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The NCCS must provide at least the same scheduling capabilities as the
A description of the present scheduler is as follows :
The present system makes a distinction between the master observing
program (MOP) and routine observing programs (ROP).
The philosophy of the present system (as implemented by SHPRM/SCHDL on the
HP 1000s) is that the telescope is managed as a global resource.
The current program has control of the telescope until such time
as it decides to release it.
At this time if the scheduler has work to do (this has been calculated previously
by looking at the input parameters) it wakes up and schedules the program
which is supposed to run.
The program which is supposed to run is calculated based on the present
sidereal time, the requested source's coordinates and the mode of routine
The following modes are supported:
Every program has to specify the observing frequency, radiometer
mode (if continuum) and source name/coordinates.
5 optional parameters can be specified to the scheduler
to specify anything else the observing
program wants to use the optional parameters for.
- calculated hour angle (maximum of 13 observations per day),
- at a given hour angle (maximum of 7 observations per day),
- immediate scheduling (after 1 minute).
Once a ROP has gained control of the telescope it keeps it until such time
as it decides to release the telescope back to the scheduler.
The list of ROPs to be scheduled and their parameters are kept in a
file which is read by the scheduler each time it starts up.
This ensures that the list of scheduled programs is maintained over
system crashes and that it can be modified during runs and the
scheduler will take the modifications into account.
The NCCS must offer all the above options.
Additional options which are desirable are :
- The ability for
the NCCS scheduler to interrupt an observing program and if necessary
suspend it and schedule a new program.
The notion of priorities of observing programs will have to be introduced in
order to do this.
Programs with a higher priority will have precedence over programs
with a lower priority.
Programs should only be interrupted at the end of an observation.
The definition of what is an observation will depend on the kind
of observation i.e. continuum, spectral lines, mapping, pulsars.
Priorities will be distributed by the operations manager but it
should be possible for a program to modify its priority dynamically
- Support the notion of Background Observing Programs (BOPs).
These are low priority programs which sit in the background and are only
scheduled when neither a MOP or ROP are running.
The BOPs are there to soak up any idle time of the telescope
and ensure maximum utilisation of the telescope.
Typical example of BOPs are pointing programs.
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