Thursday, December 18, 2003

A Crisp, Clear Night in Boise

This is the first such night that we have had here in Boise in some weeks. I was able to drag out my 8" f/7 reflector for the first time since I obtained an easier to use laser collimator. Unfortunately, the atmosphere was still pretty turbulent (or perhaps those were tube currents inside my telescope).

The temperature contrast was strong enough that I could see the focus of the mirror changing. Over a period of about 30 seconds, the telescope went from perfectly focused to a bit fuzzy, because the temperature was changing the shape of the mirror. Saturn is an especially good target for this sort of change, because you have crisp lines (such as Cassini's Division) that you can see blur.

At 157x (9mm orthoscopic), Saturn was crisp, although somewhat small. The Cassini Division was more gray than black at the ansae (the extreme left and right sides of the rings), and only occasionally popped into view in front and back of the planet. I could see at least one cloud band on the planet itself--a medium brown against a very, very pale yellow body.

At 236x (6mm orthoscopic), everything started to fuzz up, with even the ansae portions of the Cassini Division only appearing briefly as the turbulence calmed down. At 283x (5mm ortho) and 353x (4mm ortho), the image wasn't any worse, just larger.

I used some of the money from the PayPal tip jar (thanks!) to pay for a slightly used Photon Instruments 127mm f/9 achromatic refractor this morning. With a little luck, it should be here next week, when I have a whole week off work.

No comments:

Post a Comment