Denver, ColoradoSeptember 1952

On September 24, 1952, Technical Sergeant Billy Ross Hughes saw five or six circular objects wheeling through the sky over Aurora, Colorado, just north of Stapleton Airport. The time was 1525 (3:25 p.m.), and Hughes was standing in the business district of Aurora, about eight miles east of Denver. He had just stepped out of a drugstore when he glanced up and spotted the objects moving in a circle about five or six times larger than their own diameter. Hughes was looking at them at an angle of roughly 30 degrees above the horizon.

The objects appeared very bright and white, with no trails, exhaust, or sound. Hughes moved to stand in the shade of a building so his eyes could adjust to the bright sky, and he continued watching. As two C-47 cargo aircraft passed through his line of sight at an estimated altitude of 2,500 feet, Hughes noted that the mysterious objects were flying much higher. At one point, one object dipped down so sharply that it appeared four times as large, then disappeared to the southwest. When Hughes's attention followed that object, the other five suddenly vanished as well. He searched the sky for seven minutes but could not find them again. The entire sighting lasted five to six minutes. The weather that afternoon was clear to partly cloudy, with light winds and excellent visibility.

The Air Force investigated the report and found no explanation for what Hughes had seen. Weather balloons released in the area were ruled out. The file notes that the Air Force had "no op" (no opinion) as to what the objects were. No photographs or physical evidence was recovered, and no unusual activity at nearby Stapleton Airport could account for the sighting. A letter follow-up was planned. The case was formally rated by the Air Force as unidentified.

The full case file is reproduced below as held by the National Archives, comprising 9 pages of scanned documents.