TITLE:   GCN CIRCULAR
NUMBER:  15904
SUBJECT: GRB 140301A: GROND Detection of the Optical/NIR Afterglow
DATE:    14/03/02 11:43:10 GMT
FROM:    Jonny Elliott at MPE/GROND  <jonnyelliott@mpe.mpg.de>

J. Elliott (MPE Garching), S. Schmidl (TLS Tautenburg), J. Greiner (also
MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 140301A (Swift trigger 589590; Page et al.,
GCN #15896) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started at 00:07 UT on 2nd March 2014, 9.72 hrs after the GRB
trigger. They were performed at an average seeing of
2.2" and at an average airmass of 1.3.

We find a single point source within the 1.9" refined Swift-XRT error
circle reported by Goad et al. (GCN #15898) and confirm the source found
by Kruehler et al. (GCN #15899, #15900).

Based on an exposure of 2.5 hours we estimate preliminary magnitudes (AB
system) of

g' = 24.2 +/- 0.2,
r' = 23.8 +/- 0.2,
i' = 23.2 +/- 0.2,
z' = 22.4 +/- 0.2,
J  > 21.8,
H  > 21.3, and
K  > 20.6.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E(B-V) = 0.03 mag in the
direction of the burst (Schlegel et al. 1998).