{
  "bibcode": "2015GCN.17707....1P",
  "body": "D. A. Perley (Caltech) and S. B. Cenko (GSFC) report:\n\nWe have continued to follow the optical counterpart of GRB 150413A \n(Markwardt et al., GCN 17688; Ivanov et al.,  GCN 17689) with the \nPalomar 60-inch robotic telescope.  A second griz epoch was acquired \nbetween 10:08:52 and 10:49:31 UT on the night of 2015-04-14, followed by \ntwo deeper epochs (one gri, one r only) on the night of UT 2015-04-15.\n\nCalibrating our r-band observations to a common set of USNO R-band \nreference stars, we derive the following photometry (statistical \nuncertainties only):\n\ndt_mid = 0.5602 day :  R = 19.13 +/- 0.03\ndt_mid = 0.8464 day :  R = 20.23 +/- 0.06\ndt_mid = 1.6034 day :  R = 21.52 +/- 0.16\ndt_mid = 1.8652 day :  R = 21.74 +/- 0.18\n\nThis suggests steep decay over this period (decay index ~ 2.2).",
  "circularId": 17707,
  "createdOn": 1429097390000,
  "email": "dperley@astro.caltech.edu",
  "subject": "GRB 150413A: additional P60 observations",
  "submitter": "Daniel Perley at Caltech  <dperley@astro.caltech.edu>",
  "eventId": "GRB 150413A"
}