{
  "bibcode": "2015GCN.17769....1P",
  "body": "D. A. Perley (Caltech) reports on behalf of a larger collaboration:\n\nWe observed the field of GRB 150428A (Page et al., GCN 17765) using the \nPalomar 60-inch robotic telescope starting at UT 03:40:50 on the night \nof 2015-04-28, acquiring a sequence of r, i, and z-band exposures under \nexcellent seeing conditions.\n\nStacking a series of 9x180s i-band images between 03:44 and 04:25 UT, we \ndetect no sources within the enhanced XRT error circle (Osborne et al., \nGCN 17768) down to a limiting magnitude of i > 22.7 mag at a median time \nof 2.65 hours after the trigger.  We note that the source reported by \nGROND (Knust et al., GCN 17767) is not within the enhanced error circle, \nbut we marginally detect this source at a similar magnitude (i = 22.8 \n+/- 0.3 mag).",
  "circularId": 17769,
  "createdOn": 1430200844000,
  "email": "dperley@astro.caltech.edu",
  "subject": "GRB 150428A: P60 observations",
  "submitter": "Daniel Perley at Caltech  <dperley@astro.caltech.edu>",
  "eventId": "GRB 150428A"
}