OBSERVATIONS OF THE GALACTIC CENTRE WITH ISO

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 groundbased observations ranging from 12001.2 micron, thus providing detailed information either side of the transition from stardominated to dustdominated emission, which in the galactic centre occurs between virgul57 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 groundbased nir images we will determine continuum spectra in the wavelength range 1.216 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 highresolution 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. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]