GCN Circular 24831

P. Schady (Uni. Bath) and J. Bolmer (MPE Garching) report:


We observed the field of GRB 190613B (Fermi trigger 582115625.049376/190613449; GCN #24806, Swift trigger 908329; D'Ai et al., GCN #24807) 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).


Observations started at 09:18 UT on 14 June 2019, 22.4 hrs after the GRB trigger. They were performed at an average seeing of 1.4" and at an average airmass of 1.2.


We detect a single point source in our g'r'i'z'JH images consistent with the reported GRB optical and X-ray afterglow (Beardmore et al., GCN #24812, Marshall et al., GCN #24817). Based on a total 22 min exposure in g'r'i'z' and 22 min in JHK, we estimate the following preliminary magnitudes (all in Vega system):


g' = 22.79 +/- 0.05 mag
r' = 22.05 +/- 0.04 mag
i' = 21.56 +/- 0.05 mag
z' = 21.15 +/- 0.07 mag
J = 20.5 +/- 0.1 mag
H = 20.2 +/- 0.2 mag
K > 19.8 mag


Given magnitudes are calibrated against PanStarrs as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.06 mag in the direction of the burst (Schlafly & Finkbeiner 2011).

We thank the observer astronomer at the MPG 2.2m in La Silla for their help in obtaining these data.