{
  "subject": "GRB 100117A: Swift detection of a short hard burst",
  "eventId": "GRB 100117A",
  "bibcode": "2010GCN.10336....1D",
  "createdOn": 1263763166000,
  "circularId": 10336,
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "email": "scott@lheamail.gsfc.nasa.gov",
  "body": "M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC),\nD. N. Burrows (PSU), S. Campana (INAF-OAB), P.A. Curran (MSSL-UCL),  \nN. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),\nV. Mangano (INAF-IASFPA), R. Margutti (Univ Bicocca&OAB),\nC. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC),\nC. Pagani (PSU), D. M. Palmer (LANL), P. Romano (INAF-IASFPA),\nT. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA),\nM. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and\nT. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:\n\nAt 21:06:19 UT, the Swift Burst Alert Telescope (BAT) triggered and  \nlocated GRB 100117A (trigger=382941).  Swift slewed immediately to the burst.\nThe BAT on-board calculated location is\nRA, Dec 11.260, -1.594 which is\n   RA(J2000)  =  00h 45m 02s\n   Dec(J2000) = -01d 35' 38\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including\nsystematic uncertainty).  The BAT light curve shows a single spike   \nstructure with a duration of about 0.4 sec.  The peak count rate\nwas ~4500 counts/sec (15-350 keV), at T_zero.\n\nThe XRT began observing the field at 21:07:39.6 UT, 80.1 seconds after   \nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 11.26946, -1.59620 which\nis equivalent to:\n   RA(J2000)  = 00h 45m 4.67s\n   Dec(J2000) = -01d 35' 46.3\"\nwith an uncertainty of 4.6 arcseconds (radius, 90% containment). This\nlocation is 34 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 (2.66e+20\ncm^-2, Kalberla et al. 2005), with an excess column of 4 (+3.65/-2.58)\nx 10^21 cm^-2 (90% confidence).\n\nThe initial flux in the 2.5 s image was 1.24e-09 erg cm^-2 s^-1 (0.2-10\nkeV).\n\n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 88 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 expected extinction corresponding to E(B-V) of\n0.02.\n\n\n\nBurst Advocate for this burst is M. De Pasquale (mdp AT mssl.ucl.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.)"
}