TITLE:   GCN CIRCULAR
NUMBER:  45395
SUBJECT: GRB 260818A: LCO optical upper limits
DATE:    26/08/18 15:08:30 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

Y.Y. Shi (GXU), C. Wu, L.P. Xin (NAOC), A. Saccardi, D. Turpin (CEA/Irfu), Clara Plasse (HKU), Donghua Zhao (NAOC), report on behalf of the SVOM mission team:


We observed the field of GRB 260818A (SVOM burst-id sb26081801) detected by SVOM (Yin et al., GCN 45391) with the LCO 1m telescope at Teide Observatory and South African Astronomical Observatory equipped with the Sinistro instrument.

Our observation started on 2026-08-18 at 01:46:28.00 UT (about 41.87 min after the trigger) and we obtained 6x200 s exposures in the SDSS r and 3x200 s exposures in the PS1 zs filter.

No credible uncatalogued source was detected in our stacked frames in the ECLAIRs localization region as also reported by SVOM/COLIBRÍ (Ducoin et al., GCN 45393). 

We measure the following upper limits calibrated against the DESI Legacy Imaging Surveys DR10 catalog, and not corrected for Galactic extinction:

r > 21.8 AB (5-sigma, mid-time 1.01 hr after the trigger),
z > 20.5 AB (5-sigma, mid-time 1.14 hr after the trigger).

This project is funded by the SVOM collaboration.