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Re: [APML] saturn occ. time exp.
What I did to prepare was, using TheSky, to set the time (Data->Site
Information menu) to be just a few minutes before the occultation was to
occur, use the object finder to find and center Saturn and using the
Utility tab on the Object Information dialog clicked on the "Lock On"
button. Then, using the icon bar that controls the passage of time you
can step forward and back in minute intervals for a nice view of where
Saturn will be occulted and revealed. Unfortunately, the detail of the
Moon is less than I would like buts its enough to give you a good idea
of the features that will be in the field of view along with Saturn
(however, the Moon will go white/gray if you zoom in too much). You can
also lock on the Moon (though there are times when I can't get it to
lock).
Marios, I just checked your web site and noticed the lat. and long.
coordinates you provide. I put them into TheSky and got a view of what
you will be seeing. It states (and shows) that the Moon's phase is
99.94%. Thats about as full as you can get so no help from a dark
terminator.
I also checked the occultation following that. For those in most of the
US the December occultation (12/28/01 around 12:13am PST) we will have a
95.59% phase which places the terminater near the limb where Saturn will
be occulted. This means that there should be a narrow strip of lunar
surface, near Saturn's point of disappearence, whose brightness will be
a good match for Saturn and will not be over exposed with an exposure
time chosen for Saturn.
-Glenn
Adam Stuart wrote:
> Speaking of The Sky, can you give me a few pointers in
> order to be able to step-through the path that saturn
> takes in the sky on November 30th? How do I view the
> moon and saturn during a time sequence in enough
> detail? Do you just zoom-in on the screen?
>
> Thanks.
>
> ADAM
> --- Glenn Graham <glenng@synopsys.com> wrote:
> > Very true about the difference in "good" exposure
> > times for Moon and
> > Saturn. Along the edge of the Moon's terminator you
> > can use a good
> > Saturn exposure time and still see some Lunar
> > detail. Where are you
> > located? I would check, using a program like "The
> > Sky", to see what path
> > Saturn will take with respect to the Moon and its
> > terminator. If Saturn
> > passes near that point before or after it gets
> > occulted, that might be
> > your best bet to get a pleasing photo. You can
> > correct for some of the
> > over/under exposure afterwards if you scan and
> > process the photo.
> >
> > I got a nice video of September occultation using an
> > STV camera. I have
> > a sped up version (every 100th frame) at:
> >
> > http://home1.gte.net/res0jwg1/astronomy/index.htm
> >
> > It might also give you a feel for the difference in
> > brightness you will
> > have to deal with.
> >
> > Good luck,
> > -Glenn
> >
> >
> > Bobby Middleton wrote:
> >
> > > I'd suggest that you plan to use a high total
> > focal length for this.
> > > Eyepiece projection is one way if you have the
> > projection tubes. At
> > > short focal lengths you will be mis-matched on
> > your exposures. Either
> > > the moon will be over-exposed or Sat will be
> > under-exposed. High
> > > magnification at long fl's will get the two
> > objects close to correct
> > > exposures. If you can design your system to get
> > you 1/2 to 1 sec
> > > exposures that will be best. Use the hat-trick for
> > your shutter to
> > > minimize vibrations For your instrument, an
> > 16-18mm eyepiece with a
> > > 120mm projection distance will calculate at 1/2
> > sec exposure for a 200
> > > speed film; 1 second for 100 speed film.Bobby
> > Middleton
> > > "To think that the eye could evolve by natural
> > > selection seems I freely confess absurd in the
> > > highest possible degree" CHARLES DARWIN
> > > http://www.koyote.com/users/bobm/astro1.htm
> > >
> > > ----- Original Message -----
> > > From: Marios
> > > To: astro-photo@seds.org
> > > Sent: Thursday, November 01, 2001 7:08 AM
> > > Subject: [APML] saturn occ. time exp.
> > > Hi friends, I would like some advises for
> > time exposures
> > > for the Saturn Occultaion on the 3rd of
> > November (this
> > > Saturday) I will be shooting Prime Focus with
> > an 8" f/5
> > > F1000 Newtonian telescope. I will mount the
> > camera on the 2"
> > > focuser.Shall I use a fast film (800 ISO?) or
> > a slower? What
> > > would be the time exposures? Thank
> > > you. Marios.www.CyprusAstronomy.com
> > >
> >
> >
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