1 Introduction

The Virgo cluster, the nearest rich cluster of galaxies in the northern hemisphere, was surveyed with unprecedented resolution and completeness in the extensive photographic survey carryed out with the DuPont telescope at Las Campanas. Based on this material Binggeli et al. (1985) compiled the Virgo Cluster Catalogue (VCC), which lists 2096 galaxies brighter than $B_{\rm T}\le20.0$ (1323 of which constitute a complete subsample to $B_{\rm T}\le18.0$). This work has served to many important developements, in particular for mapping for the first time the luminosity function of a cluster down to $M_{\rm p}=-13.1$ (assuming a distance modulus of Virgo $\mu=-31.1$, corresponding to the distance of 17 Mpc; see Gavazzi et al. 1999a) and for comparing the various luminosity functions across the entire Hubble sequence (Sandage et al. 1985). In absence of a complete redshift information (by the time of its publication only about 30% VCC galaxies had an actual redshift measurement), the cluster membership was assigned to the individual objects on a purely morphological (surface brightness) basis. Since then the number of available redshifts either from optical (e.g. Binggeli et al. 1985; Grogin et al. 1998; hereafter GGH98) or from radio spectroscopy (e.g. Haynes & Giovanelli 1986; Hoffman et al. 1987; Hoffman et al. 1989; Hoffman et al. 1995; Magri 1994) has increased considerably. Nonetheless the present redshift completeness in this region is still only 65% at $B_{\rm T}\le$ 18.0.

A better redshift completeness exists in the Coma-A1367 supercluster region $11^{\rm h}30^{\rm m}<\alpha<13^{\rm h}30^{\rm m}; 18^{\circ}<\delta<32^{\circ}$, limited however to the shallower magnitude limit of 15.7 of the CGCG catalogue (Zwicky et al. 1961-68). Gavazzi et al. (1999b) counted 1068 redshift measurements out of 1127 CGCG galaxies listed in this region. With the aim of contributing with new redshift measurements in these regions we undertook the spectroscopic survey presented in this paper, which was carryed out during marginally photometric nights. The observations and data reduction are presented in Sect. 2. The new redshifts are given and discussed in Sect. 3.

 

 

Table 1: The spectrograph characteristics

Telescope	run	Spectrograph	dispersion	coverage	CCD type	pix
			Å/mm	Å		$\mu$m
Loiano	Jan.-Feb. 1999	BFOSC	198	4060-7900	$1024\times1024$ TH	19
Loiano	Jan.-Feb. 2000	BFOSC	198	3600-8900	$1340\times1300$ EEV	20
Cananea	Apr. 2000	LFOSC	228	4000-7100	$576\times384$ TH	23
OHP	Mar. 1999	CARELEC	133	3200-7100	$2048\times1024$ EEV	13.5

Figure 1: The distribution in celestial coordinates of 639 Virgo galaxies with $V\leq 3000$  $\rm km~ s^{-1}$(right) and a wedge diagram (left). The filled symbols represent measurements obtained in the present work