Star transit

A Star transit is the passage of a star through the eyepiece of an telescope.

The precise observation of star transits is the basis of many methods in Astronomy and in Geodesy. The measurements can be done in different way:
# 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 elektro 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

* Meridian circle
* Passage instrument
* Theodolite
* angular measurement
* accuracy
* precision
* Instrument errors
* Arc seconds
* angular mil

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.