[vsnet-grb-info 23967] GRB 191024A: GROND early upper limits

[GCN Circulars]

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  <jan at bolmer.de>

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).