GCN Circular 9169
P. Afonso (MPE Garching), S. Klose (Tautenburg) T. Kruehler and J.Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of GRB 090419 (Swift trigger 349592, G. Stratta et al.,GCN #9161) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile). Observations started on 19 Apr. 2009 at 23:12 UT, 9.5 h after the burst. Inside the enhanced XRT error circle (J.P. Osborne et al., GCN #9164) we detect a single faint source in the z' and J band at: RA (J2000.0) = 13:07:43.13 DEC (J2000.0) = -75:36:22.4 with an uncertainty of 0.5" in each coordinate. Preliminary photometry yields the following AB magnitudes and upper limits in stacked images: Filter T_mid[h] Exp[s] AB Mag MagErr ---------------------------------------- g 11.5792 12x369 >24.6 r 11.5792 12x369 >25.1 i 11.5792 12x369 24.9 0.5 z 11.5792 12x369 24.2 0.1 J 11.5859 360x10 23.0 0.2 H 11.5859 360x10 >22.1 K 11.5859 360x10 >21.2 The quoted error is statistical only. There is an additional systematic error in the absolute calibration using the GROND zeropoints and 2MASS field stars which is expected to be in the 0.2 mag range. Quoted magnitudes are not corrected for the significant Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.30. Given the lack of information about variability and the rather high density of foreground stars we cannot definitely associate this source with GRB 090419 at this point. Because of the high Galactic foreground extinction, the upper limits in g'r' as well as the i'-z' color are not constraining, and the redshift is only constrained to below about 5.