Posts Made By: Doug Peterson

Figure 2: Global temperature changes (5-year smoothing) 1860-2005 (Hadley Center, 2008; see Figure 15d). The figure shows also the amount of CO2 in the atmosphere during the same period.

Hands down, Larry Carlino, IMHO. You?

The slope thru the last 6 years looks like .03C per decade, per three government supplied data sets. The real warming took place in the 20th century, maybe 1 degree F--you can't feel that difference with your household AC. Yet the human-induced C02 continues to increase exponentially per the figure in my last post.

Where's the beef?



http://rankexploits.com/musings/2008/gmst-projections-vs-observations/

Anyone know of a source for new or replacement ocular rubber grip rings? I'm mainly looking to restore a 2".

Recently I saw a 14" mirror posted with .999 Strehl and 1/35 wave peak to valley. This ridiculous abuse of specifications must stop. Serious opticians work hard to achieve reasonable tolerances, but some unscrupuous vendors use deception to get you to believe you are getting something transcendental.

A friend, an optical scientist, had a similar mirror from the same vendor. The advertised 1/30 wave peak to valley achieved with magic turned out to be 1/8 wave on his interferometer. Quite a decent mirror. The vendor should have been proud of it.

The movie has the distinction of being the first hollywood flick to deal with interstellar travel. One of my favorites and a classic. Nevermind the MST3k version, it was making fun of a movie that was half the length.

I just read the novel, and it is superior in many ways, far more detailed, quite different from the flick, and is frankly a whole new experience. Raymond F. Jones wrote some interesting stuff, but this may be his best. At points the writing is somewhat poetic, as when he describes a war on a galactic scale where the inconceivable vast energies twist space and time, turning spacemen "into screaming things that will live forever." Thumbs up.

I only have one, but when I get more, what will I call them in the plural?

Most old C90s I have seen have decollimated primaries, and there is no user fix. You can send it to Celestron and it will cost $150 bucks, but after three attempts, I gave up. Very poor service. Didn't get it right and the scopes were covered with greasy paw prints. Finally had to figure out how to do it myself.

You remove the three filler screws from the rear cell.
The next may be hard to visualize without the scope in front of you. The spring clip is a open ring around the baffle tube right next to the mirror surface. It prevents the mirror from falling out. It also is a problem when you stick in the three 6-32 screws and contact the back of the mirror to tilt it: the spring clip prevents the mirror from moving, so you end up distorting the wavefront.

Remove the rubber ring and set screw and thread-off the entire front end. Protect the mirror with a rubber disk cut to lay over it, and pull the spring clip up the baffle tube away from the mirror a fraction of an inch. (An improvement may be to put an O-ring between the mirror and the clip). The mirror is now held only by the 3 silicone blobs on the back side, which you can't see. Now when you advance the screws you can tilt the mirror, you only need to do it a fraction of a turn, so the silicone isn't stressed.

Use a bright star out of focus at lower, then higher powers to center the dark hole of the baffle as seen in the eyepiece. At the highest powers, use the star image in focus and tilt the mirror till no coma. I have done this on three C90s and all of them now have superior optics, razor sharp.

Haven't seen mine yet....

I am suprised at how few people are taking advantage of the opportunity to pay 5 bucks to keep their ad on the front page for 24hrs, or 10 bucks for 60hrs. Each time I have done this I started with a regular ad that didn't sell, but Featuring it does the trick.