Photosensitive horizon scanner for space vehicle

Claim 1

A POSITION DETERMINING SYSTEM COMPRISING OPTICAL MEANS FOR FORMING AN IMAGE OF AN ILLUMINATED CIRCULAR OBJECT IN A DARK BACKGROUND, PHOTOSENSING MEANS ADJACENT SAID OPTICAL MEANS FOR LINEARLY SCANNING SAID IMAGE OF SAID OBJECT ALONG AT LEAST THREE SPACED LINES EACH EXTENDING THROUGH AN EDGE OF SAID IMAGE OF SAID OBJECT AT A PREDETERMINED SCANNING RATE, DIFFERENTIATOR CIRCUIT MEANS HAVING AN INPUT AND AN OUTPUT, AND COMPUTER MEANS CONNECTED TO SAID OUTPUT OF SAID DIFFERENTIATOR CIRCUIT MEANS; SAID INPUT OF SAID DIFFERENTIATOR CIRCUIT MEANS CONNECTED TO SAID PHOTOSENSING MEANS; SAID PHOTOSENSING MEANS GENERATING A SHARP PULSE WHEN THE ILLUMINATED EDGE OF SAID IMAGE OF SAID OBJECT IS SCANNED; SAID COMPUTER COMPRISING A COORDINATE COMPUTER MEANS FOR TRANSLATING SAID SHARP PULSES OF SAID PHOTOSENSING MEANS INTO COORDINATE INFORMATION WHEREBY THREE COORDINATES OF THE EDGE OF SAID CIRCULAR OBJECT ARE DETERMINED; SAID COORDINATE COMPUTER MEANS BEING OPERABLE TO COMPUTE THE CENTER OF SAID OBJECT FROM SAID THREE COORDINATES.