Structural Investigations in the Central Part of the Coma Cluster on the Base of Equidensity Diagrams. I
Maximum diameters of galaxies up to 19th magnitude in the center of the Coma cluster are determined by photographic equidensitometry using a photographic plate obtained in the V system. Diameter-magnitude diagrams and ellipticities of the galaxies are derived, photometric corrections are made for tilted objects, and diameter functions are used instead of magnitude functions to describe the general structure of the cluster. The results are compared with those of Rood and Baum (1967, 1968, 1969), who determined the diameters on the basis of visual measurements. It is shown that the present diameters are, on the average, three times larger than those determined by Rood and Baum and that brightness determinations from the diameter-magnitude diagrams by the equidensity method are twice as accurate.