8 The Instrument Rotator
8.1 Introduction
The telescope is equipped with an instrument rotator. The entire suite of instruments, including the MIS, are attached to the instrument rotator. The field orientation of the finder and guider cameras is therefore affected by the position angle of the instrument rotator.
8.2 MOVING THE ROTATOR
The instrument rotator can only be moved from inside the dome. The hand paddle controller (Figure 8.1) is stored on the south wall near the polar axle. The position angle of the rotator is displayed to the nearest 0.1 degree on the TELESCOPE MONITOR. A second monitor is provided in the dome; the cabinet is on casters and can be moved towards the telescope. A second FIND-GUIDE MONITOR in the dome can be used to align an object along a slit, etc.
DO NOT MOVE ROTATOR WITH THE MIRROR COVERS CLOSED !!!
To operate the instrument rotator:
The 2.4 meter should only be rotated with the observer directly viewing the underside of the telescope and paying attention to the cables. Pay close attention to the 2 power cables from the mirror cell (west and south east) to the rotator table. The main instrument cable loop may also become taunt, especially when working in the far north or south. The rotator can be moved by +/- 90 from its home position.
Do not switch between FORWARD and REVERSE when the motor is running. If you do, the unit will trip. Push the central square white button to reset the hand paddle.
When the rotator is at the mechanical zero point the central square white button will be illuminated (if the hand paddle power is on and the white button is pressed in).
The rotator position angle displayed on the TELESCOPE MONITOR can be changed through the xtcs TCS display pop-up window (section 5.4.8). You will normally only do this to reset the zero point of the rotator table.
The autoguider rotator angle must be reset for each position angle of the instrument rotator through the PC-Guider P command (section 7.3.3 and 7.5).
8.3 Instrument Rotator and Flange Mounting Dimensions
Guest instrumentation can normally be interfaced to the MIS modules (Section 6.8.1). When large back focal distances are required or the instrument has its own finder-guider system, it can be mounted directly to the instrument rotator table.
The rotator table has a detachable flange, also shown in Figure 8.2, which can be used to mount electronics boxes, etc.
The maximum total weight of an instrument mounted directly on the rotator table depends upon its distance and distribution from the instrument rotator, and is approximately 750 pounds (340 kg). A moving platform allows heavy instruments to be raised for attachment to the telescope. Please consult the staff at an early stage if you plan on bringing out your own instrumentation.
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