17
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b
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e
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r
r
v
v
i
i
n
n
g
g
D
D
e
e
e
e
p
p
-
-
S
S
k
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y
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O
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b
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j
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c
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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 telescope. If
you’re using the standard 20 mm eyepiece with the PowerSeeker telescope, your field of view is approximately 1.4º
or so. If you know an object is 3º away from your present location, then you just need to move about two 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 (
D
) Andromedae.
3.
Move northeast approximately 7°. There you will find two stars of equal brightness—Delta (
G
) and Pi (
S
)
Andromeda—about 3° apart.
4.
Continue in the same direction another 8°. There you will find two stars—Beta (
E
) and Mu (
P
) Andromedae—
also about 3° apart.
5.
Move 3° northwest—the same distance between the two stars—to the Andromeda galaxy.
Figure 5-1
