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Q for astronomy people: This is tracking the sky movement as it takes the pictures right? Also, with the atmosphere moving, is there a limit of how large the telescope can be and take photos from earth, before it can't get more quality?


At some point you'll be diffraction limited even at the scale of Earth. The larger your effective aperture, the better you can resolve. Adaptive optics helps get big telescopes closer to diffraction limited performance. That's the best you can do with a given optical system, barring some funky microscope setups. Trying to beat the diffraction limit has occupied a lot of very smart minds.

https://en.m.wikipedia.org/wiki/Diffraction-limited_system

Practically to go really big you need to use interferometry. There are radio experiments that can do this at Earth scale - the Event Horizon Telescope can image very small objects (black holes) by making simultaneous observations from all over the world. The telescopes point at the same place and use very very good timestamping. At the South Pole we have a hydrogen maser for that. Then all the data gets sent somewhere for correlation and a lot of processing. The analogy I like most is imagining you have a big mirror (Earth) but you've blacked out almost the entire surface except a few points where the telescopes are.

Radio is particularly amenable to this because you can build big dishes more easily than for visible light, and the diffraction limit is lower because it's proportional to wavelength/aperture. So in addition to big dishes, you're observation wavelength is much much longer (mm vs nm).

There's a log-log plot on that wiki page which is quite difficult to read, but the important point is that radio is all the way at the top and the best we have is the VLBA.

Visible interferometry is much harder...!


The atmosphere is always an issue, we can correct for many of the effects using adaptive optics, but there are always limits. The advantage you get from going bigger on the ground is that you are making a bigger "bucket" to put photons in. More photons = fainter objects are visible, this is the motivation for projects like:

https://en.wikipedia.org/wiki/Extremely_Large_Telescope

Typically for non-adaptive optics telescope the atmosphere will limit you to the scale of about an arcsecond. Meaning objects which take up less than an arcsecond of the sky will appear as points. Adaptive optics telescopes however have much better resolving power.


The seeing in Chile is closer to .7 arc seconds. Sub-arcsecond seeing for Rubin has already been achieved across the focal plane.


As I said, just an order of magnitude estimate for many non-adaptive optics telescopes.


it tracks the sky. The exposures here are never longer than 30 seconds for the normal survey mode. They bounced around a lot, it was going to be 2 15s images so you can do cosmic ray rejection (and other things)




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