TITLE:   GCN CIRCULAR
NUMBER:  31522
SUBJECT: GRB 220117A, GROND observations
DATE:    22/01/24 11:56:35 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 the short GRB 220117A (Melandri et al., GCN
31466) with GROND mounted at the 2.2m MPG telescope at La Silla
Observatory (Chile).

Observations started at 02:55 UT on January 19, about 34.5 hr after the
GRB trigger. They were performed at an average seeing of 1.3 arcsec and at
an airmass of 1.0.

Inside the XRT error circle (Beardmore et al., GCN 31472),  the
reported optical transient (Palmerio et al., GCN 31480;  Strausbaugh
et al., GCN 31481) is not detected anymore down to the following upper
limits (AB mags; 3 sigma):

g' > 23.2,
r' > 23.4,
i' > 23.0,
J  > 21.4,
H  > 21.1,
K  > 19.3.

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