next up previous contents
Next: Nasmyth acquisition and Up: Acquisition and guiding Previous: Overview

Cassegrain acquisition & guider Unit

 

The layout of the Cassegrain A&G Unit is shown in Figure gif. It is described in some detail in La Palma Technical Note 56. Briefly, the unit has a full field of 15 arcminute diameter at the nominal telecope focus, 15 cm below the A&G to instrument interface. The following functions are provided

  
TIFF ]

TIFF ]

TIFF ]

Figure: Three views of the Cassegrain acquisition and guider unit for the WHT. (a) Plan, showing the autoguider, cable wrap and filter slides. (b) Elevation, showing TV, autoguider and comparison system. (c) Elevation, showing the large and small feed mirrors and the auxiliary port.

The recommended method for finding guide stars is to select them from the Space Telescope Guide Star Catalogue (GSC) using the GSS software described in section gif. The coordinate conversions between position and probe coordinates are given in ``The Guide Star Search Software: Preliminary User Guide, by R.A. Laing.



next up previous contents
Next: Nasmyth acquisition and Up: Acquisition and guiding Previous: Overview




Tue Aug 15 16:42:46 BST 1995