TITLE: GCN CIRCULAR NUMBER: 26066 SUBJECT: GRB 191024A: GROND early upper limits DATE: 19/10/24 13:47:49 GMT FROM: Jan Bolmer at MPE/Garching J. Bolmer (MPE Garching), and P. Schady (Univ. of Bath), report: We observed the field of GRB 191024A (Swift trigger 931242; Page et al., GCN #26063) 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 04:45:40 UT on 24th October, 3 minutes after the GRB trigger. They were performed at an average seeing of 1.2" and at an average airmass of 1.4. We do not detect a source at the enhanced position of the Swift-XRT afterglow (Beardmore et al., GCN #26064) — down to the following 3-sigma limits (all AB magnitude) — in the stacked images of observations taken between 168 and 5906 seconds post trigger (total integration time of 95 min). g' > 25.5 mag r' > 25.6 mag i' > 24.8 mag z' > 23.4 mag J > 21.9 mag H > 21.4 mag K > 20.2 mag Given limits are calibrated against Sky-Mapper and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.01 in the direction of the burst (Schlafly & Finkbeiner 2011).