GCN Circular 39438
Subject
EP250223a: NOT redshift z = 2.756
Date
2025-02-23T23:17:57Z (14 days ago)
From
Andrew Levan at Radboud University <a.levan@astro.ru.nl>
Via
Web form
Andrew J. Levan (Radboud and Warwick), Luca Izzo (INAF, Naples and DARK/NBI), Daniele B. Malesani (DAWN/NBI and Radboud), Antonio Martin-Carrillo (UCD), Franz E. Bauer (PUC), Peter G. Jonker (Radboud), Benjamin N. Hauptmann (NOT and DTU Space), Yfke Bethlehem (Kapteyn Astronomical Institute, Groningen, and ING), and Dong Xu (NAOC), report on behalf of a larger collaboration:
Further to the identification of the likely optical counterpart (Hauptmann et al., GCN 39436) of EP 250223a (Lian et al., GCN 39429), we obtained spectroscopic observations with the Nordic Optical Telescope, beginning at 21:18 UT. A total of 4x900 s observations were obtained using grism #4.
The observations reveal a strong continuum with a pronounced suppression at ~4550 AA, which we interpret as arising from damped Lyman-alpha absorption. In addition we detect a number of narrow metal lines, among which Fe II, Al II, C II, O I, Si II, which allow us to fix the redshift to z = 2.756.
The spectral shape and redshift, as well as the detection of an X-ray counterpart at a consistent position with Swift (Kennea et al., GCN 39437), secure the source as the counterpart of EP250223a.