Markowitz Camera

an astronomical instrument for positional photographic observations of the moon—that is, determination of the coordinates of the center of its visible disk relative to stars. The Markowitz camera was invented by the American astronomer W. Markowitz in the 1950’s. It makes it possible to overcome the difficulties in lunar observations caused by the moon’s great brightness and rapid motion relative to the stars.

The Markowitz camera is equipped with an attachment (a Markowitz cartridge), which can be used in other telescopes. In the Markowitz cartridge, light from the moon passes through a dense filter in the form of a plane-parallel plate before striking the photographic emulsion. The filter is driven by a gear and rotates about an axis parallel to the plane of the photographic plate and perpendicular to the direction in which the moon moves among the stars. The small filter absorbs only the light of the moon, thus equalizing the exposure time for the moon and stars. As it rotates, the plane-parallel plate shifts the image of the moon and thereby compensates for the motion of the moon’s image relative to the stars. The results are clear images of the moon and the stars.

The Markowitz camera is not widely used, although the Markowitz cartridge is commonly used in conjunction with a cartridge constructed by the Soviet astronomer A. A. Mikhailov for photographing the moon and Venus. The accuracy of photographs obtained along the equatorial coordinates of the moon is characterized by a standard deviation of ±0.3-0.4”. Observations with a Markowitz camera are used for determining ephemeris time, improving the theory of the moon’s motion, refining the orientation of the fundamental coordinate system, and studying the figure of the earth.