A. Cucchiara (NASA-GSFC),S.B. Cenko (NASA-GSFC), J. Capone (UMD),
V. Toy (UMD), E. Troja (NASA-GSFC), A. Kutyrev (NASA-GSFC), S. Veilleux
(UMD), and S. Gezari (UMD) report on behalf of a larger collaboration:
"On September 08.37UT (approximately 16.5h after the discovery) we observed
the optical counterpart of GRB 140907A (Krimm et al. GCN 16788, Xu et al.
GCN 16789, Kuin et al. GCN 16791) with the Large Monolithic Imager (LMI) on
the 4.3m Discovery Channel Telescope (DCT) at Happy Jack, AZ. We observed in
g', r', and i' bands for a total of 6, 6 and 4 minutes respectively.
Using a set of stars from the APASS catalogue we derived the following
magnitude for the afterglow:
g' = 21.54 +- 0.17
r' = 20.92 +- 0.15
i' = 20.42 +- 0.16
We thank the DCT staff, in particular S. Strosahl and H. Larson for
their support in performing these observations."