|accessory: used here to refer to any associated parts of an instrument such as tripod base and legs.
|age of the moon: number of days that have passed since the previous new moon.
|alidade: straight rule with sights. An alidade could be used for surveying with a plane table but it also appears in a different form as part of an astrolabe.
|almucantars: lines of equal altitude on a projection of the heavens based on the local horizon.
|altazimuth theodolite: theodolite for measuring altitude and azimuth simultaneously, see article on the theodolite.