Re: Hydrogen clouds of the Bubble Nebula


Mike Dodd
 

On 9/9/2020 2:59 PM, Richard Hennig wrote:
Mike, I agree that satellite’s or planes are more likely to show up
in long sub-exposures. However, shouldn’t these trails go away when
you stack your image using the median of each pixel or
sigma-clipping? Those methods require that you have at least a few
sub-exposures to stack.
Possibly, but the real issue is, you need more than a few exposures to get a good signal-to-noise ratio. Signal increases directly with the number of exposures, while noise, being random, increases as the SQUARE ROOT of the number of exposures.

The more exposures, the better. and hour-long exposures limit how many you can acquire.

--- Mike

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