{
  "bibcode": "2011GCN.12388....1P",
  "body": "D. A. Perley (Caltech), M. Ganeshalingam, P. Blanchard, and M. Mason (UC \nBerkeley) report:\n\nWe observed the location of bright IPN GRB 110918A (Hurley et al, GCN \n12357) starting at UT 2011-09-22 03:04:29 UT using the Nickel 40-inch \ntelescope at Lick Observatory, under good seeing conditions at high \nairmass.  A series of five 180-second exposures in R-band were acquired \nin total.  The optical afterglow (Tanvir et al., GCN 12365) is \nwell-detected in the combined stack.  Using five nearby USNOB1.0 stars, \nwe calculate the following photometry:\n\n   R = 20.68 +/- 0.13   (t_mid = 3.2406 day)\n\nThe uncertainty estimate does not include the uncertainty of the \ncalibration to USNO (for convenience, our calibration stars are listed \nbelow).  The measurement indicates a decay slope of approximately \nalpha=2.2 since the report of Guidorzi et al. (GCN 12382) and may \nsuggest a very early jet break for this burst (see also Cenko et al., \nGCN 12367).\n\nUSNO calibration stars:\nRA       \tdec       \tR2\n032.546809\t-27.104117\t19.38\n032.549492\t-27.121698\t19.29\n032.555214\t-27.117650\t19.38\n032.558045\t-27.100853\t19.39\n032.569403\t-27.106270\t19.40",
  "circularId": 12388,
  "createdOn": 1316741794000,
  "email": "dperley@astro.berkeley.edu",
  "subject": "GRB110918A: Lick Observations",
  "submitter": "Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>",
  "eventId": "GRB 110918A"
}