Hercules - Gyro-based, real-time geolocation for an astronaut camera

A new latitude-longitude locator called Hercules is being developed for attachment to a hand-held astronaut camera. A top level description is made of the Hercules hardware, operational concept, and geolocation process. Detailed algorithms are provided for the high-speed propagation of the Euler parameter from the angle measurements of the ring laser gyro, for earth orientation, for the latitude-longitude solution using a noniterative slant range, for the apparent place of stars, and for the determination of true inertial attitude from two star sightings.