A survey of selected areas in the galactic plane with ISOCAM

Abstract

Seven 11.6' × 11.6' fields along the inner Galactic plane were imaged by the Infrared Space Observatory's ISOCAM camera to investigate the large scale properties of the Galaxy. We present results from this GPSURVEY program at wavelengths of 10 and 15 μm as well as some complementary observations from the ISOGAL project at 7 μm. Point source detection is complete to a limiting flux of about 10 mJy. There is generally good agreement between the observed source counts and that predicted by the SKY 5 multiwavelength Galactic structure model. However, some discrepancies were found at certain Galactic longitudes, particularly near the Galactic center. Indications of the nature of the excess sources are inferred from the colour histograms. ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA. This is paper number 5 partially based on data from the ISOGAL project to appear in a refereed journal.