The Heartbreak of Dew

Astro log: Nov. 13th, 2009

Equipment: Orion Skyview 6 Deluxe EQ and Celestron Astromaster 76 EQ, using the 32, 25, 15, and 9 mm eyepieces and the ultrablock filter.

New objects observed: dew

Previously observed objects: M31, M32, M42


I had had great hopes for this night - the sky was going to be clear for a long time for the first time in ages, with halfway decent transparency to boot. I went and set up my shelter and scope early in the night, but found that there wasn't a whole lot out that I could look at early on, so I went back inside, leaving my stuff out for later.

When I came back out, I was a bit surprised to find that massive amounts of dew had settled on everything. Still, it wasn't the end of the world. I started looking around, but found that I was having a really hard time finding anything in my finder scope. Then I noticed that I was having a tough time seeing anything at all. Finally I shined my red flashlight on my eyepiece, and saw that it was fogged up. Oh no!

I tried swapping other eyepieces in, but that didn't help. The primary mirror was fine, at least, but I still couldn't see anything. Eventually I noticed that the secondary mirror was fogged up, so I packed everything up and took it back into the garage. I pointed the 6" upside down to dry out and left the lens case open so that could fully dry out as well. I took the 3" out for a spin for a while and was able to see M31 (but not M32) and M42, but not with the same detail as with the 6" of course. I am not, however, sure how much of the difference was from the size of the mirrors and how much was from any dewing on the 3".

After a while, I brought the 6" back out and was able to observe M31, M32, and M42 briefly, but it dewed up again within a few minutes and I gave up. I have begun researching anti-dewing solutions and will try them out next time the weather permits observation.