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JWST is observing the infrared only and has a narrow field of view. Euclid is wide-angle with both visible and infrared capabilities.

superposeur 3y ago
Thanks — is there a short answer to what can wide angle get you?
- mr_mitm 3y ago
  Euclid aims at measuring the shape of as many galaxies as possible to observe statistical effects that let us draw conclusions about the dark matter distribution
- anigbrowl 3y ago
  Literally what it says - a wider field of vision. Read the text on the ESA page.
- 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 ago
    Not 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.
- pixl97 3y ago
  Star/galaxy surveys. For example there were a bunch of articles recently about 'stars disappearing'. That's because we take snapshots of wide ranges of the cosmos every once in a while and compare them. We can use this to figure out the direction and velocity of stars in our own galaxy. And in some cases things appear and disappear that are rather unexpected. You don't get that from narrow angle photos.
- ajross 3y ago
  More data. Euclid is for filling databases with survey data covering large-scale structure in the universe. Webb is for looking at very small, very distant single objects. Two different instruments for two different experiments. Consider comparing a fancy DSLR with a telephoto lens to a night vision security camera. Each does what the other can't, and you deploy them for different tasks.
- Sharlin 3y ago
  Should also note that "wide angle" is very much relative and in this case means "about the apparent size of a full Moon in the sky" – so vastly different from what a photographer would mean by "wide angle" =)
  - dylan604 3y ago
    it is a telescope after all, so of course it's going to be scoped in. anyone confusing wide angle photography with a telescope is just not comprehending concepts very well.
    - Sharlin 3y ago
      Eh, yes, because this is not an astronomy forum, there may be plenty of people who don't have a good idea of what "wide angle" means in that context. So IMNSHO a clarification was entirely appropriate, and thinking otherwise is rather arrogant. I didn't mean that "wide angle" would mean something like a 24mm camera lens, but more that it's much more narrow than even long telephoto focal lengths like 200mm or 400mm or even 600mm! Especially given that this is a survey mission whose purpose is to image large parts of the sky, it could be entirely plausible to a layman that its angle of view were much wider than 0.7 degrees!
PlutoIsAPlanet 3y ago
How's the Nancy Grace Roman Space Telescope compare to Euclid?

superposeur 3y ago

Thanks — is there a short answer to what can wide angle get you?

mr_mitm 3y ago
Euclid aims at measuring the shape of as many galaxies as possible to observe statistical effects that let us draw conclusions about the dark matter distribution
anigbrowl 3y ago
Literally what it says - a wider field of vision. Read the text on the ESA page.
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 ago
  Not 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.
pixl97 3y ago
Star/galaxy surveys. For example there were a bunch of articles recently about 'stars disappearing'. That's because we take snapshots of wide ranges of the cosmos every once in a while and compare them. We can use this to figure out the direction and velocity of stars in our own galaxy. And in some cases things appear and disappear that are rather unexpected. You don't get that from narrow angle photos.
ajross 3y ago
More data. Euclid is for filling databases with survey data covering large-scale structure in the universe. Webb is for looking at very small, very distant single objects. Two different instruments for two different experiments. Consider comparing a fancy DSLR with a telephoto lens to a night vision security camera. Each does what the other can't, and you deploy them for different tasks.
Sharlin 3y ago
Should also note that "wide angle" is very much relative and in this case means "about the apparent size of a full Moon in the sky" – so vastly different from what a photographer would mean by "wide angle" =)
- dylan604 3y ago
  it is a telescope after all, so of course it's going to be scoped in. anyone confusing wide angle photography with a telescope is just not comprehending concepts very well.
  - Sharlin 3y ago
    Eh, yes, because this is not an astronomy forum, there may be plenty of people who don't have a good idea of what "wide angle" means in that context. So IMNSHO a clarification was entirely appropriate, and thinking otherwise is rather arrogant. I didn't mean that "wide angle" would mean something like a 24mm camera lens, but more that it's much more narrow than even long telephoto focal lengths like 200mm or 400mm or even 600mm! Especially given that this is a survey mission whose purpose is to image large parts of the sky, it could be entirely plausible to a layman that its angle of view were much wider than 0.7 degrees!

PlutoIsAPlanet 3y ago

How's the Nancy Grace Roman Space Telescope compare to Euclid?