GCN Circular 16899

S. Schmidl (TLS Tautenburg), J. F. Graham, and J. Greiner
(both MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 141004A (Swift trigger 614390; V. D'Elia et
al., GCN #16878) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

We detect the afterglow at the UVOT position reported by V. D'Elia et al.
(GCN #16878). From coadded observations, starting on October 06 and
spanning from 05:31 to 09:09 UT, we report the following preliminary AB
magnitudes of:

g' = 24.6 +/- 0.3,
r' = 24.0 +/- 0.2,
i' = 23.5 +/- 0.2, and
z' = 23.4 +/- 0.2.

Given magnitudes are calibrated against GROND zeropoints and
are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.32 mag in the direction of the
burst (Schlegel et al. 1998).