TITLE: GCN CIRCULAR NUMBER: 42031 SUBJECT: GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592 DATE: 25/09/30 09:22:02 GMT FROM: Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr> A. Saccardi (CEA/Irfu), N. Habeeb (U. Leicester), D. B. Malesani (DAWN/NBI and Radboud), B. Schneider (LAM), N. R. Tanvir (Leicester), report on behalf of the Stargate collaboration: We observed the object visible in the Legacy Survey underlying the position of the optical/NIR afterglow (Schneider et al., GCN 41794; Li et al., GCN41798) of GRB 250910A / EP250910a (Ma et al., GCN 41769; Liu et al., GCN 41776; Hubert et al., GCN 41842) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. A spectrum covering the wavelength range 3000-21000 AA was secured, with a total exposure time 2x1440 s in each of the UVB, VIS, and NIR arms. Our observation started at 03:01:23 UT on 2025 September 30, i.e. about 20 days after the SVOM trigger. Emission lines are detected in the visible and near-infrared arms, which we identify as H-alpha, the [O III] 4959, 5007 doublet, H-beta, and the [O II] 3726, 3729 doublet, all at a common redshift of z = 0.592. We suggest this to be the redshift of the host galaxy of GRB 250910A / EP250910a. We acknowledge excellent support from the ESO staff in Paranal, in particular Elisa Rita Garro, Rodrigo Romero and Jonathan Smoker. View this GCN Circular online at https://gcn.nasa.gov/circulars/42031. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...