I don't see how this can be true especially if you have a fancy telescope tracking something, take 3-5 whatever many shots in succession and stack. It's astrophotography 101.

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thayne 13 hours ago | parent [-]

For professional astronomers, it really sucks if you only have, say, an hour of observing time on a big telescope, and then a few of your precious frames are ruined because of a satellite. And you don't always even know that the frame is ruined until later, or have the flexibility to take more frames if needed (because you submit the full observation plan ahead of time, and just get the results later), in which case one bad frame can mean you don't have enough good frames to get valuable data.

Or more generally, let's say 10% of frames have satellite noise. That means there is 10% less observing you can do in a night. For amateurs, that is annoying. For professionals, that means less science can be done.

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jefftk 3 hours ago | parent | next [-]

Where is 10% coming from? If you're focused on something far away shouldn't the fraction be <<1%?

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esikich 12 hours ago | parent | prev [-]

That's what I don't understand, how are they ruined? If you're so deep that you need minutes or hours of exposures, that satellite will blip past the frame so fast it's not going to matter. And if the exposure time is less than that, you stack.

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thayne 11 hours ago | parent [-]

1. The satellite is usually significantly brighter than the thing you are observing. Often bright enough to saturate pixels (which can spill over to adjacent pixels).

2. If you are doing photometry (measuring the brightness of something), even if the relative brightness isn't very much, it can introduce a lot of noise to the data. For many things, even the dimmest satellite is going to add more light than the change in brightness you are looking for.

Now to be fair for scientific research typically you can use the frame if the streak isn't too close to your object(s) of interest. And for pretty pictures you can often edit out the streaks. But even so, it's a problem more than you would think.

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esikich 11 hours ago | parent [-]

Is this what you do? Because I'm at least an intermediate with astrophotography with a camera, and even airplanes are a total non issue. If you're so deep into the sky that you actually need many minutes or hours on the same spot, the teeny tiny time that satellite is there is a non issue and easy to remove with math.

	▲	thayne 10 hours ago \| parent [-]
		Not any more. But in college I worked in an astronomy research group.