The Collaborative International Dictionary of English v.0.48:

Sexagesimal \Sex`a*ges"i*mal\, a. [Cf. F. sexag['e]simal.]
   Pertaining to, or founded on, the number sixty.
   [1913 Webster]

   Sexagesimal fractions or Sexagesimal numbers (Arith. &
      Alg.), those fractions whose denominators are some power
      of sixty; as, 1/60, 1/3600, 1/216000; -- called also
      astronomical fractions, because formerly there were no
      others used in astronomical calculations.

   Sexagesimal arithmetic, or Sexagenary arithmetic, the
      method of computing by the sexagenary scale, or by
      sixties.

   Sexagesimal scale (Math.), the sexagenary scale.
      [1913 Webster]

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]