Project Blue Book Case #2364. On January 28, 1953, a bright object was observed over Corona, California — a community in Riverside County approximately 15 miles north of March Air Force Base, a major SAC installation. March's bombers and tankers were part of the Pacific wing of America's nuclear strike force.
Corona (not to be confused with the famous "Corona" satellite reconnaissance program, which was unrelated) sat in the Inland Empire, surrounded by the rapid suburban development that was transforming Southern California's citrus groves into tract housing. The area's proximity to March AFB meant frequent military overflights.
January 1953 was immediately after the Robertson Panel. The case was classified "Unknown."