[vsnet-grb-info 14675] GRB140318A: Discovery Channel Telescope Optical Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15989
SUBJECT: GRB140318A: Discovery Channel Telescope Optical Detection
DATE:    14/03/18 06:55:48 GMT
FROM:    John Capone at UMD  <jicapone at astro.umd.edu>

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

We observed the field of GRB140318A (Cenko et al., GCN 15986) with the
Large Monolithic Imager (LMI) on the recently commissioned 4.3m Discovery
Channel Telescope (DCT) at Happy Jack, AZ. We started a sequence of r', i'
and z' images beginning at 2014-03-18 03:32 UTC (approximately 3.5 hours
after the Swift trigger).

A source is clearly detected in all filters at the location of the optical
afterglow (Schulze et al, GCN 15987). Using nearby point sources from SDSS
for calibration, we measure preliminary magnitudes of r' = 21.6 +/- 0.2, i'
= 21.14 +/- 0.06 and z' = 20.86 +/- 0.04 at an average time of ~5 hours
after the GRB. These values are not corrected for Galactic extinction in
the direction of the GRB.

The source shows evidence of fading when compared with the NOT observation,
confirming that this is the optical afterglow.

Additional multi-band observations are ongoing.

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