Astronomical Transit

Astronomical Transit

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Astronomers used transit instruments to determine the meridian altitude of a star and, in conjunction with a clock, the time a star crossed the meridian. A “broken” transit has a mirror or right-angle prism that sends the light from the objective to an eyepiece at one end of the horizontal axis. This example came from the U.S. Naval Observatory. The objective is 2.5-inch aperture. The vertical circle is 8.5 inches diameter. The level at the other end of the axis is 8.5 inches long.
Currently not on view
Object Name
Astronomical Transit
Physical Description
brass (overall material)
wood (overall material)
overall: 13 in x 35 in x 30 1/4 in; 33.02 cm x 88.9 cm x 76.835 cm
ID Number
accession number
catalog number
Credit Line
U. S. Naval Observatory
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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