TITLE:   GCN CIRCULAR
NUMBER:  37925
SUBJECT: GRB 241026A: LBT redshift confirmation
DATE:    24/10/28 11:41:05 GMT
FROM:    Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>

L. Izzo (INAF/OAC), O. Kuhn (LBTO), A. Rossi (INAF/OAS), D. B. Malesani (DAWN/NBI and Radboud Univ.), V. D'Elia (ASI/SSDC & INAF-OAR) and F. Cusano (INAF/OAS), report on behalf of a larger collaboration: 

We observed the optical counterpart (Moskvitin et al.,, GCN 37899) of GRB 241026A (Melandri et al., GCN 37896; Trigg, GCN 37917; Zhang et al., GCN 37921) using the Large Binocular Telescope (LBT) located on Mount Graham (AZ, USA). Observations were carried out with the MODS instrument, and consisted of two 600-s spectra taken in each of the red and blue channels, starting on 2024 October 27.204 UT (6.18 hr after the trigger).

Strong continuum is detected, showing a multitude of absorption lines, which we interpret as due to, among others, Si II 1526, Si II* 1533, C IV 1458,1550, Fe II 1600, Al II 1670, Si II 1808, Al III 1854, 1862, all at a common redshift of z = 2.791.

We thus confirm the redshift value measured by Moskvitin et al. (GCN 37916).

We acknowledge support from R. Ansaldi at LBTO.