Re: [APML]Emission Lines Question and missing Veil

["William R. Mattil" <wrmattil@ix.netcom.com>]

Bert Katzung wrote:
> 
> Hi Bill:
> That's puzzling. Are you *really* sure it was in the FOV?

Well, my first thought was that I missed it entirely. But I have
compared the FOV with known targets such as M31, NGC7000 etc and using
The Sky software I have plotted the FOV such that it matches exactly.
Then comparing this to the images I can catagorically tell you that the
bloody :^) thing *should* be there. It isn't. And its not a vignetting
issue because a few images of NGC7000 are very near edge of field and
still very visible.

> At f/1.5 a 30
> minute exposure should certainly put significant image on the film.

So then I am not crazy ?? :^)

> If you
> compare with my (terrible) film image (LE400) at
> http://www.astronomy-images.com/images/Nebulas/veil.6992.htm you can see
> plenty of image at 60 minutes through an IDAS filter at f/4.5 and 30 minutes
> with no filter. Faster film, but your faster optics should easily make up
> for it. As far as emission lines are concerned, most of the Veil is H-alpha
> as far as I know. Visual observers like the OIII filters because you can't
> see much of anything through an H-a filter and there is enough OIII emission
> to make it visible while increasing contrast.

Wouldn't the easiest explanation be that the brightness of the nebula
coupled with the RG100 (The Lagoon wasn't all *that* great ! :^) )
perhaps falling off rapidly in the 600nm region account for this ?

>
> Can you try a faster film or do some fancy calibration of your pointing to
> check this out?

Well the guidescope couldn't see the Veil (I have no OIII filter) But
Epsilon Cygni is well within the FOV of the Schmidt Camera and stars on
the chart "past" the Veil are on the image. So ..... my guess is that I
am in the right place. 

Process of elimination says barring the possibility that I can't read
the Star Charts :^) the film is the only thing left ? And recent testing
by another APML'r tends to indicate that this film does lack a little
Red .....

I believe that my image is centered on 20h45m56s +30d40m10s. There is a
brighter star almost dead center which is 52 Cygni. (approx mag 4) and a
close optical double which is approx mag 8.  Southwest edge is bounded
by SAO 89216, Northeast by GSC 2690:620

BTW - your images are very nice ! .... I'll have to keep trying.

Best Regards

Bill

-- 
William R. Mattil	| Fred Astaire wasn't so great.
wrmattil@ix.netcom.com	| Ginger had to do it all backwards
(972) 399-4106		| and... in high heels.

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