Telescope Network Scheduling - Rationale and Formalisms

Scheduling of university and institutional telescopes is typically performed manually, and astronomers are used to interacting with a human to explain their requirements for resources and time. Las Cumbres Observatory Global Telescope (LCOGT) is deploying a worldwide network of robotic telescopes. At LCOGT manual scheduling is infeasible due to: 1) the number of resources and observations that must be scheduled, 2) the scheduling-time dependencies that arise when concurrent or consecutive access to telescopes is required, and 3) the need to rapidly re-calculate the schedule to accommodate near-real-time requests from high priority observing programmes (e.g. transient followup programmes), and changing resource availability due to weather and other reasons. In this paper we develop a formalism capable of expressing the complex requirements and preferences of astronomers concerning resource and time allocation on a telescope network, and formulate the offline telescope network scheduling problem as the problem of choosing and scheduling (i.e. assigning concrete start and end times to) a maximum priority, non-overlapping subset of an input list of requests.