Just wondering if anyone has viewed the Whirlpool galaxy usning an 8" SCT or would a larger apeture be necessary?

M51 is visible through a 7x35mm binocular from a good dark site.  I've observed it many times using 80 and 101mm refractors, as well as far larger apertures. 

You should be able to see M51 and NGC 5194 and perhaps even a hint of M51's spiral arms through your 8" SCT, depending upon conditions and your observing skills.

http://www.clarkvision.com/visastro/m51-apert/index.html

Dave Mitsky

Thanks.  I thought it unusual that I saw nothing.  Long story short, it is a relatively new scope.  I used the GoTo and it pointed me into a part of the night sky that had nothing (visually speaking) in it.  I tested the GoTo on a couple of other objects and they came up dead center.  I just had to be sure that I"M not going crazy.  OK, maybe the night sky conditions weren't good for very deep DSO's?

M-51 looks beautiful in 20X80 binoculars from a dark site and M-51 and NGC 5194 are easily visible in a 6 inch scope even under lousy skies.  Just don't expect much detail.  For a large galaxy like M-51 dark skies make an incredible difference in what you can see.

Then I'll have to give it another try in another area.  Unfortunately, I live in an area of the state that suffers from the worst light pollution.  As "dark" as I thought the area around me was, obviously I'll have to find darker.

 Thanks

What magnification(s) did you use?  Many people buy into the myth that low power should be used on deep-sky objects. 

Dave Mitsky

First make sure you're finderscope is aligned with your telescope. Then when do your star alignment, if you haven't got a reticle EP use a short focal length EP for more acuracy. Then when you choose the object for your mount to move to, start with a longer focal length eyepiece. Your using a long focal length SCT so you will want to start with no less than a 25mm EP. 
Allow your eye to adjust to the view through the EP using averted vision.  You should be able to see the faint butvery recognizeable shape of the Whirlpool and its companion. Then step it up from there. It should look pretty good with a 8" SCT as long as your skies are dark.

I started off with a 32mm 2" eyepiece.  I could go to 25mm, but as I said, there was nothing there.  My finderscope is aligned almost perfectly and all objects show up dead center in the finderscope and the tube. It was just bizarre because all other objects that I punched in came in just fine.

Also rememeber that 51 is huge, much larger than many other galaxies so the light is spread out and the contrast is poor.  Move the scope around and use averted vision.  You might just see a slight glow in the darker background until you get used to it.  M-101 is also like this and in polluted skies 101 can be a difficult galaxy to find even though it is quite bright.

 Also I agree with Dave that higher powers help greatly on many galaxies, increasing the contrast with the background.  Just rememeber that with higher power you probably won't see the entire galaxy in your field on view.  However, there really is no subsituted for dark skies when looking for detail in large galaxies.

Thanks, all for your insight.  I'm going out tonight into a much darker area and we'll see what happens.  I'll keep the size of the object and the FOV closely in mind.

Just another thought on large galaxies.  When I lived in New Mexico I could frequently see M-33 with the naked eye.  But even under those conditions I always though it looked far more pleasing with a 8X50 finder or large binoculars than with my 13 inch scope.  it was just too dang big.

M51 is 11 x 7 arc minutes in apparent size, which I would not characterize as huge, although it is larger than most.  (For the sake of comparison, M33 subtends 73 x 45 arc minutes.)   

M51 is fairly bright, having an integrated magnitude of 8.4 and a rather healthy surface brightness of 12.6 magnitudes per square arc minute.  The face-on galaxies M33, M74, and M101 are far more difficult to see from less than dark sites, since they have low surface brightnesses of 14.2, 14.4, and 14.8 magnitudes per square arc minute respectively.

Dave Mitsky

From a driveway or backyard, assuming some light polution, it is a difficult target.   You should see two fuzzy "stars" (the brighter centers of the of the two objects), M51 and it's smaller companion.  From a dark sky, away from city lights, you should see some evidence of the spiral structure....a glow around one of the fuzzy "stars".

Hi everyone,

I viewed M51 a few weeks ago for the first time.  I have light-polluted skies - limiting magnitude at zenith at the time I viewed the galaxies was about 4.5.  Using the Zhumell Z12 12" scope and a 9.7mm plossl EP, I could only see the bright cores of both galaxies, but no structure.  I made the following sketch:

Last year I recall searching many times for M51 and not finding it.  I was using a 5" reflector at the time.

Note that I am fortunate to have a very dark observing spot despite the sky glow (very little light intrusion from neighbors).  This allows my eyes to get as dark adapted as possible. 

 A few weeks ago, i saw m51 through my 5 inch relfector using the 32mm possl eyepiece under the extremely light polluted skies of SLC. the galaxy was very very, and i mean VERY faint, and i had to "shake" the telescope a bit to even detect it.

Orionis2009:

 A few weeks ago, i saw m52 through my 5 inch relfector using the 32mm possl eyepiece under the extremely light polluted skies of SLC. the galaxy was very very, and i mean VERY faint, and i had to "shake" the telescope a bit to even detect it.

You mean M51? 
M52 is an open cluster in Cassiopeia

 yeah m51 (whirlpool galaxy)....sorry for the typo

 I am new to all of this but I tried to find it on my scope few days ago and no luck. I guess I have to learn star hopping little more to find it. For example, I spotted Ring nebula fairly quickly, but this one got away from me... for now.  I used 38mm (2") and 25 EPs.

Edit: I think I just realized that I was actually looking to find M101, not M51. Both are in Ursa Major. 

Vlad1980:

 I am new to all of this but I tried to find it on my scope few days ago and no luck. I guess I have to learn star hopping little more to find it. For example, I spotted Ring nebula fairly quickly, but this one got away from me... for now.  I used 38mm (2") and 25 EPs.

 

Edit: I think I just realized that I was actually looking to find M101, not M51. Both are in Ursa Major. 

Actually M51 is in the Canes Venatici Constellation

There is a asterism of 3 stars forming a triangle near the vicinity of M51, if you can find that you will have no problem finding M51 provided you have clear dark skies. Although it can be found using low magnifications under dark skies, that is one galaxy that benefits from higher magnification and averted vision.

 Thanks!

Next clear night I will try to look for it as well as M51.