TITLE:   GCN CIRCULAR
NUMBER:  45399
SUBJECT: GRB 260818B: LCO optical upper limits
DATE:    26/08/19 03:42:13 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

Y.Y. Shi (GXU), C. Wu, L.P. Xin (NAOC), A. Saccardi, D. Turpin (CEA/Irfu), Bertrand Cordier (CEA), Hatsune Goto (RIKEN, CEA), report on behalf of the SVOM mission team:


We observed the field of GRB 260818B (SVOM burst-id sb26081807) detected by SVOM (Cordier et al., GCN 45398) with the LCO 1m telescope at South African Astronomical Observatory equipped with the Sinistro instrument.

Our observation started on 2026-08-18 at 23:44:55 UT (about 3.56 hr after the trigger) and we obtained 3x200 s exposures in the SDSS r and PS1 zs filter.

In the stacked image, we do not detect any new source within the SVOM/ECLAIRs error box. We measure the following upper limits calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:

r > 21.9  AB (5-sigma, mid-time 3.65 hr after the trigger),
z > 19.7  AB (5-sigma, mid-time 3.65 hr after the trigger).

This project is funded by the SVOM collaboration.