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Subject: [M]: OT: OBSERVING Mars and Saturn
From: Todd Gross
Reply To: mapug@shore.net
Date: Thu Aug 14 02:49:21 1997
>Date: Wed, 13 Aug 1997 9:18:22 -0700 (PDT)
>From: Allen Ginzburg <alleng@sco.COM>
>Our Astro club was at Yosemite National Park last weekend at an elevation
>of 7700 feet. One night the seeing was very good. Cassini was easy to
>see in my 10" LX-200 f/10 at the left and right edges where the ring appears
>thick. It was not visible along the thin part of the ring in front of the
>planet. Have you been able to see it along the thin part?
>Also, thanks for the correction on the Mars polar cap. The large dark area
>was indeed Syrtis Major, but I didn't think that Hellas could be that bright.
>There were several other dark features also easily visible.
Hi Allen!
Hellas has apparently been filled with clouds, and that is why it is so
bright. I saw a video from the last
apparition, and it was filled with clouds then too. It appears brighter than
the north polar cap when the cap
shrinks. The south polar cap is not visible apparently because of geometry.
I was fooled too, and corrected.
The Sky and Telescope info (January I think) was very helpful.
As for Cassini, at the current ring tilt..even with a night of very good
seeing, and Cassini easy to hold, it is not visible in front of the planet,
just on the sides. I have seen a picture where, when the ring tilt becomes
steeper, not only is Cassini visible in front, but you can see Saturn's disk
through the gap.
I WAS able to view a bright portion, looking like a ring in itself, at the
edge of the B ring bordering Cassini. I have subsequently found this in
pictures.
I have not seen the Encke division, and am barely discerning the Crepe ring,
but I am going to try a different
tactic on the Crepe next time it is clear and stable.
TO ALL:
While most of these observations are with the 16", often stopped down to
6.4.... the 8" SCT picks up on almost all of it as well.
I believe most LX200s, and Meade scopes, will pick out the Cassini division
this year when skies are steady, last year, it took the best scopes of the
bunch. Still, it's an excellent test to make sure optics are okay. Waiting
for proper seeing conditions can drive you to madness though.
I dont' know if I mentioned it or not.. there has been talk on the list of
observing 9, 12 belts/bands on Jupiter, etc.
This gets confusing since they are different on different sides of the
planet, and different times of the year..and years. What one shoudl strive
for is the ability to pick out the low contrast features - some of the less
contrasty white ovals for instance. Near the Great Red Spot right now are
THREE well definited white ovals passing just south.. there are many more
subtle white ovals, and also some bridges, and blue festoons and such that
can be easily detected with fine optics, on fine nights. My best luck is
with the Televue binoviewer. Best magnification is 200-300x. If the sky
isn't allowing you to go above 200x, it isn't the right night to attempt
this. I have posted a drawing from an excellent night from two weeks ago at:
http://www.weatherman.com (can't remember if I mentioned that already, if I
did, my apologies)
next to it is a CCD image by Paul Laughton which was taken 9 days later,
with many similar features, better contrast due to the CCD processing than
what one woudl see through the ep. Still, I have been able to detect
slightly more than the CCD image with the large scope in fleeting moments of
excellent seeing.
Don't be discouraged if you can't make out as much, it takes patience, and
indeed optics are important. Before shopping for another scope though (if
you are a planetary nut like me) collimate your scope, and assume your
optics are really just fine, and it is the seeing that's a problem. (that is
often the case) Then if you can, compare views through your scope to someone
else's of near EQUAL APERTURE (different nights act differently
"seeing-wise" at various apertures, one night smaller aperture may be
better) to get a better feel.
- Todd
_________________________________
BOSTON TV METEOROLOGIST TODD GROSS
Weather/Astronomy Home Page: http://www.weatherman.com
Administrator, Meade User Group: mapug@shore.net & NE Weather Watcher Mail
List, wxobs-sne@shore.net
IRC Channel Operator: #Weather, #Sciastro (Undernet) // Originator
of the NE.WEATHER newsgroup
_________________________________
Email: toddg@weatherman.com Work Phone# (617)725-0777