Groombridge Transit Circle

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Groombridge transit circle

Groombridge Transit Circle was a meridian transit circle made by Edward Troughton for Stephen Groombridge in 1806, which Groombridge used to compile data for the star catalogue, Catalogue of Circumpolar Stars.[1] The advantage of a transit circle over a mural circle (which can measure polar distances) is that it allows measuring right ascension and declination at the same time.[2]

It had an aperture of 3.5 inches and a 5-foot focal length, mounted inside two 4 foot circles on stone piers.[2] Groombridge used the instrument to determine the positions of over 4000 circumpolar stars.[2]

It was eventually bought by James South, and it remained at his observatory at Kensington until 1870.[2]

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  1. ^ Groombridge Transit Circle, 1820. -- Science and Society Picture Library
  2. ^ a b c d King, Henry C., (1955/2003). The History of the Telescope. Cambridge, Massachusetts: Sky Publishing Corporation. Retrieved from Google Books in 2010: The History of the Telescope, by Henry C. King, page 234-6

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