We propose observations in two CAM filters (LW2 and LW3) of the deep
IRAS survey sample (IDS; Hacking et al 1987), complete for S(60micron)>
50mJy over an area of 6.25 sq. deg., plus measurements with the PHT
C100 array of the sources lacking reliable IRAS 100micron fluxes.
These observations will:
i) provide essential complementary information to the deep surveys to
be carried out in the same CAM filters within the Guaranteed Time
programme, allowing a direct estimate of the local luminosity function
of galaxies in the 2 wavebands, almost doubling the range in logS over
which galaxy counts are estimated (at least in the LW2 band), and
providing a direct link to the IRAS counts;
ii) allow, together with IRAS data, a systematic study of the broadband
spectral properties of a complete, far-IR selected sample, covering a
particularly interesting redshift range, extending up to, at least,
z~0.3, where optical and sub-mJy radio surveys indicate a significant
excess of faint blue galaxies (the IDS sample has constituted, so far,
the observational basis on which studies of far-IR evolution of
galaxies rely). Multifrequency measurements in the far-IR are essential
to classify the sources (some models imply that a few sources may be
highly obscured z~1 galaxies, difficult to identify optically, but
with characteristic far-IR colours), to single out "hot" objects,
possibly hiding obscured AGN's, to get insight into the abundance and
physical conditions of dust, to determine bolometric luminosities.
The total observing time (including all overheads) is 27.4 hours, of
which 20.75 hours correspond to top priority observations.