TITLE:   GCN CIRCULAR
NUMBER:  35389
SUBJECT: GRB 231216A: REM NIR upper limits
DATE:    23/12/17 13:53:14 GMT
FROM:    Matteo Ferro <matteo.ferro@inaf.it>

M. Ferro, R. Brivio, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) on behalf of the REM team, report:

We observed the field of GRB 231216A (Sbarrato et al., GCN 35378) with the REM 60cm robotic telescope located at the ESO Observatory of La Silla (Chile). The observations were carried out in the g,r,i,z, J,H,K bands, starting on 2023 Dec 17 at 00:40:48 UT (i.e. about 6.09 hours after the Swift trigger) and lasted for about 1 hour.
From preliminary analysis, we do not find any source at the XRT position (Sbarrato et al., GCN 35378), down the the following 3 sigma upper limits:

H > 16.7 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 6.52 h after the GRB trigger;

K > 16.3 (Vega; calibrated against the 2MASS catalogue)
at a mid time of t-t0 ~ 6.61 h after the GRB trigger.