TITLE: GCN CIRCULAR NUMBER: 43662 SUBJECT: GRB 260208A: NOT spectroscopic redshift z = 2.36 DATE: 26/02/09 10:13:18 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com> Dimple (U. Birmingham), D. B. Malesani (DAWN/NBI and Radboud), A. de Ugarte Postigo (LAM), A. Saccardi (CEA/Irfu), G. Corcoran (UCD), B. P. Gompertz (U. Birmingham), L. Izzo (INAF/OAC and DARK/NBI), A. Martin-Carrillo (UCD) and S. Bijavara Seshashayana (NOT and Malmo Univ.) report on behalf of a larger collaboration: We observed the optical counterpart AT2026ciw (Podesta et al., GCN 43640; Wortley et al., GCN 43641; Ma et al., GCN 43655; Ahumada et al., GCN 43657, Dimple et al., GCN 43661) of the GRB 260208A detected by Fermi (Fermi GBM Team, GCN 43635; Sonawane et al., GCN 43642; Longo et al., GCN 43645) and GECAM-B (Luo et al., GCN 43658), which was also detected in X-rays (Dichiara et al., GCN 43652). Observations started at 05:45:58 UT on 9 February 2026 (24.64 hr after the burst) and consisted of 4x1200 s exposures with grism 4, covering the wavelength range between 3200 and 9600 Å. From a preliminary reduction of the spectrum, a trough due to Lya absorption is visible at 4080 AA. From the detection of multiple absorption features, which we interpret as due to O I, C II, Si IV, Si II, C IV, Fe II, Al II, and Al III, we infer a redshift of z = 2.36. View this GCN Circular online at https://gcn.nasa.gov/circulars/43662. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...