Josef Allen Hynek (May 1, 1910 – April 27, 1986) was an American astronomer, professor, and ufologist. He is perhaps best remembered for his UFO research. Hynek acted as scientific advisor to UFO studies undertaken by the U.S. Air Force under three projects: Project Sign (1947–1949), Project Grudge (1949–1951) and Project Blue Book (1952–1969). In later years, he conducted his own independent UFO research, developing the "Close Encounter" classification system. He was among the first people to conduct scientific analysis of reports and especially of trace evidence purportedly left by UFOs.