GCN Circular 38000

S. Antier (OCA), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas),
William H. Lee (UNAM), D. Akl (AUS), Jean-Luc Atteia (IRAP), Nathaniel R.
Butler (ASU), Damien Dornic (CPPM), J.-G. Ducoin (CPPM), Francis Fortin
(IRAP), Simona Lombardo (LAM), Francesco Magnani (CPPM), and Margarita
Pereyra (UNAM) report:

We imaged again the field of GRB 241030A detected by Fermi/GBM, Swift/BAT,
and Swift/XRT (Fermi GBM Team, GCN Circ. 37955
Not found
 
 
; Klingler et al., GCN Circ.
37956
Not found
 
 
) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at
the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in
Mexico.

We observed with the engineering test camera in a red filter that
approximates SDSS r. The data were reduced using custom software and then
analysed and calibrated against the PS1 catalog using the STDWeb service
(Karpov et al. 2022).

In 1200 seconds of exposure from 2024-10-31 01:46:50 to 02:10:56 UTC (0.83
to 0.85 days after the trigger), we detect the optical counterpart with an
AB magnitude of:

r = 19.95 +/- 0.06

This magnitude is consistent with the last optical observations reported
(GCN Circ. 37993
Not found
 
 
, 37976
Not found
 
 
, 37966
Not found
 
 
 ).

Further observations are planned.

We warmly thank the COLIBRI engineering team and the staff of the
Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir