...

Deceased 1996 September 22.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... studies

Tables 2, 3 and A.1 with their notes and Figs. A.1-A.3 are only available in electronic form at http://www.edpsciences.org

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

...$H_{\rm0}$

$H_{\rm0}$ is the Hubble constant, accepted hereafter as 75 km s$^{\rm -1}$ Mpc^-1.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... NED

http://nedwww.ipac.caltech.edu/ - the NASA-IPAC Extragalactic Database.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

...${\sim}38\pm7\%$)

Here and in other presented fractions the errors are given based on Poisson statistics of numbers of BCGs involved in each group.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... MIDAS

MIDAS is an acronym for the European Southern Observatory package - Munich Image Data Analysis System.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... IRAF

IRAF is distributed by National Optical Astronomical Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.