Astronomical clock

a clock indicating or representing the movements of the sun or planets, the phases of the moon, or the sky visible at a given time, used as a means of establishing time or for additional information, as locating celestial bodies or timing their movement.
a clock used for observing the apparent time of the meridian p-ssages of heavenly bodies.
historical examples

the history of the 18th-century borghesi astronomical clock is described here from contemporary source material.
smithsonian inst-tution – united states national museum – bulletin 240 anonymous

this led, some years later, to perfecting an astronomical clock for measuring movements of the stars.
little journeys to the homes of the great – volume 12 elbert hubbard

the astronomical clock is the constant companion of the transit instrument.
letters on astronomy denison olmsted

poynet, bishop of winchester, gave an astronomical clock to the same king.
the privy purse expenses of king henry viii from november mdxxix, to december mdxxxii nicholas harris nicolas

the practical application of this idea he afterwards adopted in the construction of an astronomical clock.
the astronomy of milton’s ‘paradise lost’ thomas orchard

noun
a complex clock showing astronomical phenomena, such as the phases of the moon
any clock showing sidereal time used in observatories