Rules of thumb

[Grogfish]

I have been working on an observing list of irregular galaxies. It’s short. And then I brought out my trusty rule of thumb for visibility of objects and the list became very short! (May well post about this topic elsewhere)

It made me wonder if it might be interesting to share our astro rules-of-thumb…

 

Ok, so my “visibility rule” is as follows:

Messier= I can see it

NGC= I can probably see it

IC= it should be called ICantC

PGC/UGC= 😂
 

Comments and contributions gratefully received, if only for comedy purposes!

[Paz]

I have a rough idea in mind of of what it is worth trying for from trial and error. Early on in my observing experience I planned out an epic galaxy hunting session in/around Ursa Major. I determinedly looked for one galaxy after another on my list, never giving up, and packed up at the end with a success rate of....... zero!

Light pollution being the issue, which I was aware of but I was far too optimistic about it's impact. So the rule arising from this was: If I'm getting excited about observing galaxies from home.... don't!

[Swoop1]

My Rule Of Thumb is this-

I feel like going out and Observing and Imaging. It WILL be overcast.

[DaveS]

If it's clear it will either be a full moon or blowing a hoolie. Or possibly both.

[Davesellars]

If i'm going to get the 12" dob out then for me I need reasonably good indication of transparency for observing DSOs.  You can normally get a feel for this in the afternoon while the sun is going down and if the sky looks a nice deep clear blue instead of whitish haze then I'll get the dob out early.  Later on if it's cleared and I can see down to mag 5 stars clearly then it's going to be OK.  Anything other than that i'll probably stick with a shorter session with the refractor.

BTW, there are many NGC objects that are way brighter than those in the Messier list.  I wouldn't see it another level of difficulty...

[LukeSkywatcher]

My rule of thumb:

If it looks like a cloud, it must be a cloud.