Scheduling

Overview

In this context "Scheduling" is an operation on a time ordered list of scans to determine the actual times in which each scan is to be executed and to do a validity check for such problems as incomplete information (e.g. no position given), invalid requests (e.g. source below horizion or frequency out of range) or looking for other potential problems (e.g. antennas shadowing each other).

VLA Details

As the VLA is the only current implementation its practices should be followed, wherever possible, in other implementations. The VLA.VLAScan member VLA.VLATimeF contains a boolean member scheduled which indicates if the scan has been "scheduled". The scheduler (Telescope function Schedule ) loops through the Observe Scan List looking for the first unscheduled Scan and the "schedules" this and all following Scans. The start time of a scan is the end time of the preceeding scan, or, the start time of the observations for the first Scan in the list.

There are several ways for the user to specify the length of a Scan; either an explicit stop time, a duration (total time), or a dwell time (time actually on source) can be specified. The scheduling process must compute the move time from the previous source and then determine the actual Start, Stop and Begin (when on source) times. Detailed values for LO settings must also be determined if not explicitly provided (this is by far for most involved part of this process).