2.7' sub-image covers\n100% of the XRT error circle. There is no new source down to a limit of\nabout 19th mag. The 8'x8' region for the list of sources generated on-board covers\n100% of the XRT error circle. Because of the density of catalogued stars,\nfurther analysis is required to report an upper limit for any afterglow in the\nregion. No correction has been made for the expected extinction corresponding\nto E(B-V) of 0.44. \n\nXRT and UVOT detections were delayed due to entry into the SAA shortly\nafter the initial trigger. \n\nBurst Advocate for this burst is D. Grupe (grupe AT astro.psu.edu). \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": 13875,
  "createdOn": 1350503710000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 121017A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 121017A"
}