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Finally!....

parallaxerr

By parallaxerr
in Observing - Discussion

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parallaxerr

parallaxerr

Posted
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....Skies good enough to put my recently acquired C8 Evo SCT to use.

I set up last night not really believing that I'd be out for long, only to find the seeing the best I've seen this year. Target was the moon with the C8, after cooling for about an hour I quickly checked and adjusted collimation which was a touch out, probably as a result of the trip to the recent SWAG star party.

I went straight for the Appenines and Mons Hadley, a region that has really caught my attention of late. The C8 is still relatively new to me so I had to experiment with EPs to find the right balance between power and manual tracking ability on the Altair Sabre Alt/Az mount. Turns out my 10mm Vixen SLV was just right, giving a mag of circa x200. Being only 50° AFOV, the image was drifting across the view quite quickly but could be viewed to the very edge of the FOV due to being nice and flat.

What incredible detail that I've never seen before, surfarce rilles, small craters and ejecta from nearby craters were all clear as day with excellent contrast. Studying the terminator in the same region and I saw the detached detail where the sun was just catching the top of craters not yet fully illuminated, beautiful.

I had spent the best part of an hour on Luna when I noticed Jupiter rising in the South East, low above the rooftops. I targetted Jupiter at the recent star party and, quite frankly, it left me somewhat dissapointed, the seeing turning it into a washed out blob. Not so last night, instantly I could see 3 distinct bands and a sharp cut-off where the North polar region started. Moments of excellent seeing brought out detail in the two main bands giving hints of visible storms/vortices.

As I observed, I noticed Io approaching and a quick check on Stellarium confirmed there was an impending transition. I was pretty tired by this point but couldn't resist holding out for Io's transit shadow. I didn't have to wait long, the shadow seemed to lead Io onto the disc and furthermore, I could still make Io out during transit!

All in all a real quality observing session, lasting about 2.5hrs in total. The C8 shone at Lunar and planetary, more so than I thought it ever could. I thought my F11 frac was pretty good on these targets but the SCT pulled it's pants down in no uncertain terms. Mojo fully restored after months of poor seeing, nights like last night make the wait worth while :)

Lessons learned:

1. Manually tracking in Alt/Az at high mag is not easy. It took some time to get the balance and tension right on both axes and to get the right feel for nudging, but I got there in the end. I want to try some wider FOV EPs.

2. Focusing the SCT was not as nice as a frac, far too coarse. I think a crayford will find it's way on to the back before too long!

 

 

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Knighty2112

Knighty2112

Posted
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Nice report Jon. Glad the new mount seems to be going OK. I was looking at the same region of the moon last night too, especially the Alpine Valley. I was trying to make out the smaller fault line in the middle of the valley, but seeing (and I think aperture of my 4SE Mak) wouldn't allow it. Lots of interesting details in this area that can keep you captive at the EP for hours. 

I looked at Jupiter too later on in the evening (around 23:30) as Io was crossing its face. Could make out the shadow OK when seeing was steady. Sounds like you had much better seeing than here. I've been also managing to track Vesta over the last few nights too on the 6/8SE Goto mount, so well chuffed with the new setup to. :) 

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John

John

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Great 1st light report !

I was observing similar targets to you with similar results :icon_biggrin:

I thought the seeing when Jupiter was up was OK but I have seen it better. The Io transit was very clear though.

I do find wide field eyepieces very useful for manual tracking with alt-az mounts. Unusually though last night I had my refractor on a tracking EQ mount so could relax and enjoy the views :icon_biggrin:

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cloudsweeper

cloudsweeper

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A great session, Jon!  My 8SE gives wonderful views of the Moon too.  Interesting that you saw the shadow and the moon Io itself - I'll have to look out for that.

The focusing can be made a little finer by pushing something onto the focuser knob - I use a wide tyre off an old toy truck; Gus recommends a Marmite jar lid.  Both very effective!

Doug.

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parallaxerr

parallaxerr

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Gus actually gave me a foam rubber ring to go over the focuser knob which helps, but I still find the action too coarse. I'll persevere before shelling out on a focuser, but I'm the type that will fold and buy one anyway!

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