Parallactic instrument of Kapteyn

The parallactic instrument of Kapteyn is a measuring instrument created by the Dutch astronomer Jacobus Kapteyn around 1886. Using this instrument, Kapteyn analyzed over 1,700 glass plate photos of stars seen from the southern hemisphere. This research contributed to the Cape Photographic Durchmusterung, a star catalogue containing 454,875 entries. Together with the measurements of stars seen from the northern hemisphere (the Bonner Durchmusterung) the measurements of Kapteyn formed a complete star catalogue with a scope and accuracy that was impressive for its time.

The instrument is currently located in the collection of the University Museum of Groningen.