A Fourier method for the determination of focus for telescopes with stars
Abstract
We introduce a Fourier method (Fm) for the determination of best focus for telescopes with stars. Our method fits a power function, that we will derive in this paper, to a set of images taken as a function of focuser position. The best focus position is where the power is maximum. Fm was first tested with small refractor and Schmidt-Cassegrain telescopes. After the successful small telescope tests, we then tested Fm with a 2 m Ritchey-Chrétien-Coudé. Our tests show that Fm is immune to the problems inherent in the popular half-flux diameter method.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2022
- DOI:
- 10.1093/mnras/stac189
- arXiv:
- arXiv:2201.12466
- Bibcode:
- 2022MNRAS.511.2008T
- Keywords:
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- methods: analytical;
- methods: data analysis;
- methods: numerical;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Published by Oxford University Press on behalf of the Royal Astronomical Society