{
  "bibcode": "2014GCN.16863....1F",
  "body": "W. Fong (U. Arizona), M. Calkins (SAO), and E. Berger (Harvard) report:\n\n\"We observed the location of the short-duration GRB 140930B (De Pasquale et\nal., GCN 16857) with MMTCam mounted on the 6.5-m MMT starting on 2014 Oct\n1.144 UT (7.76 hr post-burst). We obtained 4x300-sec of r-band observations\nin 1\" seeing. We detect a source at the position of the candidate optical\nafterglow (Tanvir et al., GCN 16861) with a magnitude of r~24.0 +/- 0.2\n(calibrated to SDSS), indicating that the source faded by ~2.2 mag between\n3.0 hr and 7.8 hr post-burst. The fading confirms that this source is the\noptical afterglow of GRB 140930B. Assuming a single power-law decline\nbetween these two epochs, the decay index is alpha~-2.1.\n\nWe thank Nelson Caldwell for the rapid scheduling of these observations.\"",
  "circularId": 16863,
  "createdOn": 1412146034000,
  "email": "wfong@email.arizona.edu",
  "subject": "GRB 140930B: MMT confirmation of the optical afterglow",
  "submitter": "Wen-fai Fong at U of Arizona  <wfong@email.arizona.edu>",
  "eventId": "GRB 140930B"
}