University of Illinois Observatory

901 S. Mathews Ave., Urbana, Illinois



Constructed by the State of Illinois in 1896, the University of Illinois Observatory is significant for its association with the development of the selenium photoelectric cell, which revolutionized the science of astronomical photoelectric photometry (the measurement of celestial magnitudes). This cell was developed by Joel Stebbins (1878-1966), who served as director of the observatory from 1907 to 1922. As a result of Stebbins' work, photoelectric photometry became the standard technique in determining stellar magnitudes. -- National Historic Landmark statement of significance, December 20, 1989

National Register information 

Posted to the National Register of Historic Places on December 20, 1989
Reference number
Areas of significance
Engineering; Education; Science
Level of significance
Evaluation criteria
A - Event; C - Design/Construction; B - Person
Property type
Historic functions
College; Research facility
Current functions
College; Research facility
Period of significance