The APF Scheduler currently follows the steps below. Items in bold are part of the Target Specification.
The scheduler has three pieces that determine the ranks or priorities of a target
Grade and fraction of the night are allocated by the APF TAC. The grade is the most important and the internal priority can never be high enough to move a target from one grade to another. Within a given grade, internal priorities are used to determine which star has the highest priority.
Programs are allocated fractions of a night. The program fraction is proportional to the total allocation of hours for 1000 hour semester. The minimum fraction is set to 10%, however.
The fraction used by a program is only computed after the most recent observation.Therefore, a program is turned off when the fraction is exceeded. A small program that needs, for example, a one hour observations will also be able to conduct those observations even if the nightly fraction would fall below that. Once the observation is made, however, the program cannot take any more data for that night.