What do you call an old instrument which was used to measure altitude of stars and planets?

whee

A Sextant http://www.learntonavigate.com/celestial.htm or an Astrolabe "The ancient Greeks learned to make precise instruments, crowned by the ingenious astrolabe. This hand-held device had a moveable arm to measure the angle of a bright star above the horizon — the star's "altitude." Rotating a metal map of stars to match engraved curves, the user could determine time and direction, locate stars in the sky, determine when the sun would rise or set, and make other calculations. Astrolabes reached their standard configuration by the fourth century, having been first developed in the first or second century near the Egyptian city of Alexandria." http://www.aip.org/history/cosmology/tools/tools-nakedeyes.htm Mar 04 08, 8:18 AM