TITLE:   GCN CIRCULAR
NUMBER:  17914
SUBJECT: GRB150607A: Discovery Channel Telescope Optical Observations
DATE:    15/06/08 17:14:26 GMT
FROM:    Vicki Toy at UMD  <vtoy@astro.umd.edu>

V. Toy (UMD), J. Capone (UMD), S.B. Cenko (NASA-GSFC), S. Veilleux (UMD),
A. Cucchiara (NASA-GSFC), E. Troja (NASA-GSFC),  and A. Kutyrev (NASA-GSFC)
report on behalf of a larger collaboration:

We observed the field of GRB150607A (Swift trigger 642620, D'Elia et al.,
GCN 17904) with the Large Monolithic Imager (LMI) on the 4.3m Discovery
Channel Telescope (DCT) at Happy Jack, AZ from 2015/06/08 03:42 to
2015/06/08 04:35 UTC (starting 19.8 hours after the trigger). A source is
clearly detected at the location of the optical afterglow in r', i', and
z'.  Using nearby point sources from USNO-B1.0 for calibration, we measure
r' = 22.03 +/- 0.03.

This magnitude is reported in AB magnitude and is not corrected for
Galactic extinction in the direction of the GRB.

Compared to NOT observations on 06/07 (Kruehler & Djupvik, GCN 17908) the
afterglow has a decay index of ~ t^-1.1.

We thank the staff of the Discovery Channel Telescope for assistance with
these observations.