TITLE:   GCN CIRCULAR
NUMBER:  38206
SUBJECT: GRB 241113A: REM detection of the optical/NIR afterglow
DATE:    24/11/13 19:34:00 GMT
FROM:    Matteo Ferro at INAF-OAB <matteo.ferro@inaf.it>

M. Ferro, Y.-D. Hu, S. Covino, R. Brivio, P. D’Avanzo, D. Fugazza (INAF-OAB), L. Izzo (INAF-OACn and DARK/NBI), and A. Melandri (INAF-OAR) report on behalf of the REM team:

We observed the field of GRB 241113A (Siegel et al., GCN #38194; Goad et al., GCN #38198) 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 and K bands, starting on 2024 Nov 13 at 08:03:10 UT (i.e. about 15 minutes after the Swift trigger) and lasted for about 1.75 hours.

The optical afterglow is detected in the r band at a position coincident with that reported by Swift-UVOT (Siegel et al., GCN #38194) and other optical observations (Francile et al., GCN #38195, Huertas Ferrer et al., GCN #38197; Izzo et al., GCN #38201). The NIR afterglow is detected in the H band at a position consistent with the optical counterpart.
From preliminary photometry, we derive the following magnitudes:

r = 18.7 +/- 0.3 (AB; calibrated against the Pan-STARRS catalogue)
at a mid-time of ~ 37 minutes after the trigger,

H = 15.5 +/- 0.2 (Vega; calibrated against the 2MASS catalogue) 
at a mid-time of ~ 26 minutes after the trigger.