Studies of rich clusters of galaxies - II. The structure and luminosity function of the cluster A 1413.

Magnitudes have been measured by photographic photometry for galaxies within 5 arcmin of the centre of the very rich cluster Al 413. The differential luminosity function shows a maximum at an absolute total V magnitude of -2130. The absolute magnitude difference between this and the brightest cluster member is 3 59, which is closely consistent with the correlation of Bautz & Abell between this parameter and cluster richness and form type. There is a significant difference between the distributions of the bright and faint galaxies; the former have a distribution consistent with spherical symmetry while the fainter galaxies show a prolate distribution aligned with the major axis of the brightest cluster member. Counts in the field of the cluster show that this effect extends over most of the cluster volume.