Luminous early-type field galaxies at z sim 0.4 - I. Observations and redshift catalogue of 581 galaxies

We have compiled a sample of $\sim 9600$ bright, $i\le 18.95$, red, $b_j-r>2$, candidate galaxies in an area of 220 deg$^2$. These are luminous, $L > L^*$, field early-type galaxies with redshifts $0.3 \la z \la 0.6$. We present a redshift catalogue of a sub-sample of 581 targets. The galaxies were selected according to their broadband $b_jri$ colours from United Kingdom Schmidt Telescope plates, and have a surface density on the sky of only $\sim 50 $deg$^{-2}$. Such luminous field galaxies are virtually absent from published redshift surveys and the catalogue provides a large sample of the most luminous normal galaxies, at cosmological distances. The statistical properties of the galaxy spectra, including absorption line and emission line measures, are presented and a composite spectrum constructed. The nature of the sample, combined with the relatively bright apparent magnitudes make the galaxies suitable targets for several key investigations in galaxy evolution and cosmology.