TITLE: GCN CIRCULAR NUMBER: 37039 SUBJECT: EP240804a: VLT/X-shooter spectroscopic redshift DATE: 24/08/05 12:32:31 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk> A. Bochenek (LJMU), D. Xu (NAOC), Z. P. Zhu (NAOC), L. Izzo (INAF-OACn & DARK/NBI), J. T. Palmerio (CEA-Irfu & GEPI/Obs. de Paris), A. Saccardi (GEPI/Obs. de Paris), V. D’Elia (ASI-SSDC), A. De Cia (ESO), S. D. Vergani (GEPI/Obs. de Paris), N. R. Tanvir (U. Leicester), J. An (NAOC), report on behalf of the Stargate collaboration: We obtained observations of the Einstein Probe (EP) fast X-ray transient EP240804a (Wang et al., GCN 37034), using the X-shooter spectrograph at the VLT. The spectra cover the wavelength range of 3000-21000 AA, and consist of four 600-s exposures. Observations started at 2024-08-05, 06:48:20 UT, or about 9.2 hr after the trigger. The transient is detected at a position consistent with the counterpart reported by An et al. (GCN 37035). In a preliminary reduction of the spectra, we clearly detect a continuum over the entire wavelength range and infer a redshift of z = 3.662. We detect a Lya absorption and multiple absorption features, which we interpret as being due to S II, Si II, Si II*, O I, O I*, C II, C II*, Al II, Fe II, Mg II and Al III, Si IV, C IV. We acknowledge expert support from the ESO staff in Paranal, in particular Claudia Paladini and Felipe Gaete Roman. View this GCN Circular online at https://gcn.nasa.gov/circulars/37039. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...