GCN Circular 37013
Subject
EP240801a: GTC spectroscopy and absorption redshift
Date
2024-08-02T10:44:40Z (6 months ago)
From
Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>
Via
Web form
J. Quirola-Vásquez (Radboud Univ.), J. van Dalen (Radboud Univ.), D. B. Malesani (DAWN/NBI and Radboud Univ.), P. G. Jonker (Radboud Univ), A. J. Levan (Radboud Univ. & Warwick Univ.), F. E. Bauer (PUC), M. E. Ravasio (Radboud Univ.), D. Mata Sanchez (IAC), M. A. P. Torres (IAC), report on behalf of a larger collaboration:
We observed the optical counterpart of EP240801a (Zhou et al., GCN 36997; Fu et al., GCN 36998) using the 10.4 m GTC located in La Palma, Canary Islands. Observations started on 2024 Aug 2.169 UT (0.79 days after the EP trigger), consisted of 4 exposures of 1200 s each, and were carried out using grism R1000R, which covers the wavelength range 5100-10000 AA. The counterpart magnitude was r = 21.98 +- 0.05 (AB) as measured in a 30-s acquisition image, calibrated against nearby Pan-STARRS sources.
Continuum is well detected over the entire wavelength range. Several absorption lines are visible, which we interpret as due to Mg II and Fe II at a common redshift z = 1.673, which we suggest to be the likely redshift of EP240801a.
We acknowledge excellent support from the GTC staff, in particular Stefan Geier and Antonio Luis Cabrera Lavers.