GCN Circular 42639

Subject

GRB 251111A: LCO optical observation

Event

GRB 251111A

Date

2025-11-11T07:59:03Z (a day ago)

From

SVOM_group <svomgroup@bao.ac.cn>

Via

Web form

C. Wu (NAOC), L. P. Xin, Xuhui Han, J. T. Palmerio (CEA/Irfu), D. Turpin, A. Saccardi, B. Cordier report on behalf of the SVOM mission team:

We observed the field of GRB 251111A (SVOM/ECLAIRs, Cheng et al. GCN 42637

) with the LCO 1m telescope at Cerro Tololo Inter-American Observatory equipped with the Sinistro instrument. Our observation started at 2025-11-11T05:31:30.632 about 21.21 minutes after the SVOM/ECLAIRs T0 time.

We obtained a sequence of 3x200 s exposures in the SDSS r band. The optical counterpart reported by SVOM/COLIBRÍ (FM-GFT) (López-Cámara et al., GCN 42638

) is clearly detected in our stacked image. We measure an AB magnitude of r = 21.52 ± 0.15 at a midtime of Tmid − T0 = 26.63 min after the trigger.

The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied.

This project is funded by the SVOM collaboration.