Abstract: A system and method for star tracking includes: capturing an image of stars; detecting and selecting visible stars from the captured image; extracting features from the selected stars by forming a convex hull from the selected stars to generate a spherical polygon; computing the area and higher order moments of the spherical polygon; and pattern matching the extracted feature against a database of star catalog. The pattern matching includes matching the area of the spherical polygon to a plurality of polygon areas stored in the database and when the number of the matching candidates is more than one, matching a next extracted higher order moment with a respective higher order moment in the database, and repeating said matching of the next extracted higher order moment until the number of the matching candidates is equal to one.

Abstract: A system and method for star tracking includes: capturing an image of stars; detecting and selecting visible stars from the captured image; extracting features from the selected stars by forming a convex hull from the selected stars to generate a spherical polygon; computing the area and higher order moments of the spherical polygon; and pattern matching the extracted feature against a database of star catalog. The pattern matching includes matching the area of the spherical polygon to a plurality of polygon areas stored in the database and when the number of the matching candidates is more than one, matching a next extracted higher order moment with a respective higher order moment in the database, and repeating said matching of the next extracted higher order moment until the number of the matching candidates is equal to one.

Abstract: A target intercept system for guiding an interceptor to a target using passive ranging includes an EO/IR sensor that provides target azimuth and elevation angles, target irradiance, target area and target length. A dual Kalman Filter architecture is implemented where, prior to a target image becoming resolved, i.e., prior to endgame, a first Kalman Filter provides guidance as a function of target azimuth and elevation angles and target irradiance measurements. After the target image becomes resolved, i.e., at endgame, a second Kalman Filter provides guidance as a function of target azimuth and elevation angles, target area and, optionally, target length, instead. The dual Kalman Filter approach improves the estimates of time-to-go by optimizing the on-board EO/IR sensor measurements at the optimal times.

Abstract: A target intercept system for guiding an interceptor to a target using passive ranging includes an EO/IR sensor that provides target azimuth and elevation angles, target irradiance, target area and target length. A dual Kalman Filter architecture is implemented where, prior to a target image becoming resolved, i.e., prior to endgame, a first Kalman Filter provides guidance as a function of target azimuth and elevation angles and target irradiance measurements. After the target image becomes resolved, i.e., at endgame, a second Kalman Filter provides guidance as a function of target azimuth and elevation angles, target area and, optionally, target length, instead. The dual Kalman Filter approach improves the estimates of time-to-go by optimizing the on-board EO/IR sensor measurements at the optimal times.