GCN Circular 16863
W. Fong (U. Arizona), M. Calkins (SAO), and E. Berger (Harvard) report: "We observed the location of the short-duration GRB 140930B (De Pasquale et al., GCN 16857) with MMTCam mounted on the 6.5-m MMT starting on 2014 Oct 1.144 UT (7.76 hr post-burst). We obtained 4x300-sec of r-band observations in 1" seeing. We detect a source at the position of the candidate optical afterglow (Tanvir et al., GCN 16861) with a magnitude of r~24.0 +/- 0.2 (calibrated to SDSS), indicating that the source faded by ~2.2 mag between 3.0 hr and 7.8 hr post-burst. The fading confirms that this source is the optical afterglow of GRB 140930B. Assuming a single power-law decline between these two epochs, the decay index is alpha~-2.1. We thank Nelson Caldwell for the rapid scheduling of these observations."