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Two years ago during the New Moon weekends of September & October in the arid High Desert of Southern California , I was able to see plainly (without averted vision techniques) , 5 spiral arms in M33 & the entire helical structure in NGC7293 with my SN8 & a 12.4mm Meade 4000 series Plossl yielding 65x magnification . I have yet to find any publication stating that this kind of detail is detectable in either of these objects through an 8 inch scope .
Was I just lucky ? At the right place at the right time ? Or is the SN8 just an awesome telescope ?
At the time , I know that my 49 year old eyes are not the greatest , but yet I have seen this detail & it was truly amazing .
I am interested to hear what it takes or has taken for other observers to achieve this detail in these objects as I have been told that I am doing exceptionally well with my SN8 in seeing this detail so easily .
Book after book & magazine after magazine article lead one to believe that it takes 10 to 12 to 16 inches of aperture to see these details .
What do you think ?

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I don't see 5 distinct spiral arms in M33, but I do see considerable detail, even in an 8 inch aperture. I can see the two main arms as somewhat irregular arcs of detail (I have seen hints of the southern arm in my 100mm f/6 refractor at only 17x). The northern arm is a bit more broken, and fades out just before I hit the galaxy's large emission nebula NGC 604 (which is quite easy to see). I see a number of other patches and partial arcs at between 70x and 120x. There is a large diffuse segment southwest of the nuclear region between the two main arms that is sort of "Z" shaped, plus numerous very faint patches and spots across the face of the object. The outer halo is also slightly mottled at times, and appears stunningly patchy in 10 to 12 inch apertures on a good night (looks like a 4th of July "pinwheel", which gives the galaxy its often used name, "the Pinwheel Galaxy"). I like to use 98x on M33 in my 9.25 inch SCT, as it ups the scale enough for me to study the distinct patches.

On NGC 7293, the helical nature is tough to see without using an OIII filter, although I do get hints of it in the DGM Optics NPB filter. However, overall, the nebula still looks mainly like a big fuzzy donut. The OIII filter begins to show some of the arc-like detail on the western side, plus a little of an arc on the eastern edge. It isn't exactly like some photographs of it, but it does show at least a little detail using filters. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org

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What really amazes me is what is published as to what can be expected in viewing with various sized scopes & what is actually possible , being much more than stated , from my personal experience . I guess the authors must not have readily available sky conditions that we have here in the southwest . ???

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Most of the authors I have read vary quite a bit on exactly how they describe what it takes to see detail in M33. Many indicate the aperture "threshold" for significant detail to be around five or six inches for the galaxy, so in an 8 inch, some spiral detail should be visible (and is often reported with that aperture under dark sky conditions). The venerable Walter Scott Houston in DEEP SKY WONDERS wrote:, "One night in an 8-inch, a congested mass of bright patches was seen superimposed on an overall spiral pattern.", so it was clear that he saw the structure. Unfortunately, the Night Sky Observer's Guide does not mention this, as with M33 (as in some other objects), the descriptions tend to be somewhat pessimistic (the "large scope bias"). One thing to always remember is that even slight skyglow can wipe out much of this detail, so somewhat pessimistic descriptions are understandable. Also, the object has a sort of "sweet spot" range of powers where its detail becomes more noticeable. Those who don't hit that range or spend only a little time on the object tend to just see a large low surface brightness glow and, being disappointed, move on to something else. It takes a little practice to tease out the detail in M33, so one should not give up on it, even if the first view of it tends to be somewhat disappointing. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org

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Book after book & magazine after magazine article lead one to believe that it takes 10 to 12 to 16 inches of aperture to see these details. What do you think ?

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I read in a popular book that the Crescent Nebula in Cygnus (NGC 6888) requires a 17" Dob, and even then, is scarcely visible and "not worth the effort."

Expecting little, I set out to find it with my 12.5" Dob from my dark site (brown/black). In a matter of seconds I located it. Holy Mackerel! It was spectacular! An OIII filter gave me views comparable to the photos I've seen, with nearly the whole ellipse visible and masses of filamentary detail inside. I was mesmerized for many minutes by this wonder.

Then I turned to my 8" SCT. While dimmer and somewhat less detailed, the Crescent was still obvious and detailed. A terrific catch that the book told me I should just forget without massive aperture.

Just goes to show that what somebody said is never the last word.

-- Tim
Colorado

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Wonder what book that was? I have seen a little of the Crescent in my 100mm f/6 using the DGM Optics NPB filter, although it is considerably better seen in my 9.25 inch SCT using either the NPB or the OIII filters. Without a filter it can be a little hard to tease out of the sky background, but an 8 inch certainly should show at least a hint of it under a dark sky. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org

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