Thursday, January 16, 2014

Second Light

I built a rolling platform for the new telescope this evening from an 1/8" thick piece of steel and four casters.  No pictures (I am already in bed), but it works.  I may want to cross brace it underneath -- 1/8" steel is not quite stiff enough to avoid flexing a bit.  The details are little more complicated than that, but I will discuss them with pictures tomorrow.

But unlike the night before last, I left the telescope out in the cold for about an hour before observing.  Telescope mirrors take a while to cool, even when made of Pyrex.  In the meantime, they go through a number of shapes other than what they are supposed to be.  The results were far more impressive than what I described a couple of days ago!  I saw far more detail on the Moon and on Jupiter, with improved contrast.  (Spend some time understanding what happens to the focus of a parabolic mirror when it is actually a hyperbola or ellipsoid, and you will get some idea of why being exactly right improves contrast.)  Jupiter at 222x had far more detail on it than I can remember.

Then I moved to the Orion Nebula, and I saw some indications that I may not have the collimation exactly right.  Before moving the telescope out, I noticed that one of the truss connectors looked loose, so I tightened the knobs a bit.  But I don't think that they were acutally loose -- but I do think I moved something a little, affecting collimation.  The stars in the Orion Nebula were definitely not crisp pinpoints of light.  I will recollimate tomorrow night, and try again!

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