[Stonius (Markus)]

I'm ashamed to admit this is something I am having trouble conceptualising in my head.

I *think it's true to say that you can capture objects that are far fainter than the sky noise simply because the sky noise is random and the signal from the object is not. There is the randomness of shot-noise of course, but this is overcome by integrating many images (analogous to the fact that while raindrops fall randomly, two adjacent rain gauges will measure the same rainfall levels). In a nutshell; we remove the randomness with temporal averaging.

Please correct me if I'm wrong on the above - as I said, I'm still learning and trying to wrap my head around this.

Okay. So given that, how do we figure out the dimmest object that can be imaged with any particular setup? How buried in noise can a signal be before it is irretrievable?

I know it's a matter of how much time you have and diminishing returns. But if you wanted to figure out a practical dimmest object limit for your setup given ideal conditions (sort of like a photographic version of the naked eye limiting magnitude used in visual observing).

Apologies if this is a dumb question. :-)

Markus