Multicolor Images of a Complete z ∼ 1 Sample of 3CR Galaxies

Extract

In order to look at relationships among various optical and radio properties of powerful radio galaxies at high redshifts in a systematic way, we have observed a nearly complete subsample of the Laing et al. (1984; henceforth LRL) revision of the 3CR extragalactic source list. Our sample comprises the 14 radio galaxies in the LRL list with δ < 50° and 0.8 < z < 1.3. We have obtained images of 13 of the 14 galaxies (we are missing 3CR 175.1) in each of three bands. The filters used typically gave ∼ 200 Å (rest-frame) passbands shortward of 3700 Å and longward of 4000 Å (in order to give us a 4000 Å break index), as well as a 50 Å passband centered on the [O II] λ3727 line. The images were obtained with the Galileo/IfA TI 500 × 500 CCD system on the UH 2.2 m and CFHT 3.6 m telescopes on Mauna Kea. Absolute calibrations of the images were based on observations of Gunn-Oke spectrophotometric standard stars through the various filters. The photometry we discuss here used synthetic circular apertures closely matched for each object to those used by Lilly and Longair (1984), who give K magnitudes, at least, and sometimes J and H as well, for all objects in our sample.