undefined

points

[-]

  > Traditionally (pre-ai) you would use another image of the same part of the sky and negate the items that you want to remove from the image.

I'm not an astrophotographer, so I'm interested about why that method would work for stars. Are not stars fixed in relation to the images taken? I could see how the technique would work with planets, maybe, but not stars.

Why does the technique not work with aircraft? Because they generally fly on fixed routes?

by recursivegirth2 hours ago|

parent|

[-]

Earth moves - that's how you get the next shot without repositioning the telescope.

This time-lapse probably better visualizes it: https://www.youtube.com/watch?v=wFpeM3fxJoQ

by dotancohen2 hours ago|

parent|

[-]

As the Earth rotates over the course of the night, the background stars and nebulae move as a single unit, no?

Maybe for some close stars parallax might work to remove them over the course of half a year. But no way could the Earth's rotation during a single night move background stars out of a nebulae.

by hatthew2 hours ago|

parent|

prev|

[-]

Sure, but the nebulae also move along with the stars. The questions is how one can subtract the stars without also subtracting the nebulae. (I'm assuming different filters and/or a database of known star positions)

by dotancohen1 hours ago|

parent|

[-]

The ESA catalog is not precise enough to remove a star from an image of the structure of a nebulae - never mind Hipparcos. Filters while photographing and image processing in post are the way to go.

Don't forget that not only does the star need to be removed, but also the diffraction spikes. Those are internal reflections in the lens assembly - not mapped by any star catalog ))