Photogrammetric Determination of Azimuths

Precise azimuth determination to ±1.0 sec of arc over distances of 70 nm to 300 nm is very desirable where electronic survey techniques, such as HIRAN, are used. In January 1962 a series of tests designed to prove the feasibility of a technique of photographic azimuth determinations was conducted by AFCRL. A B-57 aircraft equipped with a flashing stroboscopic light was flown at night at altitudes as high as 35,000 ft between ground camera sites located at Homestead AFB, at Vero Beach, Florida, and at West End, Grand Bahama Island. Six PC-1000 cameras, two located at each site, attempted to photograph the flashing light on the aircraft against a background of stars. The PC-1000 camera has a 1000 mm focal length, and an f/5 lens. Navigation of the aircraft was accomplished by directions from a radar site in the Miami, Florida area. Results of these tests are evaluated from the standpoint of planning this kind of mission, taking into careful consideration haze conditions, star backgrounds, height above horizon for visibility of stars, maximum distances between ground sites and high intensity of the flashing lights.