{
  "bibcode": "2010GCN.11277....1L",
  "body": "O. M. Littlejohns (U Leicester), S. D. Barthelmy (GSFC),\nD. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),\nN. Gehrels (NASA/GSFC), J. M. Gelbord (PSU),\nS. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),\nC. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), A. Rowlinson (U Leicester),\nM. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf\nof the Swift Team:\n\nAt 01:31:05 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100915A (trigger=434178).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is RA, Dec 315.648, +65.667 which is \n   RA(J2000) = 21h 02m 36s\n   Dec(J2000) = +65d 39' 60\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  This is a BAT image-only trigger with significance\nreported on-board of 8.67 sigma.  Ground processing of the BAT scaled map\nimage indicates a slightly weaker, 6.4 sigma excess.  As is typical for \nsuch triggers, there is nothing obvious in the raw light curve.  We will \nneed to wait for event-by-event data on the ground to clarify the nature \nof the light curve. \n\nThe XRT began observing the field at 01:33:17.7 UT, 131.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source with an enhanced position: RA, Dec\n315.6937, 65.6731 which is equivalent to:\n   RA(J2000)  = 21h 02m 46.50s\n   Dec(J2000) = +65d 40' 23.0\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 71 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 consistent with the Galactic value of 2.27\nx 10^21 cm^-2 (Kalberla et al. 2005). \n\nThe initial flux in the 2.5 s image was 5.89e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 140 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\n0.51. \n\nBurst Advocate for this burst is O. M. Littlejohns (oml2 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": 11277,
  "createdOn": 1284515502000,
  "email": "kennea@astro.psu.edu",
  "subject": "GRB 100915A: Swift detection of a likely burst",
  "submitter": "Jamie A. Kennea at PSU/Swift-XRT  <kennea@astro.psu.edu>",
  "eventId": "GRB 100915A"
}