TITLE:   GCN CIRCULAR
NUMBER:  35153
SUBJECT: GRB 231117A: GTC Near-Infrared Observations
DATE:    23/11/21 21:05:30 GMT
FROM:    Alan M Watson at UNAM <alan@astro.unam.mx>

Alan M. Watson (UNAM), Simone Dichiara (PSU), Eleonora Troja
(Università di Roma Tor Vergata), Brendan O’Connor (CMU), Rosa L.
Becerra (UNAM), Nathaniel R. Butler (ASU), Nissim Fraija (UNAM),
William Lee (UNAM), Océlotl López (UNAM), and Margarita Pereyra (UNAM)
report:

We observed the field of GRB 231117A (Laha et al., GCN 35071;
Navaneeth et al., GCN 35072; Beardmore et al., GCN3574; Cattaneo et
al., GCN 35075; Svinkin et al., GCN 35079; Cheung et al., GCN 35081;
Dafcikova et al., GCN 53095; Busman et al. GCN 35138; O'Connor et al.,
GCN 35139) with the EMIR instrument on the GTC telescope from
2023-11-19 19:33 to 19:57 UTC (64.5 to 64.9 hours after the trigger).
We obtained total integrations of 420 in J and 252 in Ks with a seeing
of about 0.8 arcsec.

From our preliminary analysis, the source is detected in all filters
with brightness J = 20.9 +/- 0.1 AB, with an uncertain contribution
from the host galaxy. This value is not corrected for Galactic
extinction.

Further observations are planned.

We thank the staff of the GTC, including Riccardo Scarpa and Antonio
Cabrera, for their help with these observations.