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Archive for January, 2010

On Saturday, Jan 16, I was able to do some relatively quick testing of the new (to me) C9.25 SCT on a new – really new – DoubleStar mount from Universal Astronomics. The set up looked like this with the SV80S  sharing the mount.

My first targets were M35, M42, Castor, M102, Owl Cluster, and Iota Cassiopeia. My big concern was that when sun hit the corrector plate at an angle I could see something in the plate. Whatever it was – I later successfully cleaned it with very gentle swipes – it had absolutely no impact on performance.

I was trying compare performance to a C8, but dew interfered – and there was a  playoff game on – so I never did get a good handle on how the 9.25 compared to the C*. My first impression was it was significantly brighter with more contrast. But I don’t trust that impression and it was distorted somewhat simply by the C* having a longer focal length so that with the same eyepiece it gave more magnification.  I’ll have to runt he two side by side on this mount to get a real comparison.

Meanwhile, after the game I came back out and was surprised to find the clouds hadn’t shut me down, so I moved the scope into the observatory. I wanted to see if the DoubleStar mount would work in there – and use the scope some more.  This time my targets were M42, M35 and its faint companion, M1, M37, M26, M38 and smaller companion, and Algieba – then the clouds came in. Again, I was very impressed with the C9.25 performance, especially on M1. I was also quite surprised that I could even use the DoubleStar in the Observatory. It didn’t jam me up against the dome as the Voyager mount tends to do. BUT . . . and this is important – it is almost too wide for the dome’s slot. That is, for the two-side-by-side telescopes to work in there you need to rotate the dome more often than I like because while they can both “see” through the slot, there isn’t much room left over.

Bottom line – the C9.25 is fine, but I still want to do a comparison with a C8 because I suspect it is not worth the extra cost or extra weight. The DoubleStar mount made it easy to point both telescopes at the same object and performed well, but there are some things I have to learn about it. I think it can perform better if I take more time to balance it and play with the various controls. But it will get a lot of use. I think this set-up will be my personal observing choice when on the Observing Deck. In the Observatory I think the new/used LX10 will reign.

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Boy I keep learning about observing! It’s just amazing how much I don’t know. Like this morning I learned that fogged up eyepiece – usually a major irritation – can be good. no kidding.

I usually have difficulty getting a good, clean split of Izar, a beautiful double star in Bootes.  But this morning – with 16 degree temperatures and average seeing – I suddenly had a perfect view – because I had accidentally fogged the eyepiece!

This may be old hat to veteran double star observers, but for me, fogging an eyepiece is just irritating and I always do what I can to get rid of the haze immediately. But I was using an 8-inch SCT with a 9mm Nagler and I didn’t have my dew gun handy, so I continued to look after I had fogged the eyepiece and suddenly all the dazzle was gone and I saw two perfectly round, well-separated stars, the blue one much smaller.

This makes sense to me because I have observed bright double stars in twilight before – but I have never read anything (and I’ve got two good books on double star observing alone) that said “hey, try breathing on your eyepiece!”
That said, my real goal this morning was to test – once more – the idea of using the AT Voyager mount head on my pier int he observatory. I’d tried this before, but not with the 8-inch SCT – the much-used Celestron I acquired recently.  So I tried it and it seemed to work fine, though I felt it was starting to strain the head which is, in theory, good up to 20 pounds. That aside, what I learned after about half an hour was that it was just plain uncomfortable. Once again I was getting jammed up against the dome. I could fit, but not well, and the stool I needed didn’t match my little rolling, spinning office chair for comfort. So I spent about five minutes changing over to the Universal Astronomics T-Mount. Much better! Easily as stable, if not a bit more so, and much, much more comfortable. The many ways this mount can bend just means I can always find a comfortable way to  look where I want to look, even while within the confines of the little dome.

Bottom line. I think the Voyager mount is best for smaller stuff. I’m going to return it to the tripod, play with it and the Vixen PortaMount, then sell one of them.

Grabbed this from S&T IS utility - depects what I saw this morning.

The SCT continues to please me. My first look this morning was at Saturn and with a 24mm Panoptic I pretty quickly detected four moons. With a 13mm Nagler I saw five. That’s as many as I have ever seen with any scope. I made a quick sketch, then checked it against the JS utility for Saturn’s moons that Sky and Telescope has online. What they showed is what I saw. (The chart here is taken from thatutility.)

Mars map from S&T JS utility shows what was visible about the time I was observing this morning. (Of course there's much more detail here then I saw!}

Encouraged by this I went on to Mars where I made another quick sketch indicating the north polar cap – very obvious – and some less obvious blobs of olive drab on orange. Again, my little sketch pretty much matched what the S&T utility map of Mars showed for that time frame.

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