Evolution of faint galaxies

Observational data from near and distant galaxies are compared with theoretical predictions for processes in evolving galaxies. Modelling nominally involves assuming a time dependent rate of star formation in order to match observed colors of star formations with tracks on the H-R diagram. Visual evolutionary effects are confined to luminosity levels, with younger systems appearing brighter, and classifications proceeding according to morphology and redshift. Existing radial velocity surveys are reviewed, as are predictions of true luminosities per unit volume. The results of UV spectrophotometric observations of spiral galaxies at high redshifts, i.e., the K-correction, are discussed in terms of the resolution of available instrumentation, particularly the IUE. Finally, the usage of optical photometry and spectroscopy to measure colors and redshifts is noted to have yielded sufficient data to reject the no-evolution hypothesis.