6
So, once you’ve identified an object you’d like to observe
from the star chart, loosen the azimuth and altitude lock bolts
so the telescope moves freely. Look through the finder scope
and move the main telescope to the part of the sky where the
object should lie and see if you can see it in the finder. You
may have to sweep the telescope side to side or up and down
a bit until you spot it. You can tighten the altitude lock knob
and rotate the altitude micro-motion knob to move the tele-
scope slowly up or down. Note that this knob has a limited
range of movement. If you reach the end of travel, loosen the
altitude lock bolt and rotate the knob back a few turns, then
tighten the lock bolt again.
Center the object on the crosshairs of the finder scope, then
tighten the azimuth and altitude lock bolts. Look into the tele-
scope eyepiece. The object should be there. If it isn’t, or if the
object is too faint to see with the finder scope, use it to aim the
telescope to the approximate position where the object ought
to be, then sweep the area in small increments with the tele-
scope while looking through the eyepiece.
The Moon
Our nearest celestial neighbor, the Moon, is the easiest and
yet one of the most interesting subjects to observe with your
new telescope. The best time to look is when the Moon is in
a partial phase, not when it is full or nearly full. The shadows
cast along the “terminator,” the border between the lit part of
the surface and the shadow, help bring out the relief and
detail of craters, mountains, and other features. You may
want to try using higher magnifications to see even smaller
detail.
The Planets
The major planets—Venus, Mars, Jupiter, and Saturn—are
the brightest objects visible in the night sky after the Moon.
While the positions of the stars remain fixed relative to each
other, the positions of the planets are constantly changing.
Some daily newspapers, the magazines
Sky & Telescope and
Astronomy, and Abrams Planetarium’s Sky Calendar will tell you
the location of the planets in the sky and the times they are visi-
ble. Since planets are quite small, optional high-power
eyepieces are recommended, and often needed, for detailed
observations.
JUPITER The largest planet, Jupiter, is a great subject for the
SpaceProbe 3". You can see the disk of the giant planet and
watch the ever-changing positions of its four largest moons,
Io, Callisto, Europa, and Ganymede. Higher-power eyepieces
should bring out the cloud bands and perhaps even the Great
Red Spot (which has faded in recent years).
SATURN The ringed planet is a breathtaking sight. The tilt of
the rings relative to our line of sight varies over a period of
many years. Sometimes they are oriented edge-on and are
entirely invisible, as they were briefly in 1995! At other times,
they are broadside and easily seen as giant “ears” on each
side of Saturn’s disk. A steady night is necessary for a good
view. You will probably see a bright “star” close by, which is
Saturn’s brightest moon, Titan.
VENUS At its brightest, Venus is the most luminous object in
the sky after the Sun and the Moon. Ironically, it will appear
as a thin crescent when it is brightest. It never strays very far
from the morning or evening horizon, being close to the Sun
in its orbit. Sometimes Venus is even visible to the naked eye
during full daylight! No surface markings can be seen on
Venus, as it is always covered with dense clouds.
MARS The red planet makes its closest approach to Earth
every two years (March 1997, April 1999). During close
approaches you’ll see a red disk, and may be able to see the
polar ice cap. To see surface detail on Mars, you will need a
high-power eyepiece and a very steady night!
The Stars
Stars will appear like twinkling points of light. Even very pow-
erful telescopes cannot magnify stars to appear as more than
points of light. You can, however, enjoy the different colors of
the stars and locate many double and multiple star systems.
The famous “Double-Double” in Lyra and the striking color
contrast of the double star Alberio in Cygnus are favorites.
Deep-Sky Objects
Under dark skies, you can observe fascinating deep-sky
objects, including emission and reflection nebulas, open and
globular star clusters, and galaxies in a variety of shapes and
sizes. Many of the objects will appear as faint smudges, but
with persistent study more detail can usually be teased out.
Don’t expect these objects to appear like the photographs in
magazines; our eyes are not sensitive enough to see much
color in celestial objects, except for a few of the brightest ones.
Consult a planisphere, observing guide, or star atlas to find out
what deep-sky objects are well placed for viewing (as high
overhead as possible) at the date and time you are observing.
7. Collimating the Optics
(Aligning the Mirrors)
The telescope’s primary and secondary mirrors have been
collimated at the factory and locked into place. You should not
have to adjust them unless they were knocked out of align-
ment during shipment or bounced around in your vehicle
during transport. By doing a simple star test, you can deter-
mine whether your telescope needs to be collimated.
Star Testing Your Telescope
With the telescope cooled to the outdoor temperature, center
a bright star in the field of view of a high-power eyepiece. Now,
defocus the star image until it becomes a large circle of light
filling about one-tenth of the field of view. A black “hole” will
appear in the circle, like a hole in a doughnut; that’s the shad-
ow of the secondary mirror. The hole will be exactly centered
in the “doughnut” if the telescope is in proper collimation. If the
hole is off-center, the telescope is not properly collimated and
some adjusting of the mirrors will be necessary.
Remove the eyepiece and look directly through the focuser at
the secondary (diagonal) mirror. The reflection of the primary
mirror should be precisely centered in the secondary mirror
