Orion 9964 instruction manual Light Pollution, Tracking Celestial Objects, Eyepiece Selection

a star is - the brighter a star is, the lower its magnitude will be. A good star to remember for this is Megrez (mag. 3.4), which is the star in the “Big Dipper” connecting the handle to the “dipper” (Figure 8). If you cannot see Megrez, then you have fog, haze, clouds, smog, or other conditions (such as light pollution) which are hindering your viewing.

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2.4 1.7 3.4 2.

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Figure 8. Megrez connects the Big Dipper’s handle to it's “pan”. If you can not see Megrez (a 3.4 mag star) then viewing conditions are poor.

Light Pollution

Most of us live where city lights interfere with our view of the heavens. As our metropolitan areas have become more developed, the scourge of light pollution has spread, washing out many stars and nonstellar celestial objects from our sight. Faint deep sky objects become difficult or impossible to see through the murk of light pollution. Even bright nebulas like the Orion and Lagoon Nebulas lose much of their delicate detail. The Moon and planets are not affected; they require steady air more than dark skies, so they remain good targets for city-dwelling observers.

The International Dark-Sky Association is waging the fight against light pollution. The IDSA was founded in 1988 with the mission of educating the public about the adverse impact that light pollution has on the night sky and astronomy. Through educational and scien- tific means, the nonprofit IDA works to raise awareness about the problem and about measures that can be taken to solve it.

Do you need help dealing with local officials to con- trol street or building lighting in your area? The IDA’s extensive support materials can show you how. Help preserve dark skies, join the IDA today! For information, write to IDA, 3225 N. First Ave., Tucson, AZ 85719-2103 or visit their website: www.darksky.org.

The best way to avoid immediate problems with light pollution, however, is to take your telescope to where there are dark skies. You will be amazed at how many stars you can see when you get away from the city lights

Tracking Celestial Objects

The Earth is constantly rotating about its polar axis, com- pleting one full rotation every 24 hours; this is what defines a “day”. We do not feel the Earth rotating, but we see it at night from the apparent movement of stars from east to west.

When you observe any astronomical object, you are watch- ing a moving target. This means the telescope’s position must be continuously adjusted over time to keep an object in the field of view. This is easy to do with the StarBlast 6 because of its smooth motions on both axes. As the object moves off towards the edge of the field of view, just lightly nudge the telescope to re-center it.

Objects appear to move across the field of view faster at higher magnifications. This is because the field of view becomes narrower.

Eyepiece Selection

By using eyepieces of different focal lengths, it is possible to attain many magnifications or powers with the StarBlast

6.Your telescope comes with two Sirius Plössl eyepieces (Figure 9): a 25mm, which gives a magnification of 30x, and a 10mm, which gives a magnification of 75x. Other eyepiec- es can be used to achieve higher or lower powers. It is quite common for an observer to own many eyepieces to access a wide range of magnifications.

25mm eyepiece

10mm eyepiece

Figure 9. The 25mm and 10mm Sirius Plössl eyepieces.

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