How different do these appear in an 8 inch scope...(skyquest xt8).. I was out last night observing and found M51 which was very discernable...I know M101 is a spiral galaxy but  I'm not quite sure what I was looking at when trying to find M101.. Will M101 be dimmer than M51 even though M101 has a lower magnitude?... I read something about the light form M101 is more dispersed.. so the object that I thought was M101 was very, very faint and appeared as a large round sphere...... Is this what M101 should look like?? I guess what I am asking is "Has anyone seen M101 in an 8 inch scope? What does it look like? and Does it appear dimmer than M51?

The two are certainly different animals.
Despite its brighter magnitude m101's larger area translates into a lower overall surface brightness. M101's threshold detection begins with its smaller 'stellar' core and seemingly unattached spiral knots. M51/ngc5195's more compact and uniform surface brightness can allow most of its core and spiral glow to pop out all at once.
Side by side: http://tinyurl.com/5f3ph3

SJS

M101 has the lowest surface brightness of all the Messier galaxies (14.8 magnitudes per square arcminute) but is visible as a fuzzy, circular patch through a binocular or a small telescope from a dark site.  I've observed it many times with my 101mm Tele Vue refractor.  M33 and M74 also have low surface brightnesses and are similarly difficult to observe from a light polluted locale.  Under dark skies, a DSO with a surface brightness of 12.5 magnitudes per square arcminute or brighter should be visible in almost any instrument, one with a surface brightness of 13.5 can be called average, and one with a figure of 14.5 or fainter can be considered a challenge object. 

Both M51 and M101 looked fantastic through John Vogt's 32" f/4 ATM Dob last Thursday night at the 2008 Cherry Springs Star Party.

Dave Mitsky

saberscorpx thanks for the info... very helpful... the side by side pic was exactly what I needed to see... thanks again

Dave.. I also appreciate the info... very helpful

conclusion.... I think I did find M101

stargzr:

"Has anyone seen M101 in an 8 inch scope? What does it look like? and Does it appear dimmer than M51?

What you describe is exactly what you should expect from your telescope.  M51 is more condensed (you should be able to see the smaller companion galaxy NGC 5195 as well) and pops out against the background nicely, like a glowing ember.  M101 will appear like a round, faint, cloud of smoke is comparison.  With time, patience, and a trained eye you will be able to make out some of the spiral structure in M51 on a good night.  Congratulations .

 SJS - The rendition of the two objects are good except that I would think M101 would be much larger in apparent size that M51. True, its surface brightness is very low but its central nucleus should ( I believe) be depicted as larger, though fainter than M51's appearance in a telescope or binoculars.

    My statement/question derives from the fact that though I have tried to observe this elusive object many times, I have not yet had a reasonable good view of it (just a hint of the nucleus with averted vision). I'm wondering if my assumptions are correct?  Mr Q
 

 Stargzr

If you had your 8" pointed to where M101 should be and you could detect a faint blurry white spot, you probably had it in your EP.

There's only one observing aid for galaxies that works. That's dark sky and dark sky and darker sky.

On many nights I can see 101, 51, and others naked eye from my house, but few anymore have such sky and it's too bad. And I thinks it's unfair to reference the views of such objects through 20s and 30s and 40 inch apertures, few amateurs will ever have a chance to look through such scopes. I have a 12.5" and the chance of my ever having anything bigger is zip.

Once you've identified such dim galaxies and can return to them again and again, each time your observing skill improves and when you can use your scope from good dark skies you'll see details you hadn't noticed before.

The DSS thumbs are to scale. 101 is measured across the outer knots. Also, picture 51 without 5195 as company.

SJS

johnm:

On many nights I can see 101, 51, and others naked eye from my house, but few anymore have such sky and it's too bad. And I thinks it's unfair to reference the views of such objects through 20s and 30s and 40 inch apertures, few amateurs will ever have a chance to look through such scopes. I have a 12.5" and the chance of my ever having anything bigger is zip.

Hmm, both M51 (magnitude 8.4) and M101 (magnitude 7.9) are too dim to be visible with the unaided human eye.  Brian Skiff, a professional astronomer at the Lowell Observatory, has a list of naked-eye DSOs posted at ftp://ftp.lowell.edu/pub/bas/deepsky/nakedeye.dso and, while the Messier galaxies M31,M33,M81,and possibly M83 have been sighted, M51 and M101 have not.  M81 is extremely difficult to see naked-eye and probably represents the farthest object that the human eye can see without optical aid.

Any amateur astronomer who attends a star party is likely to catch views through scopes in the 20 inch, and possibly larger, aperture range.

Dave Mitsky

 Let me put it to you this way. I know what my eyes can see. And not everyone lives anywhere close to where star parties may be held.

What's your LVM?

You're about to get a new neighbor.

SJS

I recon LVM here generally around 7.7-7.8.

One of the reasons I live here is there aren't any neighbors. A light about 5 miles away drives me nuts and I can see a porch light on a house about 10 miles off as the crow flies if they turn it on. 

Sounds like a little piece of heaven, John.  I consider myself lucky, and my skies are only 5.5 to 6.  Last weekend I saw M13 naked eye for the first time and was thrilled with that.  And you are right, I'd have to travel a long way to attend a star party where I could get a few minutes at the eyepiece of a large aperture scope.  It's just not an option for many of the folks on these forums.

 The sad part about dark skies is that there probably isn't any pristine sky left on the planet except possibly in the southern hemisphere. If you get away from all man made light there's still dust and vapors in the sky that's man made or caused.

I'm sorry but I am going to have to side with Dave on this one.  Even under the best conditions the human eyes are incapable of seeing those objects. Especially an object such as M101 which may be a magnitude 7.9, however, has a very low surface brightness of only 14.8. Even small aperture telescopes have a difficult time of that one,   M51 is magnitude 8.4 with a surface brightness of 12.6  Both are well beyond the limitations of even the best eyes under the best conditions.

Have A Nice ________

The faintest thing seen by eye as magnitude 6.5?  By eye in the daytime at -3.9? The faintest binocular objects possible as 9.5!!??

I don't know who came up with those figures, but I know some who would take serious issue with them.

As far as seeing 101 with the naked eye, if I can look up where it is and see a white smudge and put the glasses or a scope on it and it's the galaxy, that's good enough for me. 

Neptune must be a piece of cake.

SJS

Tim:

Where did you get that list? The links don't work, so I assume you copied it from an online source where the links do work.

There are some notable flaws in the list, but they may depend on explanations made at the (non-working here, at any rate) linked pages.

For example, the binocular statement clearly depends on which binoculars. Our Giant Fujinons can go way beyond what's quoted here, down around 14 or so.

Naked-eye limits depend not only on individual visual acuity, but also on sky conditions. On a photometric night at CSAC, I can go to about 7 zenithal and have done so on many occasions. A photometric night is exceptional for most locations, of course. John M's conditions could be exceptional a better than average percentage of the time, given his location. I am currently mapping CSAC's skies nightly for a week each month, in an attempt to determine just how often we can go really deep there. With modern CCD imagers this is a relatively easy thing to do ... you just need the time(!).

When I was (much) younger my eyesight was extremely good, and I lived for many years in the desert Southwest and far-western Texas (the Trans-Pecos region). I never, however, saw M51 or M101 naked-eye. With my eyesight today, I probably couldn't do it even on a photometric night.

A good, quick test for me at CSAC is M27. I have seen it listed anywhere from V 7.4 to V 8.1, but it is clearly visible to me on many nights from CSAC, so it must be toward the brighter end of that range, perhaps more. It is also rather condensed, which helps visually. I also have seen, and pointed out to others at the time, NGC 253 naked-eye several times. Even though it is quite condensed, it's low altitude from Texas makes it a toughie, but at 32 to 34 N a photometric night with low extinction brings it in range.

Among my observing buddies, the ones I find routinely doing the seemingly impossible are mostly those who have spent a good deal of time as variable and double-star observers. Those activities really train the eye and the mind. In particular, observing doubles without prior knowledge of their position angles is an often humbling way to teach yourself about observational bias -- we often (don't really) see what we expect to see, and convince ourselves we truly have seen it. But following the rigor needed to tease out dim companions and later learn your measured PA was within measurement error of the actual measure can train you in going beyond the norm.

 The first time I noticed a glow, naked eye, at the position of M101 I was stunned. And have since observed it on a number of occasions, it's not a regular thing however even in these skies. And no chance for such observations for a while now since we're at just about no total darkness from this latitude.

One of my great enjoyments also was to walk outside at anytime Venus had some decent elongation and see it naked eye.

One night here I went to ~900X with my 12.5" on Saturn and saw near photographic detail. I consider seeing like that night a once in a lifetime thing, but I still have my notes and remember it vividly. 

There is a very big difference between visual limiting stellar (point source) magnitude, which certainly can reach into the seventh magnitude range, and the integrated magnitude of an extended DSO like a galaxy.  I have been observing for a long time and am familiar with most of the deep sky sites and astronomy fora on the Internet and have never before heard anyone claim that they could see M51 and M101 with the naked-eye.

I'm taking the liberty of posting Brian Skiff's naked-eye DSO list, as it appeared on the IAAC discussion board a number of years ago.  Take particular note of the first sentence.

Dave Mitsky

 Although many of the objects are easy or straightforward from a true-dark
site, in the marginal cases one must be very careful to sort out neigbouring
mag. 7 and 8 stars in order to make sure you've found the correct object.  It
makes one's claim more useful if such details are provided as well.  I can post
a discussion of what was necessary to identify M81, for example, if desired.
     I was pleased to see that Yann included Sharpless 264 (Sh2-264), the
very large nebula surrounding the lambda Orionis group.  I find this readily
visible from the Lowell Anderson Mesa site, but I don't think anyone's ever
mentioned it in print being a naked-eye object.  On the other hand I have
never convinced myself that I could see Barnard's Loop because there are so
many faint stars strung along it that can mimic nebulosity.  Still again, the
Rosette Nebula is pretty easy to see even from a somewhat light-polluted
site when using a UHC or [OIII] filter.  This is a good target to start your
challenging naked-eye viewing with, since the change in the size of the object
going from unfiltered to filtered is dramatic.

\Brian

==================================

Blanco 1  too sparse
Cr 065    not real
Cr 069    lambda Ori cluster, easy
Cr 070    Belt of Orion, easy
Cr 089    not real
Cr 106    not real
Cr 121    too sparse
Cr 132    too sparse
Cr 135    too sparse
Cr 140    too sparse
Cr 316    = Trumpler 24 (preferred name)
Cr 399    easy; Brocchi's cluster = Coathanger
Cr 464    not real
IC 0348   too faint
IC 1396   nebula readily visible
IC 1805   nebula too faint
IC 1848   nebula too faint
IC 4665   straightforward
IC 4725   = M25; easy
IC 4756   readily visible
IC 4996   too faint, too small
M002      probably visible
M003      straightforward
M004      easy
M005      straightforward
M006      easy
M007      easy
M008      easy
M011      easy
M012      probably visible
M013      easy
M015      straightforward
M016      straightforward
M017      straightforward
M018      too faint
M020      easy
M021      straightforward
M022      easy
M023      easy
M024      = IC 4715; easy
M025      = IC 4725 above
M028      background too bright?
M029      too small/faint
M031      easy
M033      straightforward
M034      easy
M035      easy
M036      straightforward
M037      straightforward
M038      straightforward
M039      straightforward
M041      easy
M042      easy
M044      easy
M045      Pleaides
M046      straightforward
M047      straightforward
M048      straightforward
M050      straightforward
M052      maybe too faint
M062      background too bright?
M067      straightforward
M081      tough but visible
M092      faint
M093      straightforward
Mel 020   = alpha Persei cluster
Mel 022   = Pleiades
Mel 111   = Coma Berenices cluster
NGC 0253  reportedly visible from the south
NGC 0281  too faint
NGC 0752  easy
NGC 0869  easy
NGC 0884  easy
NGC 1499  visible with filter
NGC 1746  straightforward
NGC 1981  straightforward
NGC 2232  brightest star only
NGC 2237  Rosette Nebula, visible with filter
NGC 2244  Rosette cluster, easy
NGC 2264  brightest star only
NGC 2451  easy
NGC 2546  easy
NGC 5128  reportedly visible from south
NGC 6124  straightforward
NGC 6231  easy
NGC 6530  = M 8
NGC 6633  easy
NGC 6871  too small/faint
NGC 7000  North America Nebula; straightforward
NGC 7243  background too bright?
NGC 7293  several reports (without filters!)
Sh2-264   lambda Ori nebula, straightforward (much easier than Barnard's Loop!)
Sh2-276   Barnard's Loop; often confused with encircling mag 5-7 stars
Steph 01  delta Lyr cluster; brightest star only
Stock 02  bright background, barely discernable
Tr 10     probably visible, but in very crowded