The Collaborative International Dictionary of English v.0.48:

Horoscopy \Ho*ros"co*py\, n.
   1. The art or practice of casting horoscopes, or observing
      the disposition of the stars, with a view to prediction
      events.
      [1913 Webster]

   2. Aspect of the stars at the time of a person's birth.
      [1913 Webster]

WordNet (r) 3.0 (2006):

horoscopy
    n 1: the drawing up and interpretation of horoscopes