Australia Telescope National Facility

ATUC Meeting
Triennium Funding - Science Case

at the ATNF in Epping, Sydney

- March 23, 1999 -

Telescope Operators for the AT Compact Array

The operator is the person responsible for the control and monitoring of the telescope. The ATCA is usually controlled via the computer program (user interface) CAOBS. The observation and Array systems are also monitored by computer - VIS, CAMON etc. Most important for monitoring is the program ASSISTANCE - a "well trained" program which can recognise a variety of system conditions which may threaten the data or the Array and in some cases offer the operator some limited advice on corrective actions. We can enumerate several types of telescope operator.

1. The Astronomer
At present (and since operations began in 1990) most observations are conducted by one of the astronomers associated with each project. The astronomer may be present at the Observatory, or operate the Array remotely via the computer network (usually from ATNF, Marsfield, but occasionally from other locations such as Hobart, Melbourne or Canberra). In the case of remote operation, the Duty Astronomer (DA) at the ATCA is responsible for assisting the astronomer in any operations not possible remotely, such as the manual setting or resetting of equipment.

2. Observatory staff
This option is discussed below.

3. None - automatic operation.
We might envisage routinely operating the Array unattended. In fact observations for individual projects run with little or no operator action required after the initial setup and START command. We should ask why we cannot, for example, run automatically from 4pm until 8am each day. In practice observations are often interrupted by events which require manual corrective actions but usually contribute very little to down-time.

i) Power interruptions - (antenna drives are not on UPS) These are frequent - perhaps once/day during summer. A simple restart is usually sufficient for recovery.
ii) Computer communications. Brief interruptions often arise from some loss of synchrony in inter-computer communications. Sometimes recovery is simple. At other times the symptoms can be confusing and considerable experience may be needed to recover. Completely eliminating this may be difficult while we continue to use a non-real-time operating system such as VMS in the control system.
iii) Weather. At present the antennas are stowed automatically on detection of high wind. However a manual restart is required. It would be possible to implement an automatic resumption of operation on declining wind speed. The reliance of automatic detection of impending thunderstorms needs further discussion.
iv) Other transient system faults. There is often some interruption from an undiagnosed system fault which may occur repeatedly for some time (days or more) until a solution is found. During that time recovery may be simple but requiring manual actions.

Clearly some of these interruptions could be handled automatically with modest changes to the current system. Perhaps such changes should be considered independent of the discussion on staff operators.

Staff operators.

1. How many?
Assuming operators work for 48 weeks each of 37 and we require operation all year (8766 hours) 5 (4.84) positions would be required.

2. Duties.