Ad Astra Observatory

While I was testing out the Ha filter last night, I decided to test out a theory.

Like most astrophotographers, I take lots of short subframes of my subject, then stack them together into a longer “integration time” image.

I hardly ever get to do side-by-side comparisons of these image stacks against single subframes of longer length.

But, I’d done a run of fifteen 5-minute images, and was finishing up, so I decided to run a single 20-minute image to compare them.

Here’s what I got:

Note that you can see lots of hot pixels in the single frame. But, barring those, the longer subframe captured at least 1 magnitude more stars, but the nebulosity is noisier and less detailed. The stacked image has fewer stars (due to the shorter subframes), but the nebulosity looks smoother.

Not a definitive test, but certainly food for thought.

Also, 20min subframes of this object are definitely desirable.