GCN 44626: GRB 260515A: NOT optical observations.

2026-05-15T21:31:23.663Z | rev 2 | event: GRB 260515A

L. B. He (NAOC), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), A. Saccardi (CEA/Irfu), B. Schneider (LAM), L. Fuglsang (NOT), A. S. Mårtensson (NOT and DTU), report on behalf of a larger collaboration:

We observed the optical counterpart (He et al., GCN 44623; Saccardi et al., GCN 44624; Sosnovskij et al., GCN 44625) of the SVOM/ECLAIRs GRB 260515A (Brunet et al., GCN 44622) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument.

In a single 300-s exposure commencing on May 15.8696 UT (1.73 hr after trigger), the optical afterglow is well detected in our images, with an AB magnitude of r = 20.22 +- 0.04 (calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction).