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The LX200 is mounted on a permanent metal pier bolted to the
concrete floor of the observatory. The observatory floor is a
12-inch thick square concrete pad 15 feet by 15 feet. The
ten-foot Home Dome is also bolted to the concrete floor. This
design is simple and inexpensive but provides little protection
from vibrations being transmitted to the telescope by someone
walking around inside the dome. This was a problem when the
telescope was used visually and is a problem with CCD imaging.
If there is much activity inside the dome when a CCD image is
being exposed, the subsequent vibrations transmitted to the
telescope ruin the CCD image. If one sits comfortably and
quietly in a chair working on the observatory’s computer during
an exposure, no significant vibrations are transmitted to the
telescope. Thus, it is quite possible to use the system while
inside the dome. However, it rapidly gets boring if you want to
take a sequence of 30 one-minute exposures.
To do CCD imaging, I had two choices. I could either sit there
and entertain myself by reading a magazine in the low ambient
light level of the observatory, or I could go inside the house
for 30 to 60 minutes and return when the sequences of exposures
was finished. I had to be careful not to bump the telescope, and
I had to plan for one or two exposures to be ruined while
getting up to exit the observatory.
Going back and forth between the house and observatory during a
long sequence of exposures worked fine for a while. One or two
exposures were ruined, but most of the images in a given
sequence turned out fine. I could be inside doing something
else, but I did get nervous wondering how the images were
turning out and whether the telescope and computer were all
right. I used this technique of going inside for a long sequence
of exposures for a few months, but, because the observatory is
220 feet away from my front door, I rapidly got tired of running
back and forth for frequent checks on the system. The CCD camera
is light tight, and a dew shield placed on the telescope
prevents light coming off the computer screen and light cast by
a small reading light from fogging the exposures. Thus, it was
possible to sit in the observatory and quietly catch up on one’s
reading while taking a long sequence of exposures.
None-the-less, this also got tiring. Not only was it boring to
sit in the observatory reading astronomy magazines, but I also
got cold. Even in Arizona it gets cold in the winter, sometimes
going below freezing. Therefore, I decided to see if I could
automate the observatory to control the telescope and CCD camera
from inside my house, only going outside to start the system up
at the beginning of an evening’s observing run and later going
outside to shut it down at the end of the evening’s work. |
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