Missed the GRS

AA
Subject: Missed the GRS
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From: Anonymous AtWork
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Date: Wed, 28 Jun 2006 12:35:19 -0400
AA
AA In this order? In that case, it must be thermal non-equilibrium. I
AA bring it out, use it and put it away all within an hour or so.

Definitely let the scope acclimate to the outdoor tempeature,
specially if there is a sensible change of tempeartue between the
storage place and the yard. This means if the house is ACed or the
garage is sunbaked, you got to put the scope out early in evening,
like at sunset, to let it cool, or heat!, to the ambient temperature
by nightfall.

AA You should check your collimation (and optics) by doing a star test (use
AA Polaris). This will allow you to precisely align your primary, assuming
AA that everything else is right on, i.e. focuser square, secondary properly
AA positioned/rotated, secondary pointing at center of primary. A 6" f/8 can
AA be off quite a bit and give ok views, but for great views must be pretty
AA much right on. If you made the mirror I suspect that it might not be great,
AA but I certainly don't know that. The star test will tell you what is going
AA on. See, for starters:
AA http://aberrator.astronomy.net/html/...r-testing.html
AA
AA I bought the mirror, so that should be OK. From the link:
AA
AA "If you see a perfect round airy-disc surrounded by concentric well
AA defined rings your scope is definitely collimated."
AA
AA I definitely have not seen that, so I may not be collimated.

Unless the air is steady, or the scope is stabilized, and you got
good eeyesight, you won't see the ideal Airy disc image. That's why
you got the suggestion to collimate with defocused images.

AA As far as the GRS goes, it will not look red, or anything like it, but more
AA like a hole in the band. Join your local astro club, and compare your views
AA to what others are getting.
AA
AA The local astro club is quite a ways from where I live, but I may have
AA to resort to that.

The meeting place or postal address may be a bit far away. There
could be members of that club closer to you whom you can all or email
for assistance. How far is far? That is relative. In Monttana, if the
club is farther than what you'll drive to attend a swinger's parrty,
that's too far. In New York, if you have to take more than two
buses/trains to get to the club, that's too far.

---
þ RoseReader 2.52á P005004


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