Astro-inertial guidance is a highly specialized term that refers to a particular type of navigation system used in spacecraft and missiles. As such, it may not be easy to find perfect synonyms for this term. However, some alternative words that can be used in certain contexts include celestial navigation, inertial guidance, and star tracking. Other phrases which may refer to the same concept are space navigation and inertial navigation. Additionally, some technical terms found in this field are astro-gyro guidance, star tracker algorithm, and IRU alignment. These synonyms may be useful when discussing various aspects of navigation and guidance systems in the aerospace industry.