The basic operation modes

The actual control of ALMA observations will be run by the ALMA operations staff. There will be basically four modes of operation, with increasing levels of automation:

1.

Through a technical interface, allow/deny technicians complete access to all the control points available on each device, for debugging and maintenance purposes. The system should include such a facility, under control of the operator, for determining whether the device is to be used for observing or is withdrawn for maintenance.

2.

Control the array in manual mode. This mode will allow direct control on the hard-real-time system and on the quasi-real-time system (see below). This will provide a way to test all the functionalities of the array, as well as to develop and debug new ways of observing.

3.

Start astronomical observations or array calibrations in the interactive mode. This will pass the actual control of observations to the interactive astronomer (guest or staff), through a graphical interface. This interface will allow control of the observing process, with automatic feedback from the data pipeline. The astronomer and/or the operator will have the possibilities to interrupt a sequence of events at any time, to modify the observing strategy, to switch to a different mode to perform needed but unforeseen calibrations, or to switch to the dynamically scheduled observing mode.

4.

Pass control to the dynamic scheduler, which will select among its queue the observing project the most suitable for the current observing conditions, and run it in the most efficient way, using up-to-date environment parameters from both the real time system and the data pipeline. Though scheduled in a different way, the available observing modes will be the same as for interactive scheduling; in fact the astronomical parameters will have been input by the astronomer (PI/CoI), with the same graphical interface as above, but used long before the actual observing. Projects requesting to be scheduled at a precise time, like VLBI, or observation of comets, occultations, .. etc. will be included here but with a top priority in a narrow time window.

For ALMA we need the possibility of dividing the antennas in several sub-arrays: for instance, assigning some antennas to an interactive observer or to the dynamic scheduler, and others to operations staff for pointing model determination, baseline determination, or engineering tests. Sub-arrays will be operated simultaneously, each sub-array being in any of the four above modes. Selecting any antenna for a sub-array in a given mode will automatically make it unavailable from the higher-level modes, if used by any; the higher mode observing process will be notified and perform any needed calibration observations before releasing it to the requesting lower-level mode.

In the next two subsections (2.2, 2.3 we describe the basic requirements on the manual mode of operation, and on the interactive mode. The requirements on the dynamic scheduler are detailed in a specific section (4).