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Old 11-07-2017, 01:00 PM
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Atmos (Colin)
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Join Date: Aug 2011
Location: Melbourne
Posts: 6,385
Most of this is good on paper but isn't overly practical in the real world when it comes to a "virtual telescope".

With radio telescopes it is very useful as it allows for a resolution increase where the resolving power of the radio telescope is determined from the distance betweeen detectors. As the wavelengths get longer the larger the telescope that is required to achieve the same resolution.

For optical telescopes, due to atmospheric dispersion anything over 10" is virtually redundant from the standpoint of resolution (always limited to seeing conditions). Radio wavelengths don't have the same issue with atmospheric seeing conditions so larger absolute aperture (using many detectors over a wide area) is a good idea.

With Dragonfly, the resolution is limited by the image scale used, not by optics or seeing. If all 48 are used at F/2.8 it could be said that it is running the same as a virtual single 400mm F/0.404 lens. This is about as accurate as me saying that if I captured 5 hours of data with my Sigma 85mm @ F/2.8 with 120s subs that it has been captured as a single 120s shot with a 85mm F/0.2286 lens.
Or maybe 10x 120s exposures with a 85mm F/0.723 lens.

Unless you're wanting to increase image resolution with radio astronomy, telescope arrays are used because it is either more financially viable to have many smaller telescopes than one bigger one or you want to have a specific FOV and capture a lot of data in a short time (Dragonfly).
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