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A wide angle lets you image something like the Andromeda galaxy or nebula all at once in the same frame. A narrow angle is more "zoomed in" so to image a large
by giantrobot 3y ago
A wide angle lets you image something like the Andromeda galaxy or nebula all at once in the same frame.
A narrow angle is more "zoomed in" so to image a larger structure you'll need a lot of exposures and build a mosaic. It takes a lot longer which means you have to monopolize the instrument for a long time.
If you want to image large structures like galaxy clusters a wide angle telescope is more efficient. Since the lifetimes of telescopes are limited (fuel, coolant, etc) you want to spend that time getting the most data out of the instruments.
- mr_mitm 3y agoNot that you're wrong, but galaxies in our neighborhood aren't really of concern to Euclid. The mission is to determine the expansion history of the universe, for which we will observe billions of galaxies. The handful of galaxies in our local group, which don't contain any information about the expansion history anyway, are less than a drop in the bucket. Also, frames can just be stitched together if necessary. And Andromeda is larger than the field of vision of Euclid. A large field of vision just helps you cover a large amount of sky in a reasonable time frame.