Narrow-band photometry and the evolution of galaxies

A description is provided of a new approach to the use of intermediate-band (FWHM = 200 A) filters in extragalactic research. The employed photometric system vz, bz, yz essentially imitates, at the redshift of the cluster in question, the Stromgren v, b, y passbands. Certain disadvantages of the system are often more than compensated for by the fact that a large number of galaxies can be covered in a few exposures. Attention is given to the CCD observations of three clusters of galaxies, the photometric reduction of CCD frames, stellar colors, estimation of the influence of reddening, the discrimination of foreground and background objects, the use of morphological information as a selection criterion, the results of observations, and the fitting of the theoretical models of spectral evolution. 8 references