GCN Circular 43621
Subject
GRB 260204A: LCO optical afterglow detection
Event
Date
2026-02-05T10:45:38Z (5 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
D. B. Malesani (DAWN/NBI and Radboud), D. Turpin (CEA/Irfu), A. Saccardi (CEA/Irfu), B. Cordier (CEA/Irfu), M. Pillas, M. Dennefeld (IAP), report on behalf of the SVOM mission team:
Following the report of an optical counterpart (Li et al., GCN 43620; see also the X-ray detection at https://www.swift.ac.uk/SVOM/SVOM_FIELD00057/) of the SVOM GRB 260204A (Pillas et al. GCN 43613), we inspected again our images taken with the LCO telescope at the Siding Spring Observatory (Turpin et al., GCN 43616).
The optical counterpart is detected in our images, and we measure the following magnitudes:
r = 20.26 +- 0.21 AB (mid-time 25.7 min after the trigger);
z = 19.49 +- 0.25 AB (mid-time 38.4 min after the trigger).
We note that these measurements are close to the sensitivity limit of our images, and consistent with the 5-sigma upper limits reported in our previous circular (Turpin et al., GCN 43616). The above measurements are not corrected for Galactic extinction.
Compared to the SVOM/VT measurement (taken at a mean epoch ~74 min after the GRB), our data indicate only marginal decay between the two observations.