an astronomical and navigational instrument for gauging the altitude of the Sun and stars

mid-14c., from Old French astrelabe, from Medieval Latin astrolabium, from Greek astrolabos (organon) "star taking (instrument)," from astron "star" (see astro-) + lambanien " [..]

tool used by ancient navigators to determine the position of celestial objects.

Instrument designed to observe the positions and measure the altitude of celestial bodies; used from the 2nd century BCE, until superseded by sextant.

An ancient instrument that allows users to make astronomical observations and calculate from them such information as their precise location on earth, the date and precise time. 

An ancient circular instrument used to observe and calculate the position of celestial bodies.

an instrument that allowed sailors to measure latitude.

The most important instrument used by astronomers and navigators from antiquity through the 16th century. The function of the astrolabe (from the Greek astro, "star"; and labio, & [..]

(n) an early form of sextant

an instrument used to determine the altitude of celestial objects before the introduction of the sextant. The first recorded use by Greek astronomers in around 200 B.C.

A navigational instrument. It consisted of a dial, showing degrees, with an arm (alidade) pivoting through the centre. This arm, had a projection with a small hole on each end, you would line these up [..]

A precursor to the sextant. An old navigational device for checking the altitude of the sun or stars.

A precursor to the sextant. An old navigational device for checking the altitude of the sun or stars.

An ancient instrument for measuring the altitude of the sun, superseded by the quadrant and sextant.

An instrument which measures altitudes of celestial bodies, used for determining an accurate astronomical position, usually while ashore in survey work. Originally, the astrolabe consisted of a disk w [..]