We propose ISO observations with CAM at 4.8 and 16 micron and with PHOT
at 25, 60 and 100 micron, as a continuation of the GT programs PGMGALC and
PGMGALC2 of PMEZGER. These proposed observations are meshed with ground-based
observations ranging from 1200-1.2 micron, thus providing detailed information
either side of the transition from star-dominated to dust-dominated emission,
which in the Galactic Centre occurs between ~5-7 micron. Specifically, we
propose to perform large scale mosaicing of the whole Sgr A and Bridge region,
to image dust emission and the stellar light distribution on a range of scales,
to pursue the following scientific objectives:
i) with CAM mosaic images combined with our ground-based NIR images we will
determine continuum spectra in the wavelength range 1.2-16 micron with
relatively high angular resolution. This will allow the distribution of stars
and dust to be disentangled.
ii) Comparison of hot dust emission at 16 micron in the direction of Galactic
Centre GMCs with our high-resolution mm/submm images of dust emission will
yield information about the very early stages of massive star formation.
iii) Although the 4.8 micron emission is expected to be primarily of stellar
origin part of it may also trace emission from very small refractory grains
which may be overabundant in regions of shocked gas
iv) Uexpectedly the Radio Arc and specifically the environment of the
Quintuplet massive star cluster has found to be one of the strongest sources
at 4.8 micron. Its nature and interaction with the neighboring molecular cloud
shall be investigated using CAM images at 4.8 and 16 micron and with PHOT
spectrophotometric imaging between 2.5 and 12 micron and at 25, 60 and 100
microns.