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- Mounting holes : The main mounting point on the WHT Cassegrain
A&G unit is the outer
flange, with 16 16.5 mm diameter holes on a 1200 mm PCD. The same set of
mounting holes are repeated on the instrument rotator flange. In addition, to
mount smaller instruments, there are 2 sets of 12 M10 tapped holes on PCDs
of 457 and 635 mm.
- Maximum mass and moments: For instruments mounted on the A&G unit,
allowed mass is 1000 kg and the maximum moment is 1600 kg m.
For instruments mounted
directly on the rotator flange, the maximum mass is 1500 kg and maximum
1800 kg m. Note that even small lightweight instruments can cause problems,
since the telescope must be rebalanced to compensate and there is, at present,
no simple method of doing this.
- Clearances: The allowed size for instruments mounted on the Cassegrain
A&G unit is 3500 mm diameter and 2000 mm length.
Tue Aug 15 16:42:46 BST 1995