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The AAT building

The AAT building is a six-storey circular concrete structure, and observers normally enter through the main north doors. A lift and stairs near this entrance both give access to all floors. There are two other entrances to the building: one, to the south-east, is for tourists and provides access to the visitors' gallery while the other, to the south-west, is used as a fire escape. Stairs and lifts are adjacent to both these entrances, but only go as far as the main floor (level 4).

Figure 2.20 shows a cross-section of the building. There are floor directories near the entrance doors, and on each floor. The reception office on level 1 (office floor) is staffed during the daytime on weekdays, and can provide much helpful information. Level 1 also has several offices for visiting observers as well as the library, chart and catalogue room and a measuring room.

The other main areas of interest to visiting observers are the computer terminal room on level 2, the lecture/conference room on level 2.5 (between levels 2 and 3), the instrument preparation room and coudé foci on level 4 and the telescope console room on level 6.

 
Figure 2.20: The AAT building

The dome

The dome is a steel structure, vented and insulated to reduce heating of the inside air during the day. An up-and-over shutter gives access to the sky and protection from wind gusts is provided by a rigid windscreen which allows the telescope to observe through a (6.5m x 5.3m) opening. This opening is automatically aligned with the telescope tube when observing under computer control.

The space between the outer steel skin of the dome and the inner insulated skin can be ventilated by fans. The same fans and their associated louvres can be switched to exhaust the dome air and replace it with air entering either through the open viewing aperture or injected by large ventilation fans on the second floor. These fans will be switched on by the night assistant when needed.

The telescope and instruments are controlled from the console room on level 6. No food or drink may be brought into this room, but the small observers' lounge on the same floor has a refrigerator and microwave oven as well as facilities for making tea and coffee. Toilets are located on the console floor (level 6), the office floor (level 1) and the main floor (level 4).

Observers should be aware that the dome floor and console level walkways can be dangerous places at night when the telescope is in darkness. No-one should enter these areas after dark unless they are already familiar with this part of the building.

For new observers, the support astronomer can arrange a tour during the afternoon or before the lights go out. Torches (or flashlights) are available next to every entrance to the dark areas of the dome. Astronomers entering these areas must take one of these traches with them, and return it when they leave the dark areas. Astronomers entering these areas must also let the night assistant know that they are going out into the dome.

Access to the telescope foci

The prime focus access platform is reached from the console floor via stairs from the lift lobby. The telescope must be slewed to 77° zenith distance north to allow access to the prime focus cage.

The Cassegrain cage is reached via an access ramp from the north of the console floor. Parts of this ramp rotate with the polar axis structure as the telescope moves in hour angle, so it is only possible to enter the cage when the telescope points near the zenith. The Cassegrain cage door has an interlock which prevents the telescope moving while the door is open.

The coudé foci are easily accessed from the coudé slit area at main floor level (level 4), and the two coudé instrument rooms can be reached from the main floor, either from the telescope side or via `air-lock' doors from the building side.

Power, lighting and services

Australian mains voltage is 240V, 50Hz. If the mains power fails, a standby generator will take over the supply on the mountain within 30 seconds.

The AAT also has an uninterruptable power supply to which the computers and instruments are connected. There are sockets for raw mains and the no-break supply in the Cassegrain and prime focus cages and various other parts of the building.

All areas of the building except the darkrooms are fitted with fluorescent lights, and about 10% of these are connected to the no-break supply. Rooms where observers may wish to retain their dark adaption have both fluorescent and tungsten lamps. Special low-level lights are fitted in the coudé east room, following the discovery of fluorescent after-glow which can interfere with UCLES observations of faint objects. Lights near the telescope and observing areas can be kept switched off by a master switch in the control room.

Observers who bring their own instruments will find a well-equipped electronics workshop for emergency repairs and alignment. The machine shop facilities are shared with the ANU and are not normally available to visitors, but the shop staff will attempt small jobs wherever possible. Vacuum equipment includes a small pumping station, diffusion pump and leak detector. Pure N2 is available around the building at about 400 kPa. There are numerous outlets, each with its own adjustable regulator. Dry air is available at about 100 kPa in the Cassegrain cage, the coudé and vacuum lab areas.



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Next: The Schmidt Telescope Up: The Anglo-Australian Telescope Previous: Seeing measurements



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