In Japan, photoelectric observations of occultations were made for the first time in 1951.

For about ten years after that, observations were made partly for geodetic purposes in order to determine the position of Japan with reference to islands in the Pacific, Phillippine and Taiwan.

The geodetic datum of Japan, which is currently adopted, suffers seriously from the vertical deflection. The amount of this deflection is supposed to be about 10″ in latitude and 20″ in longitude.

This project of occultation geodesy was, however, not so successful, because of the following two reasons: (1) Poor efficiency of data acquisition due to weather. We need good weather at two stations; the distance between them is usually over 1000 km. (2) Difficulty of correction for the Moon’s limb. For geodetic purposes, the atlas of the Moon’s limb by Dr Watts is still insufficient.

Therefore, the project of occultation geodesy was replaced by satellite geodesy.