Millimetre emission from extragalactic objects II. Luminosities, spectra and contribution to the microwave background.

Complete samples of various types of extragalactic sources have been compiled and observed at 1-millimeter wavelength. A radio-millimeter-infrared color-color diagram and the spectra of individual sources are used tentatively to delineate these types into two classes, according to whether their emission appears to be thermal (dust) or synchrotron in the submillimeter region of the spectrum. A crude luminosity function is obtained, and the total discrete-source contribution to the background at 1 mm is estimated.