We propose to carry out observations of some intermediate redshift
clusters ( z=0.4) with CAM and PHOT. Selected clusters have been
extensively studied by authors of this proposal. Membership has been
derived for all their galaxies. Further, we derived morphology and
spectral energy distribution (SED) from U (or B) band up to I (or K)
band for all cluster galaxies. The role of the dust inside blue,
starburst galaxies and E+A galaxies, both being a large fraction of our
cluster's population, is by far completely unknown.
The overabundance of blue galaxies in clusters is expected since 1978
(Butcher-Oemler effect), however it is well known by now a bluening of
the field galaxy population at the same redshift.
Planned observations will allow us to investigate for the first time
over a very large spectral range:
_the evolutionary properties of each single galaxy inside the clusters,
_the average evolutionary properties for morphological type, as well as
_the effects of mergers, interactions and starbursts
shedding light, in a self-consistent way, both on the evolutionary
properties of the IR luminosity, a good tracer of the star formation
rate, and on the related optical-near-IR SED of these cluster
galaxies. By comparing these results with those of field galaxies
at the same redshift, we could derive statistical information on
the frequency and on the intensity of these phenomena in different
environments.
E+A galaxies are a peculiar class of elliptical cluster galaxies
showing redder colours than those of  field ellipticals.
Following recent suggestions they are post-starburst galaxies. IR data
can dissipate our doubts on their nature since the IR SED is strongly
dependent both on the intensity and on the age of the burst.
Evolutionary properties of normal and starburst galaxies in
intermediate clusters will be investigate.