ok, for all the amateur-astronomers out there:

I am having the problem that I can not determine wether I can see a deep-sky object, when I know the magnitude.

Is there any way to find out about the relative brightness....must have something to do with the area of the object, the wider the object, the light of a certain magnitude is more spread out, and so on more difficult to see.

is there a way to know if you can see a deep-sky before getting into the dark?????

space ya!

Doesn't the magnitude tell you want you want to know? If it's not bright enough you won't see it. If it is, you will. Size is irrelevant.

Have a look at this page KneD it gives a formula for working out the limiting magnitude of a scope. It has a full run down on what factors will limit your viewing

http://www.cfarr.com/howtoseltel.html

Originally posted by James R
Doesn't the magnitude tell you want you want to know? If it's not bright enough you won't see it. If it is, you will. Size is irrelevant.

Size IS relevant, because as far as I know the magnitude is determined for the whole object, so while you can easliy see a 4th magnitude star, a 4 magnitude deep-sky wouldn't be visible....simply because the 'light' is spread out over an area much larger than the star-situation.

and also i have no problems with limiting magnitudes of my scope, know them already, when we're are talking about stars....with deep-sky objects it is very different...

how to find out about that?

How about this page KneD?

http://www.monmouth.com/~ksears/loso4.htm

woyeah, exactly what I meant, and everything I want to know, on that link.....

thx Boris!