TITLE: GCN CIRCULAR NUMBER: 45508 SUBJECT: GRB 260903A: NOT optical observations and afterglow fading DATE: 26/09/04 00:54:37 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk> D. B. Malesani (DAWN/NBI), J. An (NAOC), G. Corcoran (UCD), A. Saccardi (CEA/Irfu), F. Mustafaj (NOT), O. Stalder (NOT), report on behalf of a larger collaboration: We observed the optical counterpart (Li et al., GCN 45504; Saccardi et al., GCN 45505) of the SVOM/ECLAIRs GRB 260903A (Brunet et al., GCN 45499) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A total of 3x300 s observations were secured in the SDSS r band. The optical afterglow is detected in our images. Preliminary photometry against the Pan-STARRS catalog yields a magnitude r = 22.88 +- 0.16 (AB) on 2026 Sep 4.00 UT, that is 11.45 hr after the trigger. Our measurement indicates significant fading compared to previously reported measurements (Li et al., GCN 45504; Saccardi et al., GCN 45505), thus confirming that this object is the afterglow of GRB 260903A. View this GCN Circular online at https://gcn.nasa.gov/circulars/45508. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...