Observing galaxies is not as easy as observing open clusters, globular clusters, or double stars. It takes both patience and skill. Even then, do not expect to see in the eyepiece anything remotely like the long-exposure photographs shown in astronomy magazines. Yet, if you have a good sky chart and have accomplished the art of starhopping, you are ready to learn to locate fainter galaxies.

VISUAL MAGNITUDE

The first problem you must overcome is being fooled by the posted visual magnitudes of the galaxies. Visual magnitude is based on the total light emitted from any particular object. We are accustomed to judging magnitude from stars, tight open clusters, and compact globular clusters. Galaxies observable in most amateur telescopes tend to be much larger in apparent size than these other more compact objects.

Since the light is spread out over a larger area, galaxies appear fainter. It has been my experience that galaxies appear between 1 and 2 magnitudes dimmer than most open and globular clusters of the same stated magnitude. I will explain several techniques for compensating for this problem. But first I will list the different types of galaxies.

BASIC TYPES OF GALAXIES

The most common galaxies we see are spiral galaxies like our own. They are made of spiraling arms of stars and dust coming from a central core. How one sees them depends on the tilt of their galactic plane as seen by us.

Assume our "plane" is the ground, and we are looking at a spiral galaxy straight overhead. If its galactic plane is parallel to us, the galaxy is considered face-on. These are the most difficult to see because their total light is spread out. Their opposites are called edge-on because their galactic planes are perpendicular to us. They appear as a narrow line with a center bulge. They appear somewhat brighter because their total light covers a smaller area. However, a lane of dust, which can be seen in some of them, blocks some of that light. Finally, many galaxies have galactic planes that are inclined to us somewhere between 0° and 90°. They tend to be the brightest of the spirals.

The second type of galaxy is called elliptical. They are usually circular, or ovals that are near circular in shape. They tend to be the brightest of galaxies but with almost no observable details. Ellipticals remind me of very faint globular clusters — round with no resolvable stars.

Finally, odd-shaped galaxies are called irregulars. Each has its own unique shape.

Since face-on galaxies appear the faintest and therefore the most difficult to observe, I will tell you my pointers to assist you in viewing them. You can then use the same techniques when necessary to view the other types.

OBSERVING TECHNIQUES

Follow the general rule for locating deep sky objects: start with the lowest power eyepiece you have. I use a 40 mm eyepiece, which is 25x in my scope. More light is concentrated in a smaller area, usually making the galaxy easier to see.

But if you can’t locate a rather faint object with low power, don’t give up. Try a little higher power. I have been able to see some fainter galaxies with my 27 mm, 35x eyepiece when I could see nothing with the 40 mm.

Another technique that is very helpful in seeing faint galaxies is learning how to use averted vision. It does work. Instead of looking directly out of

the center of your eye, look through the side of your eye. More light is allowed in through the side of your eye. Looking through the upper portion of your eye is supposed to work best.

Continue to stare at the exact position the galaxy is supposed to be in, according to your star charts. Sometimes it helps to gently tap on the side of your telescope. Occasionally this tapping will cause the faint object to suddenly "pop" into view.

If you do suddenly think you can see a faint galaxy with one of these techniques, be careful. Assuming that you do not have a clock drive, make sure that this sudden find moves with the stars and does not stay in the center of your eyepiece. If it doesn’t move, then your discovery has been one of wishful thinking rather than actual seeing. Don’t be embarrassed; it’s happened to me many times. But I have also have seen many fainter galaxies that did move when they were supposed to by using these techniques.

On smaller, dimmer galaxies, increasing to higher power will help to confirm a find. Otherwise, high power is reserved for those bigger and brighter galaxies that will allow for the observation of some detail.

TESTING YOUR SKILLS

To test your skills in locating galaxies, you might want to start on the list below. It contains examples of the different types of galaxies observable in most amateur telescopes.

M31, the Great Andromeda Galaxy, is observable with the naked eye, but viewed best with binoculars. Perfect seeing and a large telescope are necessary to see much detail in this tilted spiral. However, good seeing and a modest telescope are all that are needed to see its smaller and fainter companions, M32 and M110.

The Pinwheel Galaxy, M33 in Triangulum, is a large face-on spiral that is easy to locate with binoculars but can be downright elusive with a telescope. Even then, you can see very little detail because the light is spread out over such a large area. The best face-on spiral to view is M51 in Canes Venatici. Under dark skies and moderate power, you can begin to see its spiral arms. Its outermost arm stretches to it smaller and fainter companion, NGC5195.

M81 in Ursa Major is another bright spiral galaxy that is slanted toward us. If you look at it with low power, you can see its companion M82 in the same field of view. M82 is probably the most viewed irregular galaxy. By kicking up the power, you should notice a mottled or blotchy effect to this rectangular-shaped object.

M104, the Sombrero Galaxy, in Virgo and NGC4565 in Coma Berenices are the best looking edge-on galaxies. They are both easy to locate with low power. However, they can be seen in their best glory with high power. It allows you to see their galactic bulges and central dust lanes under good seeing conditions.

One of the brightest elliptical galaxies is M87 in Virgo. Because it is relatively bright, you might be able to locate it among the many galaxies in Virgo. However, if you cannot, be patient. Navigating the Virgo Cluster will be the topic of a future article in the Primer for the Advanced series.

NEXT ISSUE:LESSON FIVE: OBSERVING PLANETARY NEBULAE