CCD observations of Abell clusters. V - Isophotometry of 175 brightest elliptical galaxies in Abell clusters

Profiles of major- and minor-axis surface brightness, ellipticity, position angle, and isophote centroid are presently derived from isophotometry for a sample of 175 brightest cluster ellipticals (BCEs). The BCEs' average ellipticity is a sharply rising function of metric radius; less than a fourth of the sample exhibits significant ellipticity decrease with increasing radius. While at radii of less than 16 kpc the BCEs are rounder than the average elliptical, they become too flattened at radii greater than 30 kpc to represent a randomly-oriented oblate-spheroid population. These results indicate that BCE outer regions are dynamically strongly coupled to their either prolate or stringy clusters. 136 refs