GCN Circular 10098
Robert Filgas (MPE Garching), Adria Updike (Clemson University), and Jochen Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 091029 (Swift trigger 374210; Grupe et al., GCN #10097) 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 03:57 UT on Oct 29, 4.5 min after the GRB trigger, and are continuing. They were performed at an average seeing of 1.6" and at an average airmass of 1.22. We found a single point source within the 4.8 Swift-XRT error circle reported by Grupe et al. (GCN #10097) at RA (J2000.0) = 04h 00m 42.7 s DEC (J2000.0) = -55d 57' 19 with an uncertainty of 0.5". Based on the first 5.3 min of total exposures in g'r'i'z' and 6.7 min in JHK, we estimate preliminary magnitudes (all in AB system) of g' = 17.72 +- 0.1 mag, r' = 17.45 +- 0.1 mag, J = 17.00 +- 0.08 mag. 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)=0.02 mag in the direction of the burst (Schlegel et al. 1998).