TITLE: GCN CIRCULAR NUMBER: 38593 SUBJECT: EP241217a: Gemini-North spectroscopic redshift z = 4.59 DATE: 24/12/17 16:27:32 GMT FROM: Andrew Levan at Radboud University a.levan@astro.ru.nl
A. J. Levan (Radboud/Warwick), J. A. Quirola-Vasquez (Radboud), J. C. Rastinejad (Northwestern), D. B. Malesani (DAWN/NBI & Radboud), P. G. Jonker (Radboud), A. Martin-Carrillo (UCD) report for a larger collaboration:
Following the detection of EP241217a (Zhou et al. GCN 38586) and its optical counterpart (Levan et al., GCN 38587; Izzo & Malesani, GCN 38588, Fan et al. GCN 38592) we obtained 1600 s of optical spectroscopy with GMOS-N on Gemini-N and the R400 grating. Spectra cover the range ~5500-9500 AA.
A preliminary reduction of the data shows a bright continuum with a strong break at ~6820 AA, along with several narrow absorption lines, which we interpret as due to Si II, C II, weak C IV, Fe II, Al II, all at a common redshift of z = 4.59 (based on a provisional wavelength calibration). We suggest this is the redshift of EP241217a.
We thank the staff of Gemini-North for the rapid execution of these observations. This work made use of the GRBspec database at http://grbspec.eu (de Ugarte Postigo et al. 2014, doi:10.1117/12.2055774).
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