dew problems and Death Valley observing

Bill Feiereisen (wjf@No-Spam)
Sun, 31 Dec 1999 11:01:47 -0800

Last night my backyard offered up some of the best seeing that I seen in
a long time. Jupiter was phenomonal for seconds at a time showing as
much detail in my 8" newtonian as I've ever seen. However, the "seconds
at time" degraded pretty quickly with dew. After a time the scope looked
like it had been sprayed with the garden hose. The eyepieces would dew
over in seconds, but more disturbing was the secondary. It would also
dew over. I think part of it comes from my breath and the dewpoint. I
can fix the eyepiece with a hairdryer, but am wary of warming the
secondary for fear of destroying the temperature adaption of the mirror
and thus the wonderful image quality. Any ideas? ... Bill

ps: Just spent six days camped in the backcountry of Death Valley with
three really good nights. No dew there! It was dark to the horizon in
almost all directions (except Beatty and Trona). I spent hours just
bouncing around from sight to sight. The showcase sights like M42 and
the Pleiades had incredible detail. There was very obvious nebulosity
around all of the bright members of the Pleiades and delicate detail in
M42 that occupied me for quite some time. I picked off a number of
planetaries that have been on my list. We were camped at lat. 36
degrees, 19 minutes and had a direct view of the southern horizon. For a
couple of minutes each evening Canopus would poke its head over the
horizon (dec: -52d, 41m). Big 4WD trucks are great. They carry campers
and telescopes to extremely remote locations and allow fantastic
observing while living in relative comfort. No neighbors for miles. I've
noticed that Annette sometimes gets nervous on the way to our campsites.
You know, locked down in 4wd low range and grinding up the mountain by
some precipitous drop off. Now why would that be? :-)


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