The JKT Acquisition and Guiding box (JAG)

The Acquisition and Guiding Box for the JKT was first tested on the telescope in 1987 August. It is specifically designed to operate with the CCD camera and will accept all standard RGO cryostats. Figure 4 shows the essential features of the instrument.
The main features are as follows:

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The filter wheel with 6 slots for 50x50mm filters. It has a raised index with a V-shaped indent located between positions 6 and 1, which is used to initialize the wheel.
Check the ING filter database to see which filters we have currently available:
http://ing.iac.es/ quality/filter/newfiltdoc.html .

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A fixed rectangular flat with a circular hole set at 45 degrees to the optical axis which directs light to a standard RGO autoguider. The field of view is annular with an outer radius of about 17 arcmin and an elliptical inner radius of 10-13 arcmin. The PA of the major axis is usually east-west. Stars as faint as V=13 can be used for guiding but brighter stars are preferred. The autoguider moves on x-y slides and can examine the offset field from the flat mirror. It has an acquisition field of 2x2 arcmin.

The autoguider has two sets of filters: ND and colour. For the highest accuracy at large zenith distances, the colour filter should be similar to that of the CCD camera. This minimizes the effects of atmospheric differential refraction.

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An Westinghouse TV which gives a field of view of about 9.5x7.5 arcmin divided into 512x512 pixels, via an f/15 to f/7 converter lens and a moving small flat mirror which is placed in the on-axis beam to allow the TV camera to view the sky directly for field verification. Objects with V=15 can be seen in direct mode and V=20 at full integration in a dark sky.

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A six-blade iris CCD shutter.

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As of 1998 the JAG grisms and drift scan table have been decommissioned.

 

Figure 4: Schematic view of the JAG. The grisms and the drift table have been decommissioned; the CCD shutter is in between the main filter wheel and the CCD mounting plate