{
  "bibcode": "2009GCN..9914....1B",
  "body": "A. P. Beardmore, K. L. Page (U. Leicester) and T. Sakamoto (NASA/UMBC)\nreport on behalf of the Swift-XRT team :\n\nThe Swift-XRT started observing the field of GRB 090915 (Cummings and\nMarkwardt, GCN Circ. 9912) at 2009-09-16 03:59 UT, 12.4 hours after\nthe trigger. In 5ks of photon counting mode data, spanning two orbits,\nwe detect a source which fades from 0.0099 +/- 0.0022 count/s to\n0.0033 +/- 0.0016 over a interval of 5.9ks.\n\nUsing 1678 s of XRT Photon Counting mode data and 1 UVOT image, \nwe find an astrometrically corrected X-ray position (using the\nXRT-UVOT alignment and matching UVOT field sources to the USNO-B1\ncatalogue) for the source of RA, Dec (J2000) = 238.02021, 15.48775\nwhich is equivalent to :\n\nRA  (J2000):  15 52 4.85\nDec (J2000): +15 29 15.9\n\nwith an uncertainty of 3.3 arcsec (radius, 90% confidence).\n\nThis position may be improved as more data are received.  The latest\nposition can be viewed at http://www.swift.ac.uk/xrt_positions. Position\nenhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans\net al. (2009, MNRAS, 397, 1177).\n\nThe spectrum of the data from 44.6 ks to 52.8 ks after the trigger can\nbe fit by an absorbed powerlaw with a photon index of 1.20 +0.97/-0.54 \nand a column density upper limit of 1.4 x 10^21 cm^-2, consistent with\nthe Galactic value of 3.2 x 10^20 cm^-2 in the direction of the\nburst. The observed 0.3-10 keV flux for this spectrum is 4.9 +3.3/-4.9\nx 10^-13 erg cm^-2 s^-1 which corresponds to an unabsorbed 0.3-10 keV\nflux of 5.1 x 10^-13 erg cm^-2 s^-1.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9914,
  "createdOn": 1253099998000,
  "email": "apb@star.le.ac.uk",
  "subject": "GRB 090915: Swift-XRT detection of a fading X-ray counterpart",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 090915"
}