Optical sensors are basically telescopes, gathering light reflected off an object in space. Cloud cover, fog, atmospheric pollution, light glow from cities or a full moon degrade or prevent observations. The size of the object to be tracked and its distance from Earth are also limiting factors. Baker Nunn Camera b. The BakerNunn camera is a large telescope with a camera attached.
Imagery is recorded on film.
Two to four hours are required for on site film processing and image analysis after which data is transmitted to the Space Surveillance Center. The position a space object in the photo is determined by analyzing the star background. Sensor data are stored on magnetic media for analysis locally or the data are transmitted in near real time to the Space Surveillance Center for analysis, if required. The system can image objects in space with an altitude of more than 22,000 miles. The sensors only operate at night.