{{Short description|Passage of a star across the field of view of a telescope eyepiece}} {{For|the transit agency in Texas|STAR Transit}} {{For|the transit agency in Virginia|STAR Transit (Virginia)}}
{{No footnotes|date=April 2026}} thumb|right|350px|Star transits (Reticle 2°, magnif. ~10, two stars passing the vertical thread). Timing accuracy may be ±0,5 s.
A '''star transit''' is the passage of a star across the field of view of a telescope eyepiece.
The precise observation of star transits is the basis of many methods in astronomy and in geodesy. The measurements can be done in different ways:
# visually (mostly up to 1990): accuracy 0,1" to 2" (depending on the instrument); timing with digital clocks about 0,05–0,2 seconds; # by CCD and other electro-optical sensors: as above, time often better; # semi automatic instruments: photography or "impersonal micrometer", ca. 2 times better than No. 1; # by scanning methods: astrometry satellites like Hipparcos about 0,01".
==See also== * Accuracy and precision * Instrument error * Meridian circle * Minute and second of arc * Theodolite * Transit instrument
==Literature== * Karl Ramsayer, 1969: ''Geodätische Astronomie'', Vol.2a of Handbuch der Vermessungskunde, 900 p., J.B. Metzler-Verlag Stuttgart. * Ivan I. Mueller, 1969: Spherical and Practical Astronomy as applied to Geodesy, 610 p., Fred.Ungar publ., USA * IAU Coll.48: ''Modern Astrometry'', Egermann, University Vienna.
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Category:Astrometry
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