Re: Occulting Eyepiece, observing Phobos and Deimos


"Dennis Woos" <dpwoos@xxxxxxxxx> wrote in message
news:13gcgt9l1kgtqf6@xxxxxxxxxxxxxxxxxxxxx
SNIP> Now, has anybody here ever observed either of Mars' moons? Does
anybody have any tips on observing them?


Here is a post I made during the August 03 approach.



"After the visitors and most members had left our Mars openhouse at clubs
observatory two of us spent the early morning hours looking for the two
moons rather than surface detail. The nearby 9.95 magnitude star
(TYC6386-00334-1), Sky and Telescope's Mars moon java applet and TMB
SuperMono's were critical to the hunt. All observations were made sitting
down, one must be comfortable and patient to wait for the moment of good
seeing. The sky conditions were mostly clear with some thin clouds, no wind
and high humidity. After 5UT the seeing improved to being variable from a 7
to nearly a 9. I had my AP130F6 and he a 13" Dob with a good galaxy
mirror.

After trying for a half hour to 45 minutes looking unsuccessfully for Demos
I switched to the 13" Dob. I put in my 4mm TMB SuperMono and was able to
find Demos after about 15minutes of looking at 6:10 UT. Had to keep Mars
outside of the FOV though. It was not visible in the other observers 4.8
Nagler due to excessive light scattering. The dob had not been set up on
it's platform but smooth hand tracking keeping Mars on the edge of the field
stop was possible or 30 to 40 seconds before more rapid motion was needed to
reposition the planet. The nearby star made for a convenient estimator for
the magnitude and position of Demos. With the visual field now know I went
looking for it again with the AP130 and after another half hour of looking
was able to get it using either a 4 or 5mm TMB SuperMono straight through
(no barlow or diagonal). Demos was frequently not visible for periods of
time as the transparency of sky conditions varied. However, when visible it
was visible 100% of the time.

The sighting in the AP130 was confirmed by the other observer and we bounced
back and forth between the two scopes with our observations after that. The
first observation was about 1 hour before greatest elongation (7:12UT per
S&T). A driven scope sure makes it easier to keep Mars just outside and
adjusted it north or south on the field stop. I was not able to get Demos
with my binoviewer and TMB 8 or 10mm eyepieces with or without a barlow.
After Demos we started looking for Phobos as it started to approach greatest
elongation. I had one clear view at 6:50 UT for approximately 1 minute of
the star, Demos and Phobos in their expected positions using the AP130 and
TMB 5mm. This was approximate 1hr before maximum elongation (7:53 per S&T).
The sighting was not confirmed by the second observer nor repeated by myself
over the next hour, although Demos was frequently visible. I packed up at
4am since sky transparency had fallen off and Demos became less frequently
visible.

So did we see the moons in a 5.1" scope? Demos for sure, many times, and
it's motion relative to Mars and Mar's motion relative to the star were
obvious. I believe I saw Phobos as it was clear and steady for a short
period of time."





.

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