[AZ-Observing] First light on Mars, sort of.

I'm in the middle of reworking my main scope (10" f4.5 dob) to get
better images. I've had the scope for a decade, but I've never been
really pleased with the image quality at higher powers. 

So far I have replaced the secondary with a smaller much higher
quality one, a protostar quartz 2.14" m.a. piece. Originally I had an
unknown brand 2.6" m.a. diagonal.

I also purchesed eyepieces especially for planets, a 7 mm and a 6 mm
UO standard othoscopics. My previous high power eyepiece was a
combination of at 17 mm TeleVue plossl and 2.5x Televue barlow. 

Last night and this morning where the first real test of the scope
with these changes, and the results where impressive.

Star images where much improved, though still not a good as I'd like,
but some of that may be seeing related. Jupiter didn't show much
improvement, but it was rather low over my neighbors house and was
too low to see once the scope cooled for a while.

I left the scope out overnight (with caps on the ends, of course) and
got up at 4:50 am to see Mars. 

I have to provide some background to explain my results on Mars. I've
been observing with a handful of scopes for a couple of decades. But
I've almost exclusively a deep sky observer. Part of the reason for
this is that I haven't had a scope that is very well suited to
planets. I've always been even less impressed with Mars than most
planets. I haven't really looked at Mars much and never really saw
much. Maybe the polar cap and a hazy ill defined dark patch, but
really not more than that. 

So I am generally unimpressed with Mars and am not at all an
experienced planet observer.

But even my inexperienced eye was able to see the best view I've ever
had of Mars in my own telescopes. 

The seeing was acceptable. The defocused image of Mars seemed as if
it had water flowing across it, but this "flow" appeared laminar
rather than turbulent. Mars focused up well, and the image was crisp
with good contrast with both the 7mm and 5mm orthos. 

Observing during twilight was very comfortable and glare free. There
were a few scattered clouds but the sky was transparent around Mars. 

The polar cap was very easily visible and the disk was very obviously
not quite full. 

There may (or may not) have been a dark line at the edge of the polar
cap. This may have been an illusion caused by the large contrast
difference between the cap and rest of the disk.

North of the cap was a brighter area and north of that was a broad
ill defined low contrast dark patch.

Further North was brighter, then a a dark elongated patch. My
observing notes describe a V shaped snake like feature. 

It is very apparent from using Mars Observer II from S&T that this
snake like feature was sinus sabaeus and sinus meridiani. 

Tom Polakis coincidently posted a web cam pic the previous day that
was close to what I saw at
http://www.psiaz.com/polakis/videoastro/20030626/mars2a.jpg. My view
was very close in contrast, and the features I saw clearly were close
to this view, but rotated a bit.

For fleeting moments, I glimpsed more details than his pic shows,
though not long enough to sketch or describe. 

I still have more work to do on the scope. I think I could have
tweaked collimation a bit more. I am replacing the primary as well. I
may replace it now with a decent but not premium quality mirror, then
ship out the current mirror for refiguring to someone who makes very
good optics.

The image of Mars held up pretty well with about 170x (7mm) and 240x
(5 mm). It didn't hold up to ridiculous power (7mm w/2.5x barlow),
but neither the seeing nor my main mirror were really up to that. The
ridiculous power was more humorous experiment rather than serious
test. 

But I am very pleased with the improvements so far and can finally
start to see why people make a big deal about Mars. 


Joe Larkin

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