Photographed round luminous object — Datil, New Mexico (Feb 24–25 1950, Sighting 175)

On 24–25 February 1950, Cpl. Lertis E. Stanfield of Holloman AFB photographed an unknown aerial object at Datil, New Mexico (Sighting 175 in the 17th District OSI summary). Dr. Lincoln LaPaz analyzed the photograph and concluded: (a) the object's angular diameter was approximately 1/4 degree, and (b) its angular velocity was greater than 1/2 degree per minute. LaPaz formally ruled out the moon (angular diameter too small), Venus or any other planet (angular diameter too large), and a bright fixed star slightly out of focus (observed angular motion rate is double that attributable to Earth's diurnal rotation).

“"The angular diameter of the perfectly round luminous object Stanfield observed was approximately 1/4 of a degree. The angular velocity of the object in the sky was greater than half a degree per minute. Dr. LaPaz stated that on the basis of the results (a) and (b) above, the object seen by Stanfield was not the moon … not Venus or any other planet … and it was not a bright fixed star slightly out of focus."”

Photograph exists (referenced in the document as Photo of Sighting No. 175, included as Inclosure 2 in the May 25, 1950 summary letter). Dr. LaPaz's analysis is methodologically sound, ruling out known natural and astronomical explanations through angular measurement. Single ground observer; photograph not reproduced in the OCR text. Location of Datil, NM is a real place and is geolocatable with confidence. This is one of the most analytically rigorous individual incidents in the file.