GCN Circular 42988
Subject
GRB 251203C: LCO optical afterglow confirmation
Event
Date
2025-12-04T14:54:55Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
D. Turpin, A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), J. T. Palmerio (CEA/Irfu), L. P. Xin, C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Brunet, N. A. Webb (IRAP), report on behalf of the SVOM mission team:
Following the report of an optical counterpart by SVOM/VT (Li et al., GCN 42987) of the SVOM GRB 251203C (Brunet et al., GCN 42976), we inspected again our stacked image from LCO (Turpin et al., GCN 42980).
The VT candidate afterglow is detected in our r-band image. At a mean epoch of 37 min after trigger, we measure an SDSS r-band magnitude of r = 19.91 +/- 0.14 (AB, which is significantly brighter than the SVOM/VT magnitudes (despite the filter system difference) measured at a later epoch (> 3.3 hr after trigger).
This further confirms that this source is the optical afterglow of GRB 251203C.
The z-band upper limit reported by Turpin et al. (GCN 42980) is still confirmed.
This project is funded by the SVOM collaboration.