Scheduling with PC-SCHED

This is a DOS program that will run adequately on a 386 processor (although speed is much improved by using a 486 or pentium processor). It was written by Dave Schultz and Alan Rogers at Haystack observatory. The latest version of PC-SCHED (v4.0) is available via anonymous ftp from both JIVE and Haystack. The JIVE release contains modifications to the original Haystack release (specifically to codes.sch and antenna.sch) and should be used for all EVN experiments.

Key input files for PC-SCHED are:

• The antenna.sch - station catalog. This file may be edited to include new telescopes, or improve exisiting station coordinates.
• The source.sch - source catalog. This file may be edited to include new sources, or improve exisiting source coordinates.
• The codes.sch - receiver set-up file, and contains frequency code information. Experienced users may modify these set-ups.
• The procs.sch - station specific procedures.

The output files are:

• The drudge file (or .DRG) - This is the basic experiment schedule from which station specific schedules are created.
• The cover letter - a plain text file listing useful experiment specific information. It is appended by PC-SCHED to both the drudge and listing files.
• The snap file (*SNA.)- contains the snap commands to control the VLBI terminal during observation, and one file is produced for each station.
• The procedure file (*PRC.) - procedures called from the snap file. It will also contains station specific procedures.
• The listing file (*LST.) - scan-by-scan listing of the experiment, which provides an easy to follow guide for telescope operators during the experiment.

Useful hints for PC-SCHED

• As the drudge file is saved, the cover letter is automatically created. Before creating snap files etc, edit the cover letter to contain the information you require, as this will save a lot of editing later. This time when you save the drudge file, the edited cover letter is appended to it and to the listing file.
• The default time allowed for tape changes is $\sim$6-7 min. To allow for longer time for tape changes then first finish the entire schedule and optimise it. Then step through the schedule to the tape changes and manually insert the time required and with careful use of the optimisation flag, re-optimise the schedule without allowing PC-SCHED to change the manual time gaps you have inserted.
• You must consider the tape capacity you have, and the length of `tape passes' within your experiment. A VLBI tape consists of many separate tracks of data only a small fraction of which are written to at a time. The number of tracks written during a `tape pass', and hence the number of tape passes before a tape is filled depends on the mode of recording. Note that if you have more than one tape available it is vital that you leave 6-10 minute gaps at each EVN station to ensure that the tape change occurs smoothly.
• Now begin entering scans into the PC-SCHED program. Each scan has a duration, a source observed, a set of antennas observing that source and finally a code indicating which observing mode is being used. Look at the tutorial in the PC-SCHED guide to see how to enter scans. It is best to schedule in units of the tape pass length (13 minutes (780s) for normal speed experiments and 6.5 minutes (390s) for double speed experiments. For instance you could observe a group of sources spending 1 pass (i.e. 13 minutes for normal speed experiments) on each. You can also split a pass between several scans on different sources (i.e. spend 3 minutes on one source and 10 minutes on another). You should not however try to schedule a set of scans which do not fit neatly into tape passes (i.e. 8 minutes on one source and 8 minutes on another is a bad choice).
• For continuum experiments the setup codes will be one of the standard modes (use the view menu to examine receiver setups within your PC-SCHED), the first letter indicates the observing band (L- 18cm, C-6cm, X-3.6cm, K-1.3cm, Q-0.7cm) while the second indicates the observing mode (A-E), a upper case letter indicates standard speed while lower case indicates dual polarisation or double speed recording.
• For spectral line experiments you will have to edit CODES.SCH to create your own special setup files. A spectral line guide that pays close attention to MkIII formats and PC-SCHED might once have been useful, but probably not any more.
• Appropriate antenna codes can be found by selecting `telescope list' within the PC-SCHED View menu.