Project 10073 Record Card — Hanna City AFS, Illinois, 20 April 1961

This document contains a Project 10073 record card and associated correspondence regarding a radar-only sighting of an unidentified object near Hanna City AFS, Illinois, on April 20, 1961. The object was detected at an altitude of 97,000 feet on a bearing of 045 degrees. It was tracked for one hour and four minutes, during which it performed a slow descent on a heading of 045 degrees before disappearing from radar at 10,000 feet. The radar operators, A/3C Richard Lhitmer and A/1C William L. Maule II, were noted as being highly competent. The report highlights that the object had a small radar reflecting surface, as slight antenna adjustments caused it to disappear from the display. Meteorological conditions in the area were severe, with heavy winds, rain showers, and thunderstorms forecasted, which were considered relevant to the object's movement and drift. Following the initial report, the Aerospace Technical Intelligence Center (ATIC) requested an analysis of the data. The subsequent evaluation by AFCIN-4E1 concluded that the object was almost certainly a balloon. The analysts reasoned that the observed speed, rate of descent, and the object's size were consistent with a balloon. They further suggested that the 'heavy appearance' of the target on radar was likely due to either low inflation of the balloon or an unusually heavy instrument payload. The documentation includes the original record card, the teletype message (TWX) reporting the incident, and the internal memorandum confirming the final assessment.