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vol.05

Floating Photographic Zenith Telescope (FZT)

In 1939, a floating zenith telescope was delivered to the Mizusawa Latitude Observatory (the current Mizusawa VLBI Observatory, National Astronomical Observatory of Japan). This instrument measures the “wobble” of Earth’s axis by observing the variation in latitude, while maintaining the rotational axis in equilibrium with the telescope bearing floating in a donut-shaped trough filled with mercury. This telescope was in operation for over 46 years, from delivery till 1985. Nikon astronomical observation equipment has contributed to the growth of Japanese astronomical studies to date through their advanced performance and quality.

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