Care and Feeding of a CAT

  • Rod Mollise
Part of the Patrick Moore's Practical Astronomy Series book series (PATRICKMOORE)


You wouldn’t expect a car to go tens of thousands of miles without a tune up, and you can’t expect an SCT to put in night after night under the stars without some maintenance, either. The most frequent and important task for SCT users is collimation, the procedure for adjusting the alignment of the telescope’s mirrors. Renowned Sky & Telescope columnist Scotty Houston once said, “Collimation is the number one killer of telescopes.” If an SCT is to perform up to snuff, its mirrors must be precisely aligned. The 5x magnifying secondary mirror in these scopes means small errors are exaggerated. Even a slight misalignment of the secondary mirror will wreck images. Unfortunately, many SCT users are afraid to collimate their telescopes, don’t collimate correctly, or don’t collimate frequently. That’s a shame, because collimation is a trivially simple operation to perform on SCTs. You just have to resolve to do it.

SCT Collimation

There’s only one way to successfully collimate an...


Diffraction Ring Primary Mirror Backing Plate Secondary Mirror Secondary Assembly 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Rod Mollise
    • 1
  1. 1. AL

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