The Collaborative International Dictionary of English v.0.48:

Astronomical \As`tro*nom"ic*al\ (-[i^]*kal), a. [L.
   astronomicus, Gr. 'astronomiko`s: cf. F. astronomique.]
   Of or pertaining to astronomy; in accordance with the methods
   or principles of astronomy. -- As`tro*nom"ic*al*ly, adv.
   [1913 Webster]

   Astronomical clock. See under Clock.

   Astronomical day. See under Day.

   Astronomical fractions, Astronomical numbers. See under
      Sexagesimal.
      [1913 Webster]