Samples of galaxies selected from nearby clusters are generally complete over a large range of observable properties due to their known distance. They therefore provide a natural basis for the statistical study of key physical properties such as star-formation history, gas content, metallicity, and cosmic ray production rate over a considerable dynamic range. In particular, the proximity and high galactic latitude of the Virgo cluster make it a unique laboratory for the statistical study of a complete volume-limited sample of late-type galaxies, including a full representation of quiescent and dwarf galaxies. Furthermore, compared to relaxed clusters, the effect of the cluster environment may not be so pronounced in the periphery regions of the dynamically young Virgo cluster. Most of the outlying Virgo galaxies may be falling in for the first time (e.g. Tully & Shaya 1984; Gavazzi et al. 1991), and so may have properties more representative of field galaxies. Consequently, comparison of a deep, complete sample of Virgo cluster galaxies from the cluster-periphery with identically selected counterparts from the cluster core and (for the brighter spirals) with fully isolated galaxies should constitute a sensitive statistical measure of the effect of the cluster environment on physical processes in the galaxies.
These considerations have prompted us to embark upon a program to measure a deep, complete sample of 117 late-type Virgo cluster galaxies selected from the Virgo Cluster Catalogue of Binggeli et al. (1985) in key spectral regions to the limiting capability of available facilities. Measurements are underway in the CO line at 115 GHz (Boselli et al. 1995a), in the radio continuum (Niklas et al. 1995), and in the H line (Hippelein et al. 1996). An almost complete set of HI measurements from Arecibo is available (Hoffman et al. 1989 and references therein), and the sample will be measured as part of the central program of the Infrared Space Observatory using the ISOPHOT, ISOCAM and (for spiral galaxies only) LWS instruments.
In this paper we report NIR imaging observations of the majority (94) of the sample obtained at the Calar Alto observatory in 1994, 1995 and 1996. In addition, 8 other galaxies are also included. These measurements provide detailed information on the distribution of the bulk of the stars which dominate the mass in galaxy disks, rather than the younger stars which contribute more to the visible (Aaronson et al. 1979; Whitmore 1984; Gavazzi 1993), and are essentially free from effects of extinction (Peletier & Willner 1992; Boselli & Gavazzi 1994). Apart from aiding the statistical interpretation of data in other spectral ranges by acting as a mass normaliser, the NIR observations reported here will be used in conjunction with H and blue images as a diagnostic of stellar populations within galaxy disks, and to extend earlier work (see Pierce & Tully 1988; Peletier & Willner 1991; Gavazzi et al. 1991) on the IR Tully-Fisher relation for Virgo cluster galaxies to fainter objects. Such aspects will be reported in future communications. Moreover the NIR observations of Virgo galaxies presented in this paper will be integrated with those of other nearby clusters (including A262, Cancer, A1367 and Coma) obtained by Gavazzi et al. (1996a,b) to extend the study of the NIR properties of disk galaxies to a wider luminosity range. The scope of the present paper is to describe the sample selection, observations, and data reduction (Sect. 2) and to present the results in the form of images and derived aperture photometry (Sect. 3). Since observations of almost all the spiral galaxies in the sample have been completed in , the luminosity function of spirals in is given and briefly discussed in Sect. 4 together with some other simply derived quantities.