[vsnet-grb-info 28600] GRB 210822A: GROND observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30703
SUBJECT: GRB 210822A: GROND observations
DATE:    21/08/24 15:19:39 GMT
FROM:    Ana Nicuesa at TLS Tautenburg  <ana at tls-tautenburg.de>

A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg) and
A. Rau (MPE Garching) report:


We observed the field of GRB 210822A (Swift trigger #1069788; Page et al.,
GCN 30677) with GROND mounted at the 2.2m MPG telescope at La Silla
Observatory (Chile).

Observations started at 02:54 UT on August 23, about 17.6 hr after the GRB
trigger. They were performed at an average seeing of 2.2 arcsec and at an
average airmass of 1.2.

Based on combined images with 10 min total exposure, at a mid-time of
03:02 UT on 2021-08-23 for the afterglow (Page et al., GCN 30677; Zheng &
Filippenko, GCN 30679; Butler et al., GCN 30680; Fu et al., GCN 30684; Zhu
et al., GCN 30692; Romanov & Lane, GCN 30701) we derive the following
AB magnitudes:

g' = 20.37 +/- 0.09,
r' = 20.10 +/- 0.05,
i' = 19.92 +/- 0.05.

Given magnitudes are calibrated against Pan-STARRS and   are not corrected
for the expected Galactic foreground extinction corresponding to a
reddening of E(B-V) = 0.14 mag in the direction of the burst (Schlegel et
al. 1998).

We thank Angela Hempel for excellent support and for performing the
observations.