Sproul Observatory

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Sproul Observatory
Organization Swarthmore College
Location Swarthmore, PA
Coordinates 39°54′13″N 75°21′19″W / 39.90361°N 75.35528°W / 39.90361; -75.35528
Altitude 60 meters (200 feet)
Website www.cs.swarthmore.edu/program/history/sproul.html
Sproul Telescope 24 in (61 cm) refractor telescope

Sproul Observatory is an astronomical observatory owned and operated by Swarthmore College. It is located in Swarthmore, Pennsylvania, United States,[1] and is named after William Cameron Sproul, the 27th Governor of Pennsylvania, who graduated from Swarthmore in 1891.


An open house is offered on the second Tuesday of the month by the Physics and Astronomy department [1]


  1. John A. Miller (1923–1938)
  2. Peter van de Kamp (1937–1972)
  3. Wulff-Dieter Heintz (1973–1982)
  4. Sarah L. Lippincott (1982–)

Planetary discovery controversies[edit]

Under the direction of Peter van de Kamp this observatory made numerous claims of planetary systems and discoveries based on astrometry using the photographic plates made with the 24 in (61 cm) refractor telescope. These plates were found to have a systematic error that was misinterpreted as the effect of a planetary system on the parent star. This error was identified as early as 1973[2] and confirmed by the observatory in the 1980s.[3]

See also[edit]


  1. ^ a b "Astronomy at Swarthmore College". Retrieved 2008-04-12. 
  2. ^ John L. Hershey (June 1973). "Astrometric analysis of the field of AC +65 6955 from plates taken with the Sproul 24-inch refractor". Astronomical Journal. 78 (5): 421–425. Bibcode:1973AJ.....78..421H. doi:10.1086/111436. 
  3. ^ Lippincott, S. L. (1982). "A Mistake in the Wobble". Science News. 122: 51. Bibcode:1982SciN..122...51L. doi:10.2307/3967230. 

External links[edit]

Coordinates: Satellite 39°54′11″N 75°21′19″W / 39.90308°N 75.3553°W / 39.90308; -75.3553