Celestron C4.5 User Manual

Observing Deep-Sky
Objects
Deep-sky objects are simply those objects outside the boundaries of our solar
system. They include star clusters, planetary nebulae, diffuse nebulae,
double stars and other galaxies outside our own Milky Way. Unlike the Sun,
Moon, and five major planets, most deep sky objects are not visible to the
naked eye. Finding them requires using your setting circles or star hopping
to them. Most deep-sky objects have a large angular size. Therefore, low-to-
moderate power is all you need to see them. Visually, they are too faint to
reveal any color seen in long exposure photographs. Instead, they have a
black and white appearance. And, because of their low surface brightness,
they should be observed from a dark sky location. Light pollution around
large urban areas washes out most nebulae making them difficult, if not
impossible, to observe. Light Pollution Reduction filters help reduce the
background sky brightness, thus increasing contrast.
Using the Setting Circles
Once the setting circles are aligned you can use them to find any objects with
known coordinates.
1. Select an object to observe. Use a seasonal star chart or planisphere to
make sure the object you chose is above the horizon. As you become
more familiar with the night sky, this will no longer be necessary.
2. Look up the coordinates in an atlas or reference book.
3. Move the telescope in declination until the indicator is pointing at the
correct declination coordinate.
4. Move the telescope in R.A. until the indicator points to the correct
coordinate (do NOT move the R.A. circle). The telescope will track in
R.A. as long as the clock drive is operating and the R.A. clamp is in the
locked position.
5. Look through the finder to see if you have located the object.
6. Center the object in the finder.
7. Look in the main optics using a low power eyepiece; the object should be
there.
8. Repeat the process for each object observed throughout the observing
session.
You may not be able to see fainter objects in the finder. When this happens,
gradually sweep the telescope around until the object is visible.
The declination setting circle is scaled in degrees while the R.A. setting circle
is incremented in minutes with a marker every tenth minute. As a result, the
setting circles will get you close to your target, but not directly on it. Also,
the accuracy of your polar alignment will also affect how accurately your
setting circles read.
At the end of this manual there is a list of deep-sky objects well within reach
of your Celestron C4.5 telescope.
Celestial Observing © 35

Celestron C4.5 Specifications

General

Brand	Celestron
Model	C4.5
Category	Telescope
Language	English