  Telescope arrays are receiving increasing attention due to their promise of
higher resource utilization, greater sky survey area, and higher frequency of
full space-time monitoring than single telescopes. Compared with the ordinary
coordinated operation of several telescopes, the new astronomical observation
mode has an order of magnitude difference in the number of telescopes. It
requires efficient coordinated observation by large-domain telescopes
distributed at different sites. Coherent modeling of various abstract
environmental constraints is essential for responding to multiple complex
science goals. Also, due to competing science priorities and field visibility,
how the telescope arrays are scheduled for observations can significantly
affect observation efficiency. This paper proposes a multilevel scheduling
model oriented toward the problem of telescope-array scheduling for time-domain
surveys. A flexible framework is developed with basic functionality
encapsulated in software components implemented on hierarchical architectures.
An optimization metric is proposed to self-consistently weight contributions
from time-varying observation conditions to maintain uniform coverage and
efficient time utilization from a global perspective. The performance of the
scheduler is evaluated through simulated instances. The experimental results
show that our scheduling framework performs correctly and provides acceptable
solutions considering the percentage of time allocation efficiency and sky
coverage uniformity in a feasible amount of time. Using a generic version of
the telescope-array scheduling framework, we also demonstrate its scalability
and its potential to be applied to other astronomical applications.
