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16 I ENGLISH
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 telescope. If you’re using the standard 20 mm
eyepiece with the Travel Scope 70, your field of view is approximately 2.5º or so. If you know an object is 3º away from your present
location, then you just need to move a little more than one field 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 16), also known as M31, is an easy target. To find M3:
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 —also about
3° apart.
5. Move 3° northwest—the same distance between the two stars—to the Andromeda galaxy.
Star hopping to the Andromeda Galaxy (M31) is a snap, since all the stars needed to do so are visible to the naked eye.
Fig. 16
Andromeda Galaxy
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