Statistical Sample of Late-Type Galaxies from the VIRGO Cluster Part 4

scientific abstract we propose to study a complete volumelimited unbiased sample of 118 spiral, irregular and dwarf galaxies from the virgo cluster in the 40 220 micron spectral range with isophot. the completeness limit of bt 18 magnitude corresponds to the maximum (confusion limited) depth the instrument can achieve, allowing a complete dynamic range in starformation activity to be measured. in parallel, wherever instrument sensitivity permits, we propose a degree of spectrophotometric resolution which by far exceeds that of iras, to provide a basis for distinguishing between dust components of different temperatures and grain size distributions in the galaxian interstellar media. these fir observations will furthermore spatially resolve the central region from the disk for the giant spirals with diameters exceeding a few arcminutes. this should allow a distinction between fir activity in the centres and the disks for about half the galaxies in the sample. using lws, we further propose to survey a subsample of 50 spiral galaxies with integrated blue magnitudes bt < 14.5 for emission in the cii 158 micron fine structure line. observation summary it is proposed to make the fir continuum measurements at diffractionlimited angular resolutions with the phtc200 array in the c120, c160 and c200 filters, and with the c100 array in the c60, c70 and c100 filters. these filters provide the widest spectral range with an even spectral sampling. the use of the c60 and c100 micron filters will facilitate a cross calibration with the iras all sky survey. irregular and dwarf galaxies will only be observed in the wideband c60, c100 and c160 filters. photometry for the fainter targets will be made using the pht22 aot with the focal plane chopper operating in it.s triangular waveform mode. this should enable us to reach the confusion limit due to foreground cirrus of a few mjy rms at 100 micron, sufficien truncat [truncated!, Please see actual data for full text]