Re: [APML]Emission Lines Question and missing Veil

["Bert Katzung" <katzung1@attbi.com>]

Hi Bill:
Sounds like you have the pointing pretty well nailed, so it must be the
film. Try one of the 400 speed films like "old" Supra 400 if you can find it
or Provia F400 slide film. E200 (or Elite Chrome 200) is guaranteed to give
you the best red response and you can always push that  for extra speed.
Glad you enjoyed the website....
Bert

Bert Katzung
katzung1@attbi.com
www.astronomy-images.com

----- Original Message -----
From: "William R. Mattil" <wrmattil@ix.netcom.com>
To: <astro-photo@seds.org>
Sent: Tuesday, September 03, 2002 6:04 PM
Subject: Re: [APML]Emission Lines Question and missing Veil


> 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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