New high-redshift radio galaxies from the MIT-Green Bank catalog

We present optical identifications and redshifts for 17 new hi,oh-redshift radio sources. Fifteen of these sources are radio galaxies; the remaining t wo are high-redshift, steep-spectrum, radio-loud quasars. These objects wer e discovered as part of an ongoing study of compact (theta < 10 "), moderat ely steep spectrum (alpha(1.4 GHz)(4.8 GHz) > 0.75, S-v proportional to v(- alpha)) sources from the MIT-Green Bank (MG) radio catalog (S-5 (GHz) great er than or similar to 50 mJy). Spectra for the optical counterparts were ob tained at the W. M. Keck Telescopes and are among the optically faintest ra dio galaxies thus far identified. Redshifts range between 0.3 and 3.6, with 13 of the 17 at redshifts greater than 1.5. Combining these new radio gala xies with two published MG radio galaxy spectra, we synthesize a composite MG radio galaxy spectrum and discuss the properties of these galaxies in co mparison with other, more powerful, radio galaxies at similar redshifts. We suggest a radio power-ionization state relation.