Hamburg 2016 – scientific programme
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T: Fachverband Teilchenphysik
T 80: Gammaastronomie IV
T 80.4: Talk
Wednesday, March 2, 2016, 17:35–17:50, VMP9 SR 27
FACT -- Normalized and Asynchronous Mirror Alignment for Cherenkov Telescopes — •Sebastian Achim Mueller1 and Jens Buss2 — 1ETH Zurich, Switzerland — 2TU Dortmund
Imaging Atmospheric Cherenkov Telescopes (IACTs) need fast and large imaging optics to map the faint Cherenkov light emitted in cosmic ray air showers onto their image sensors. Segmented reflectors are inexpensive, lightweight and offer good image quality. However, alignment of the mirror facets remains a challenge. A good alignment is crucial in IACT observations to separate gamma rays from hadronic cosmic rays. We present a star tracking alignment method which is not restricted to clear nights. It normalizes the mirror facet reflections to be independent of the reference star or the cloud coverage. It records asynchronously of the telescope drive which makes the method easy to integrate in existing telescopes. It can be combined with remote facet actuation, but it does not need one to work. Furthermore, it can reconstruct all individual mirror facet point spread functions. We present the method and alignment results on the First Geiger-mode Photo Diode Avalanche Cherenkov Telescope (FACT) on the Canary Island of La Palma, Spain.