{
  "bibcode": "2005GCN..3382....1R",
  "body": "E.S. Rykoff (U Mich), H. Swan (U Mich), B. Schaefer (Louisiana State),\nR. Quimby (U Texas), report on behalf of the ROTSE collaboration:\n\nROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB\n050509B (Swift trigger 118749), producing images beginning 10.0 s after\nthe GCN notice time. An automated response took the first image at\n04:00:43.0 UT, 23.7 s after the burst, under excellent conditions. We\ntook 10 5-sec, 10 20-sec and 60+ 60-sec eposures. These unfiltered\nimages are calibrated relative to USNO A2.0 (R).  Imaging is ongoing.\n\nComparison to the DSS (second epoch) reveals no new sources within the\n3-sigma error circle, nor do we detect the tentative UVOT source\n(Hurkett et al, GCN 3381). Individual images have limiting magnitudes\nranging from 17.07-18.48. In particular, we set a limit of magnitude\n17.25 in a single 5 s exposure, starting 23.7 s after the burst.\nCoadding the images into sets of 10 reveals no new sources down to\nlimits of 18.63 (77 s effective length (t_end - t_start), beginning \n23.7s post-burst), 18.72 (298.5s effective length, beginning 100.6s \npost-burst), and 19.46 (695.6s effective length, beginning 399.1s \npost-burst).\n\n[GCN OPS NOTE (09may05):  Per author's request, the two references to 050509A\nwere changed to the correct value of 050509B.]",
  "circularId": 3382,
  "createdOn": 1115618423000,
  "email": "erykoff@umich.edu",
  "subject": "GRB 050509B: ROTSE-III Optical Limits",
  "submitter": "Eli Rykoff at U of Michigan/ROTSE  <erykoff@umich.edu>",
  "eventId": "GRB 050509B"
}