TITLE: GCN CIRCULAR NUMBER: 43873 SUBJECT: EP260227a: NOT optical observations DATE: 26/02/28 06:51:11 GMT FROM: L. B. He at NAOC <helb@bao.ac.cn> S.Y. Fu (HUST), L.B. He, Z.P. Zhu, J. An, X. Liu, S.Q. Jiang, D. Xu (NAOC), J. P. U. Fynbo (DAWN/NBI), A. L. Bouquin (NOT) report on behalf of a large collaboration: We observed the field of EP260227a (Wang et al., GCN 43869) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. The observations started at 02:20:46 UT, 2026-02-28, i.e. 6.14 hrs after the trigger, and we obtained 3x120 s frames each in Sloan g', r' and i' bands. The previously reported optical counterpart (Eyles-Ferris et al., GCN 43867; Li et al., GCN 43868) was detected in our stacked frames with the following AB magnitudes: | t-mid (hrs) | filter | mag | | ----------- |--------| ------------ | | 6.21 | g' | 21.40 ± 0.20 | | 6.33 | r' | 21.50 ± 0.20 | | 6.46 | i | 21.37 ± 0.12 | calibrated using nearby Pan-STARRS1 dr2 catalog, and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43873. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...