We propose to utilize the far-IR capability of ISOPHOT to measure at
120 and 200 microns selected areas near the galactic plane. The ISO
fine-pointing raster scan mode is used to get both accurate surface
brightnesses as well as far-IR colour distributions over selected
areas of ca. 4.5 degrees. The colour index 120 vs. 200 microns is an
important indicator of very cold dust emission. Our aim is especially
to detect small very cold dust clouds suspected to be abundant in the
outer part of our Galaxy. Such clouds would have escaped detection by
IRAS and COBE because of these instruments had limitations in
wavelength coverage or spatial resolution.