Mapping with the LWS of the two central dense cores of the Serpens
molecular cloud is proposed. One of the cores is currently forming a
cluster of low to intermediate mass stars at very high efficiency,
whereas the other one appears relatively inactive and may be in an
earlier phase of stellar formation. Full grating scans with the LWS
offer the opportunity to study simultaneously the physical state of the
gas and the dust and to unvey possible differences between the cores.

The proposed programme is aimed at a complete and homogeneous ISO data
base for a number of star forming regions. We seek to complement CAM
and PHOT mapping observations in the Guaranteed and Open Time by the
respective instrument teams.