Photometric redshifts of galaxies

The authors describe a photometric method for measuring thousands of redshifts of 22 mag galaxies with a charge-coupled detector. All objects in a field are photometered between 400 and 950 nm with six filters. The data for each object are matched with colors of a set of fiducial objects, which are several types of galaxies at many redshifts and several types of stars; the object is identified as the galaxy or the star represented by the fiducial object that matches most closely. The photometric redshifts of the galaxies in the field of the cluster 0024+1654 are compared with the spectroscopic redshifts of Dressler, Gunn, and Schneider. Agreement is found for 30 out of 34 galaxies.