The Palomar wedge sensitometer

A simple sensitometer for use in providing intensity calibration on photographic plates, which has been in use for many years at Palomar Observatory, is described. External comparison between reduced photographic aperture magnitudes for galaxies and CCD photometry for the same objects shows that use of this device results in proper intensity scales. The intensity scale produced using this instrument also agrees well with that produced by the KPNO spot sensitometers.