Figure 1-11. Arc Distance Determination by Star Occultation
(2) The moon-position camera method involves photographing the moon against a background
of stars. The camera eliminates the problem of the great difference in the motion of the moon and the
stars. Important geodetic data can be obtained from plates exposed at well-distributed stations. During
the first international geophysical year (1 July 1957-31 December 1958), observations were made at
several stations distributed throughout the world. The observed data is still being processed.
(3) The observation and tracking of artificial earth satellites shows the most promise for
obtaining valuable geodetic data in the future. After the satellite is in orbit around the earth, it is
possible to track it optically using specially constructed ballistic cameras or electronically by using the
sequential collation of ranges (SECOR) system.
(a) For optical tracking, the satellite is photographed from known and unknown observation
points. The satellite, which is designed specifically for optical