Principia Astronomical Observatory stands on the campus of Principia College in Elsah, Illinois, where it has served the college since its installation on June 18, 1998. Its telescope was identified as the largest academic telescope in the region. The instrument uses a Ritchey-Chrétien design with a 16-inch mirror and an objective focal length of 4000 mm. Don Loomis, a former chief optician at Kitt Peak National Laboratories, ground and certified the mirror. Optomechanics Research manufactured the telescope, and Dave Harvey of Comsoft Software in Tucson, Arizona, wrote its Telescope Control System software.