Introduction and Safety

The acquisition and guide box (A&G) on the INT features a rotating flip mirror which directs the telescope beam to a high-gain Westinghouse TV camera, thus providing field or slit viewing at the Cassegrain Focus; there is no camera at Prime. The Westinghouse is a high (3000) gain video camera with a Grinnell digital integrating store. It is a very sensitive system and care must be taken in its use. There is an identical Westinghouse camera on the finder which can be directed to the Grinnell when wanted. This section is intended as a guide to the safe use of the TV Cameras, and how to get the most out of their facilities.

The very high-gain TV cameras can be quickly and
PERMANENTLY DAMAGED BY OVER-ILLUMINATION
by BRIGHT stars or BRIGHT lights.

Do not, therefore, operate the TV until you have read all of this Section and preferably have also been shown how to use it. If you suspect overillumination you should immediately press the FREEZE button and turn the gain down.

Some simple precautions to ensure a long life for the TV Camera:

1. Check that all dome lights, including torches, are turned off before turning on the camera.
2. Always view a field in DIRECT mode first, NEVER in AVERAGE or SUM.
3. Turn the gain up SLOWLY. The system time constant is about 3 seconds.
4. Never do a long integration with a bright star in the field.
5. Always turn the camera gain off BEFORE MOVING the telescope.
6. DO NOT TWIDDLE knobs at random.
7. If in doubt, press the FREEZE button and turn the gain down.