The Bahtinov Mask, a Focusing Technique for the MeerLICHT Telescope and the Commissioning at Sutherland, South Africa

Zandvliet, M (2017) The Bahtinov Mask, a Focusing Technique for the MeerLICHT Telescope and the Commissioning at Sutherland, South Africa. Master's Thesis / Essay, Astronomy.

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Abstract

We have investigated the implementation of a new focusing technique for the MeerLICHT telescope built by the Radboud University, the Netherlands. At the heart of this focusing technique lies the so-called Bahtinov mask which is placed in front of the aperture, a mask that contains a typical grid resulting in a diffraction pattern on the focal plane. A software tool has been written using Python to analyse the obtained images at the focal plane and calculate the best M2 focus setting for the optical system. Initial results using cross section Lorentzian fitting showed a lack of consistency and accuracy in acquiring the best focus. A combination of the Hough transform technique and Canny edge detection allowed for the determination of best focus values for stars having a SNR > 15. Obtaining the best focus value for stars with 10 < SNR < 15magnitudes requires very good seeing and no artifacts near the stars on the image plane. Stars having a SNR < 10 are not suitable for this software. A total of 79 stellar sources spread over 27 different images were selected to deduce the average best M2 setting to 151 ± 28 microns. This average was obtained from the 79 stellar sources that represent a total of 10 different stars in those 27 images. In order to improve the accuracy and the consistency of the software further, first steps were taken to model the resulting diffraction pattern for theMeerLICHT telescope in order to improve the fitting of the on-sky sources. Along with exploring the possibilities using the Bahtinov mask, the integration,installation and commissioning in Nijmegen the Netherlands and Sutherland in South Africa are part of this thesis.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Astronomy
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:33
Last Modified:	15 Feb 2018 08:33
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/16216

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