TITLE: GCN CIRCULAR NUMBER: 38527 SUBJECT: GRB 241209D: REM optical/NIR upper limits DATE: 24/12/10 16:46:08 GMT FROM: Riccardo Brivio at INAF-OAB riccardo.brivio@inaf.it
R.Brivio, M. Ferro, P. D’Avanzo, Y.-D. Hu, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 241209D detected by Swift/BAT (Parsotan et al., GCN 38489) and Fermi/GBM (Fermi GBM team, GCN 38488) 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 10 at 06:54:39 UT (i.e. 19.9 hours after the Swift trigger), and lasting for about 1 hour.
From preliminary photometry we do not detect the optical counterpart (Ducoin et al., GCN 38505) in the optical and NIR images at the Swift-XRT enhanced position (Goad et al., GCN 38491) down to the following 3sigma magnitude upper limits:
r > 20.3 (AB; calibrated against the PanSTARRS catalogue) at a mid-time of t - t0 = 20.4 hr after the trigger,
J > 18.1 (Vega; calibrated against the 2MASS catalogue) at a mid-time of t - t0 = 20.5 hr after the trigger.
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