This series is comprised of four logbooks from the Organ Mountain Station of Northwestern University's Dearborn Observatory. The logbooks date between August 22, 1961 and October 26, 1965. Information recorded on logsheets typically includes: name or initials of observer, observation date, identification of object or area observed, times of observation, weather conditions, temperature readings, and telescope and camera readings. Occasional remarks record weather changes and equipment or other problems that arose during observations.