TITLE:   GCN CIRCULAR
NUMBER:  38619
SUBJECT: GRB 241217A/EP241217b: REM optical/NIR upper limits
DATE:    24/12/18 13:52:17 GMT
FROM:    Riccardo Brivio at INAF-OAB <riccardo.brivio@inaf.it>

M. Ferro, R. Brivio, P. D’Avanzo (INAF-OAB), D. B. Malesani (DAWN/NBI and Radboud Univ.), S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 241217A detected by SVOM (Brunet et al., GCN 38594), also detected by Swift-XRT (Williams et al., GCN 38599) and EP-WXT (Zhou et al., GCN 38606) with the REM 60cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, K bands, starting on 2024 December 18 at 03:02:28 UT (i.e. 10.1 hours after the SVOM trigger), and lasting for about 1.5 hour.

From preliminary photometry we do not detect any optical or NIR counterpart at the XRT position down to the following 3sigma magnitude upper limits:

r > 20.9 (AB; calibrated against the Pan-STARRS catalogue)
at a mid-time of t - t0 = 10.9 hr after the trigger,

H > 16.6 (Vega; calibrated against the 2MASS catalogue) 
at a mid-time of t - t0 = 10.8 hr after the trigger.