(SNES) Why can't I see it?

[Albireo54@aol.com]

Hi Ernie and everyone,

WOW, that big long thesis I wrote about image and surface brightness 
certainly landed with a resounding THUD! Not a murmer from anyone. Oh well, I 
guess that means it was so very excellent that no one felt they could improve 
upon it - or it was so abominably bad that no one wanted to cause me further 
embarrassment by pointing out how far off base I was!  LOL

Of course, the issue keeps coming up, and will continue to do so - it's one 
of those areas of astronomy open to considerable "interpretation". Ernie 
Evans emailed the FDO mailing list today to question why so many nebulous 
objects, which supposedly are visible in much smaller scopes, have been quite 
INVISIBLE in FDO's 16" and Hanks 20" light buckets.  

(I also enjoyed reading Dave Aucoin's observation reoprt from FDO last 
Saturday about planetaries - also often very tricky to pick out.)

In the case of diffuse reflection and / or emission nebulae, it's been my 
experience that many manufacturers grossly overblow what the average observer 
is likely to be able to see in a given scope. Yes, if you took FDO's 16" 
LX200, relocated it to a desert environment, at an altitude of 7,000 or 8,000 
feet, and that site was 40 or 50 miles from the nearest town - then the 
wonders you would be able to see would be mind boggling.

However, we're talking real world here. Sea level environment (or nearly so), 
terribly changeable weather, high humidity, air pollution, fogs, urban 
sprawl, etc., etc. No optical device used under these conditions can possibly 
perform to its full potential. But these are the conditions that 95% of 
America has to deal with. FDO is just fortunate in that some of the 
conditions are mitigated by its rather remote location. Yes, its skies are 
darker, all the time. But it faces all of the other regional hazards.

A good example of this situation in practice is the Horsehead Nebula in 
Orion. In some parts of the country (described in the ideal, above), this 
faint, low contrast object has been seen in 10" and possibly even 8" scopes. 
Here in RI, even under FDO's dark skies, we had to combine all of the 16's 
power with our own years of observing experience to spot this elusive object. 
And our experience has been similar with other famous DSOs: the Veil Nebula, 
the Helix planetary, and many others.

So I always look at ads in astronomy magazines with a rather jaded eye. 
Theory is one thing, actual observing under real world conditions is quite 
another!

Doug Stewart
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