The Spike system (Johnston and Miller 1994, Johnston 1995) was developed by the Space Telescope Science Institute to support planning and scheduling for NASA's Hubble Space Telescope (Miller 1995). Generality was a prime design criterion and Spike has been applied to several scheduling problems including other spacecraft, ground-based observatories and ``job shop'' scheduling problems (Johnston and Minton 1994). Chavan, Johnston, and Albrecht (1995) describe scheduling tools for ESO's Very Large Telescope (VLT), including recent extensions of Spike for long- and short-term ground-based telescope scheduling. In this article I describe the long-term scheduler in more detail and use the Canada-France-Hawaii telescope (CFHT) schedule as an example.
The general problem is to schedule blocks of time (nights and half-nights) obeying the proposer's scientific constraints, the observatory's constraints, and constraints on the overall program such as institutional fractions.