Elginfield Observatory, Astronomical observatory in Middlesex Centre, Canada

Elginfield Observatory is a closed astronomical observatory in Middlesex Centre, Ontario, about 25 km north of London. It was owned and operated by the University of Western Ontario and opened in 1969. Its main instrument is a 1.2 m (47 in) Ritchey–Chrétien telescope built by Boller and Chivens, used for spectroscopy and photometry and configurable at the Cassegrain, Nasmyth and Coudé foci.

The observatory was established in 1969 by the University of Western Ontario and operated research projects for four decades to advance understanding of celestial objects. The facility ceased operations in 2010, marking the end of an era of ground-based astronomical research in the region.

The observatory carried the IAU number 440, the identifier under which its observations were catalogued internationally. Its research programme tracked the changing size of Cepheid variable stars, estimated out-gassing from minor planets and searched for large Perseid meteoroids.

The observatory stands in Middlesex Centre, about 25 km north of London, Ontario, on a rural site chosen for darker skies. It closed at the end of 2010 and is not open to visitors, so the building and its 1.2 m telescope can only be seen from outside. The surrounding roads are the only public access.

The telescope could be adjusted to three different optical positions, allowing scientists to use different instruments simultaneously or in succession. This flexibility was an unusual feature that let the facility conduct various types of sky studies.