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Astronomical seeing severely limits the efficacy of even multi-million dollar telescopes. The size of the pixels in this image is ~0.2 arcseconds, which is far

Astronomical seeing severely limits the efficacy of even multi-million dollar telescopes. The size of the pixels in this image is ~0.2 arcseconds, which is far below typical seeing limits even in excellent conditions.

bhouston 2y ago
Excellent seeing on earth is typically 0.4 arcseconds, so close. https://en.wikipedia.org/wiki/Astronomical_seeing https://en.wikipedia.org/wiki/Astronomical_seeing My setup gives me around 1.92 arc seconds for a point diameter.
- mnw21cam 2y ago
  And you can do tricks such as lucky imaging or active optics (depending on your budget) to further improve the resulting resolution. Lucky imaging is tricky on something as dim as Andromeda, but has been shown to be just about possible.
  - bhouston 2y ago
    I haven't seen lucky imaging used on dim objects by anyone I know. I personally do not have a large enough aperture to collect enough light for that. But I've used it on bright planets before via AutoStakkert[1]: https://www.astrobin.com/full/06dzki/0/ https://www.astrobin.com/full/06dzki/0/ [1] https://www.autostakkert.com https://www.autostakkert.com
    - mnw21cam 2y ago
      Lucky imaging was always a tool for use on planets and the moon. Anything bright. It's hard to do dim objects because there's less for the software to inspect in each frame to determine the luckiness and distortion, but you can maybe use fortuitous bright stars in the frame to index off. You also need to collect a huge number of images to get any sort of signal to noise ratio. This video is an example of the technique actually used on a dim object, though the results were fairly modest because of murky British skies. https://www.youtube.com/watch?v=5s9xbZ5G-wk https://www.youtube.com/watch?v=5s9xbZ5G-wk
- JBorrow 2y ago
  That 'excellent seeing' is for sites that are chosen for telescopes. Typical seeing from sea level is much worse: - https://www.ing.iac.es/astronomy/development/hap/dimm.html https://www.ing.iac.es/astronomy/development/hap/dimm.html - https://www.researchgate.net/figure/Fig-C1-Seeing-distribution-at-Paranal-from-2015-to-2020-as-measured-by-MASS-DIMM-and_fig4_381404231 https://www.researchgate.net/figure/Fig-C1-Seeing-distributi... - https://www.mdpi.com/2072-4292/15/9/2225 https://www.mdpi.com/2072-4292/15/9/2225 Around 1-2 arcseconds is 'good' seeing in your backyard. There is a good reason for telescopes to be on some of the tallest mountains on Earth.

bhouston 2y ago

Excellent seeing on earth is typically 0.4 arcseconds, so close. https://en.wikipedia.org/wiki/Astronomical_seeing https://en.wikipedia.org/wiki/Astronomical_seeing My setup gives me around 1.92 arc seconds for a point diameter.

mnw21cam 2y ago
And you can do tricks such as lucky imaging or active optics (depending on your budget) to further improve the resulting resolution. Lucky imaging is tricky on something as dim as Andromeda, but has been shown to be just about possible.
- bhouston 2y ago
  I haven't seen lucky imaging used on dim objects by anyone I know. I personally do not have a large enough aperture to collect enough light for that. But I've used it on bright planets before via AutoStakkert[1]: https://www.astrobin.com/full/06dzki/0/ https://www.astrobin.com/full/06dzki/0/ [1] https://www.autostakkert.com https://www.autostakkert.com
  - mnw21cam 2y ago
    Lucky imaging was always a tool for use on planets and the moon. Anything bright. It's hard to do dim objects because there's less for the software to inspect in each frame to determine the luckiness and distortion, but you can maybe use fortuitous bright stars in the frame to index off. You also need to collect a huge number of images to get any sort of signal to noise ratio. This video is an example of the technique actually used on a dim object, though the results were fairly modest because of murky British skies. https://www.youtube.com/watch?v=5s9xbZ5G-wk https://www.youtube.com/watch?v=5s9xbZ5G-wk
JBorrow 2y ago
That 'excellent seeing' is for sites that are chosen for telescopes. Typical seeing from sea level is much worse: - https://www.ing.iac.es/astronomy/development/hap/dimm.html https://www.ing.iac.es/astronomy/development/hap/dimm.html - https://www.researchgate.net/figure/Fig-C1-Seeing-distribution-at-Paranal-from-2015-to-2020-as-measured-by-MASS-DIMM-and_fig4_381404231 https://www.researchgate.net/figure/Fig-C1-Seeing-distributi... - https://www.mdpi.com/2072-4292/15/9/2225 https://www.mdpi.com/2072-4292/15/9/2225 Around 1-2 arcseconds is 'good' seeing in your backyard. There is a good reason for telescopes to be on some of the tallest mountains on Earth.