First ISOCAM images of the Milky Way

. ISOGAL is a 15 ¯m ISOCAM survey of ¸ 12 deg 2 in the Galactic Plane interior to j`j = 45 ffi . In combination with IJK data from the near-infrared southern sky survey DENIS, the ISO images allow the first detailed study of stellar populations throughout the inner Galaxy. We present preliminary results from a test observation at ` = \Gamma45 ffi with 6" pixels and completeness limit 8 mJy. Of the ¸ 3000 sources deg \Gamma2 detected, about half are KM giants, seen through extinction of up to A v ¸ 30, while most of the remainder are probably dusty young stars. Although away from bright IRAS regions, the field displays spectacular emission features, and, unexpectedly, a number of regions which are optically thick at 15 ¯m. The dark regions are presumably dense filaments with A v ? 25. Key words: The Galaxy: stellar content -- Interstellar medium: general -- Interstellar medium: dust, extinction -- Infrared: galaxies -- Infrared: stars Send offprint requests to: M. P'erault, m..