The REFLEX galaxy cluster survey^*,**

VIII. Spectroscopic observations and optical atlas,

¹ INAF – Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (LC), Italy e-mail: luigi.guzzo@brera.inaf.it
² Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85740 Garching, Germany
³ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
⁴ Observatori Astronomic – Universitat de Valencia, Edificio de Institutos de Investigacion, Aptdo. Correos 22085, 46071 Valencia, Spain
⁵ Physics Department, University of Durham, South Road, Durham DH1 3LE, UK
⁶ CEA Saclay, Service d'Astrophysique, Gif-sur-Yvette, France
⁷ Institute for Astro- and Particle Physics, Universität Innsbruck, 6020 Innsbruck, Austria
⁸ European Southern Observatory, 85748 Garching, Germany


Received: 21 August 2008
Accepted: 16 December 2008

Abstract

We present the final data from the spectroscopic survey of the ROSAT-ESO Flux-Limited X-ray (REFLEX) catalog of galaxy clusters. The REFLEX survey covers 4.24 steradians (34% of the entire sky) below a declination of δ = +2.5⁰ and at high Galactic latitude (|b| > 20°). The REFLEX catalog includes 447 entries with a median redshift of 0.08 and is better than 90% complete to a limiting flux f_X = 310^-12 erg s^-1 cm^-2 (0.1 to 2.4 keV), representing the largest statistically homogeneous sample of clusters drawn from the ROSAT All-Sky Survey (RASS) to date. Here we describe the details of the spectroscopic observations carried out at the ESO 1.5 m, 2.2 m, and 3.6 m telescopes, as well as the data reduction and redshift measurement techniques. The spectra typically cover the wavelength range 3600–7500 Å at a two-pixel resolution of ~14 Å, and the measured redshifts have a total rms error of ~100 km s^-1. In total we present 1406 new galaxy redshifts in 192 clusters, most of which previously did not have any redshift measured. Finally, the luminosity/redshift distributions of the cluster sample and a comparison to the no-evolution expectations from the cluster X-ray luminosity function are presented.