Observing Deep Sky Objects - Celestron AstroMaster LT Instruction Manual

• The best time to observe the Sun is in the early morning or late afternoon when the air is cooler.
• To center the Sun without looking into the eyepiece, watch the shadow of the telescope tube until
it forms a circular shadow.

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.
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 of the color seen in long exposure photographs. Instead,
they appear black and white. 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.
Star Hopping
One convenient way to find deep-sky objects is by star hopping. Star hopping is done by using bright stars
to "guide" you to an object. For successful star hopping, it is helpful to know the field of view of you tele-
scope. If you're using the standard 20mm eyepiece with the AstroMaster LT telescope, your field of view is
approximately 1º. If you know an object is 3º away from your present location, then you just need to move 3
fields of view. If you're using another eyepiece, then consult the section on determining field of view. Listed
below are directions for locating two popular objects.
The Andromeda Galaxy (Figure 5-1), also known as M31, is an easy target. To find M31:
1. Locate the constellation of
Pegasus, a large square visible
in the fall (in the eastern
sky, moving toward the point
overhead) and winter
months (overhead, moving
toward the west).
2. Start at the star in the northeast
corner—Alpha (α) Andromedae.
3. Move northeast approximately
7°. There you will find two stars
of equal brightness—Delta (δ)
and Pi (π) Andromeda—about
3° apart.
4. Continue in the same direction
another 8°. There you will find
two stars—Beta (β) and Mu (µ)
Andromedae— als about 3°
apart.
5. Move 3° northwest—the same
distance between the two stars—
to the Andromeda galaxy.
Figure 5-1
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