GCN Circular 44916
Subject
EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
Event
Date
2026-06-11T15:26:01Z (2 days ago)
From
Agnes van Hoof at Radboud University <agnes.vanhoof@ru.nl>
Via
Web form
A. P. C. van Hoof (Radboud), J. Sanchez-Sierras (Radboud), P. G. Jonker (Radboud), G. Corcoran (UCD), A. J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), report on behalf of a larger collaboration:
We observed the likely host galaxy of EP260601a/GRB 260601B (Yang et al., GCN 44766; Yu et al., GCN 44767; Wang et al., GCN 44768; Waratkar et al., GCN 44771; Sugita et al., GCN 44773) that is at the position of the optical counterpart (Liu et al., GCN 44764; Guelfand et al., GCN 44765; Li et al. GCN 44769) using the ESO Very Large Telescope (VLT) equipped with the X-shooter spectrograph. The spectrum covers the wavelength range of 3000 - 24000 AA with total exposure times of 2910, 2980 and 3000 s in the UVB, VIS and NIR arms, respectively. The observation started on 2026-06-11 at 07:39:12 UT, i.e. ~10 days after the event.
We detect clear emission lines in the spectrum, which we identify as the [O II] 3726, 3729 doublet (resolved), H-gamma, and [O III] 5008 at a redshift of z = 1.068. We suggest that this is the redshift of the host galaxy of EP260601a.
We thank the ESO staff at Paranal for their excellent support, in particular Celia Desgrange, Claudia Paladini, Francisco Caceres, and John Pritchard.