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Mars Moons - How Challenging



 
 
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Old November 6th 05, 01:05 AM
tmbMike
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Default Mars Moons - How Challenging

I was reading Greg Crinklaws cool observing essay:
http://www.skyhound.com/sh/Focus/Mars/Hall.html

In there Greg quotes The Telescope Handbook and Star Atlas by Neale E.
Howard as follows:

"Certainly the strangest little objects in the whole solar system, the
two moons of Mars will rarely be seen by the amateur unless he
possesses a 16-inch telescope, and then only at favorable oppositions."


The rest of the essay and the general feel I get from reading
miscellaneous sites is that it's not very common to see these two
little moons.

I observe from about an hour north of Anchorage Alaska, seeing is
usually mediocre, cold and fogging problems are common. Mars peaks
about 45 degrees elevation here. I had no plans to even go after the
moons of Mars, until the other night (Nov-1) watching Sinus Sabaeus
transit the planet when Deimos decided to come after me.

I was using a TMB 7" refractor with an AP binoviewer and two 6mm TMB
supermonocentrics for 396x. Seeing was 5/10 with rare moments when
detail would seemingly crystalize over the entire planet disc. (Maybe 2
or 3 times during a couple hours.)

I think it was good luck that led me to Deimos. I've heard there are
specific directions from your center of vision where averted vision is
the strongest. As I would watch the western end of Sinus Sabaeus, I
kept noticing an interloper popping in and out of existence what seemed
a couple mars-widths off the planet to the East. It was obviously right
in a peripheral hot spot in my eye because it would disappear any time
I looked at it.

I had a suspicion as to what I was seeing! I ran into the house, and
messed around with Skytools and confirmed it was Deimos. The house is
about 65 degrees F warmer than my observing chair, so I took my time.
About 1/2 hour later i went out and it took me about another 15 minutes
to re-aquire the moon, Deimos had moved relative to an imaginary line
drawn across Mars equator. These moons must be really racking up the
mileage fast.

I tried shifting Mars out of view and Deimos became quite obvious with
averted vision. Still, I could not lock onto the moon with direct
vision in this fashion.

Now Phobos is what, like 3 times brighter? But I havent managed to see
it yet. The Deimos experience has me checking each night to see what
times Phobos and Deimos will be at their greatest ?elongation? I have
a feeling dimmer Deimos is the easier of the two. It seemed easy to
spot once I aquired it. Seeing conditions have not allowed me to see it
since.

I made a sketch the following day
http://www.scopenews.com/tmb175/mars..._deimos_sm.jpg

175mm is a lot smaller then 16 inches. I'm guessing tools like the
binoviewer and supermonocentric eyepieces are my trump card over Neale
E. Howard. Deimos looked obvious enough that I am sure I could have
seen it in a smaller aperture than I was using.

Mike Clemens

 




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