Balloon-borne infrared telescope for absolute surface photometry of the night sky.

A dry ice cooled 15-cm ir telescope was used on board the balloon-borne gondola THISBE for absolute surface photometry of the Milky Way, the zodiacal light, and the airglow in the PbS wavelength region. The mechanical, optical, electronical, and thermal design of the instrument is described. The efficiency of the baffle system for suppression of stray light from earth and balloon is discussed in detail. Recent airglow measurements are presented.