10
used to clean the exposed lenses of your eyepieces or finder
scope. Never use regular glass cleaner or cleaning fluid
designed for eyeglasses. Before cleaning with fluid and tissue,
however, blow any loose particles off the lens with a blower
bulb or compressed air. Then apply some cleaning fluid to a
tissue, never directly on the optics. Wipe the lens gently in a
circular motion, then remove any excess fluid with a fresh lens
tissue. Oily fingerprints and smudges may be removed using
this method. Use caution; rubbing too hard may scratch the
lens. On larger lenses, clean only a small area at a time, using
a fresh lens tissue on each area. Never reuse tissues.
Cleaning Mirrors
You should not have to clean your telescope’s mirrors very
often; normally once every few years. Covering your tele-
scope when it is not in use will prevent dust from
accumulating on the mirrors. Improper cleaning can scratch
mirror coatings, so the fewer times you have to clean the mir-
rors, the better. Small specks of dust or flecks of paint have
virtually no effect on the visual performance of the telescope.
The large primary mirror and the elliptical secondary mirror of
your telescope are front-surface aluminized and overcoated
with hard silicon monoxide, which prevents the aluminum from
oxidizing. These coatings normally last through many, many
years of use before requiring recoating (which is easily done).
To clean the secondary mirror, remove it from the secondary
mirror cell. Handle it carefully by the edges only; do not touch
the mirror surface. Then follow the same procedure described
below for cleaning the primary mirror.
To clean the primary mirror, carefully remove the mirror cell from
the telescope. Do not attempt to remove the mirror from the
cell—it has been secured in place by both clamps and adhe-
sive. Be careful not to touch the front surface of the mirror with
your fingers! Set the mirror on a clean, soft towel. Fill a clean
sink, free of abrasive cleanser, with room-temperature water, a
few drops of liquid dishwashing detergent, and if possible, a
capful of rubbing alcohol. Submerge the mirror (aluminized face
up) in the water and let it soak for several minutes (or hours if
it’s a very dirty mirror). Wipe the mirror under water with clean
cotton balls, using extremely light pressure and stroking in
straight lines across the surface. Use one ball for each wipe
across the mirror. Then rinse the mirror under a stream of luke-
warm water. Any particles on the surface can be swabbed
gently with a series of clean cotton balls, each used just one
time. Dry the mirror in a stream of air (a “blower bulb” works
great), or remove any stray drops of water with the corner of a
paper towel. Water will run off a clean surface. Dry the cell and
exposed surfaces with a towel. Cover the mirror surface with
Kleenex, and leave the entire assembly in a warm area until it
is completely dry before reassembling the telescope.
9. Specifications
Primary mirror diameter: 4.5" (114mm)
Focal length: 900mm
Focal ratio: f/7.9
Eyepieces: 25mm and 9mm Kellner, fully coated, 1.25"
Magnification: 36x (with 25mm eyepiece), 100x (with 9mm
eyepiece)
Finder scope: 6x magnification, 30mm aperture
Mount: German-type equatorial
Figure 2
Big Dipper
(in Ursa Major)
Little Dipper
(in Ursa Minor)
N.C.P.
Pointer Stars
Polaris
Cassiopeia
To find Polaris in the night sky, look north and find the Big Dipper. Extend an imaginary line from the two “Pointer Stars” in
the bowl of the Big Dipper. Go about five times the distance between those stars and you’ll reach Polaris, which lies within
1° of the north celestial pole (NCP).
