GCN Circular 9794

GRB 090814: GROND Detection of an Optical Afterglow Candidate 

Adria Updike (Clemson University), Felipe Olivares, Paulo Afonso,
Abdullah Yoldas, Jochen Greiner (all MPE Garching) report on behalf of
the GROND team: 

We observed the field of GRB 090814 (Swift trigger 359951; Ukwatta et
al., GCN #9793
Not found
 
 
) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La
Silla Observatory (Chile). 

Observations started at 00:59 UT on Aug 14 2009, 7 minutes after the
GRB trigger. They were performed at an average seeing of 1" and at an
average airmass of 2.2. 

We found a single point source within the Swift-XRT error circle
reported by Ukwatta et al. (GCN #9793
Not found
 
 
) at 

RA (J2000.0) = 15 h 58 m 26.35 s
DEC (J2000.0) = +25d 37' 52.4" 

with an uncertainty of 0.5". The candidate afterglow has the following
preliminary AB magnitudes obtained from a first 140s g'r' exposure and
240s in the nIR: 

g' = 21.62 +/- 0.04
r' = 21.21 +/- 0.04
J > 21.1
H > 19.2 

calibrated against SDSS and 2MASS catalogs. No extinction correction
was applied. Ongoing data reduction suggests the source is fading.