4. The catalogues

Figure 7: Magnitude histogram in the R band for the 305 galaxies for which we measured velocities (full line) and for the 144 galaxy redshifts taken from the literature (dotted line). The 17 missing galaxies are those for which no magnitude is available

Figure 8: Magnitude histogram in the $b_{\rm J}$ band of the 101 stars initially misclassified as galaxies in the photometric sample used for our target selection

The coordinates and $b_{\rm J}$ magnitudes of the 101 stars misclassified as galaxies are given in Table 3 (available in electronic form only), to avoid further observations of these objects in galaxy surveys.

The velocity data for the galaxies in the field of Abell 496 are given in Table 4 (available in electronic form only). The meaning of the columns is the following:
(1) running number;
(2) to (4) right ascension (equinox 2000.0);
(5) to (7) declination (equinox 2000.0);
(8) heliocentric velocity (cz) in km s^-1;
(9) error on the velocity in km s^-1; for velocities derived from absorption lines, the error is either that stated in the literature or, for our own measurements, that given by the RVSAO IRAF package; for velocities derived from several emission lines, the error was estimated from the dispersion between the velocities derived from the different emission lines; when only one emission line was present and no absorption line redshift was available, the error on the velocity was taken to be the mean internal velocity error;
(10) R band magnitude (see Sect. 3);
(11) and (12) X and Y positions in arcseconds relative to the center assumed to have coordinates:
$\alpha_{2000.0} = 04^{\rm h}33^{{\rm mn}}37.9^{\rm s}, \delta_{2000.0} = -13^\circ 15'47''$;
(13) distance to the cluster center in arcseconds;
(14) Tonry & Davis parameter;
(15) label indicating the means of determination of the redshift: 0=derived from absorption lines, 1=derived from emission lines;
(16) label indicating the origin of the data: 1=our data, 2=Quintana & Ramírez (1990), 3=Malumuth et al. (1992), 4=Proust et al. (1987), 5=Huchra et al. (1992); note that the catalogue by Malumuth et al. (1992) includes previous measurements by Quintana et al. (1985) and Zabludoff et al. (1990);
(17) reference to the galaxy number in the various catalogues; for our own data (label 1 in Col. 16), the number appearing in this column is that of the photographic plate catalogue by Slezak et al. (1999), Table 1; for data taken from the literature, the first number is that of the previously published catalogue (or the name for CfA galaxies), the second that of the photographic plate catalogue by Slezak et al. (1999) whenever the identification was possible.