TITLE:   GCN CIRCULAR
NUMBER:  45837
SUBJECT: GRB 261007A / EP261007a: LCO optical observations
DATE:    26/10/07 15:16:01 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

A. Saccardi (CEA/Irfu), D. Turpin (CEA/Irfu), S. J. Yin (GXU), C. Wu (NAOC), W. Zhang(PMO), X. Tian (GXU), report on behalf of the SVOM mission team:

We observed the optical counterpart (Zheng et al., GCN 45825; Mohan et al., GCN 45832; Saccardi et al., GCN 45829) of the SVOM/ECLAIRs GRB 261007A / EP261007a (Goto et al., GCN 45824), also detected by EP/WXT (Wen et al., GCN 45828) and Fermi/GBM (Malacaria, GCN 45830), with the LCO 1m telescope at Siding Spring Observatory equipped with the Sinistro instrument.

Our observation started on 2026-10-07 at 13:00:16 UT (about 7.3 hr after the trigger) and we obtained 3x200 s exposures in the SDSS r filter.

The optical candidate is well detected in our images. We measure the following magnitude calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:

r = 19.78 +/- 0.08 AB (mid-time 7.33 hr after the trigger).

This project is funded by the SVOM collaboration.