by Bill Arnett
At 6:03 PM -0800 1/29/99, David North wrote:
>We're getting odd steadiness ...
Not so odd, IMHO. We often get steady air when there are high thin cloud like tonight. The sky is ugly, ugly but ...
The Moon was 9/10 for sharpness tonight. The high clouds make the image washed out and ugly but high contrast features were very easy. I won't list my trophies for the night (since they were embarressingly few) but suffice it to say that a more dedicated observer would have had a field day.
I did a little experiment tonight with my dew heater. At its highest setting it puts about 30 watts of heat into my corrector plate. I have often wondered if that would produce my own little pocket of bad seeing right where it would do the most damage. Tonight was a perfect time to test that hypothesis. So when I began the evening with the heater on low (just 3 watts) I took note of the image steadiness. I then cranked it up to the max 30 watts and went inside. When I came back out an hour or so later the image looked just as steady as before. Encouraged, I turned it back down to 3 watts (and pointed the OTA at the ground to prevent any dew; it wasn't a very wet night) and went inside again. After another hour the image was still the same. Conclusion: 30 watts of heat to a 12" SCT corrector does not cause visible problems.