TITLE:   GCN CIRCULAR
NUMBER:  32383
SUBJECT: GRB 220711B, GROND observations
DATE:    22/07/13 14:52:45 GMT
FROM:    Ana Nicuesa at TLS Tautenburg  <ana@tls-tautenburg.de>

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

We observed the field of GRB 220711B (D'Ai et al., GCN 32366;
Beardmore et al. GCN 32370) with GROND mounted at the 2.2m MPG
telescope at La Silla Observatory (Chile).

Observations started at 01:53 UT on July 13, 2022, about 32 hr after
the GRB trigger and were on target for  40 minutes. They were performed
at an average seeing of 1.0 arcsec and at an airmass of 1.7.

The fading source discovered by Malesani et al. (GCN 32377) is
detected in the combined JHK images. For the individual bands we can
only provide the following preliminary upper limits (midtime of 2:20
UT):

  g' > 23.0,
  r' > 23.5,
  i' > 23.2,
  z' > 19.8,
  J  > 21.7,
  H  > 21.1,
  K  > 20.1  (AB mag; 3 sigma).

The given limits are derived based on calibrating the optical images
against the SDSS catalog and the JHK data against 2MASS stars.
We thank Sam Kim and Regis Lachaume for excellent support and for
performing the observations.