Star Ware: The Amateur Astronomer's Guide to Choosing, Buying ...

A Few Tricks of the Trade 357
even need to be able to see—or, for that matter, even know—Polaris. Instead, a
compass is more than adequate for initial aiming.
Begin by turning on the power to the setting circles or onboard computer.
While both are likely to be battery powered, the latter can really draw quite a
bit of power, draining a set of batteries very quickly. If at all possible, plug the
GoTo control into an AC wall outlet or use an extension cord. Let the computer
initialize. GoTo telescopes usually prompt you to enter a variety of information,
such as the date, time, your location (which may be selected from the
unit’s built-in database), and possibly the telescope model. Manually driven
digital setting circles do not. Instead, they require that you initialize the telescope
by aiming it at two of the stars in the onboard database.
Once everything is initialized, both work pretty much in the same way.
Select a target from the object database. In the case of GoTo telescopes, press
go and the telescope does the rest. If you want the same effect with manual digital
circles, say go, then move the telescope by hand. Watch the indicator on
the hand control box until the location reads “00,” which means the target is,
in theory, centered in view. Some fine adjustment is inevitable, but if you set
everything up correctly, the accuracy should be quite good.
Now that the technique for using setting circles is familiar, here is why
they should not be used, especially by beginners who are unfamiliar with the
sky. To my way of thinking (and you are free to disagree), using setting circles
or a computer to help aim a telescope reduces the observer to little more than
a couch-potato sports spectator flipping television channels between football
games on a Sunday afternoon. Where is the challenge in that? Observational
astronomy is not meant to be a spectator’s sport; it is an activity that is best
appreciated by doing. There is something very satisfying in knowing the sky
well enough to be able to pick out an object such as a faint galaxy or an attractive
double star using just a telescope, a finder, and a star chart. Even if you get
your setting circles perfectly aligned and master their use, you will be missing
out on the thrill of the hunt. Stalking an elusive sky object is much like searching
for buried treasure: you never know what else you are going to uncover
along the way. As you set your attention toward one target, you might turn up
other objects that you have never seen before. Of course, there is also that
slight possibility of striking astronomical pay dirt by stumbling onto an undiscovered
comet. Imagine that thrill!
All right, so maybe I have been hard on setting circles, maybe even a bit
unjustifiably. Make no mistake; setting circles are very useful tools when used
for the right reasons. There is no question that they are required to aim the
large, cumbersome telescopes in professional observatories where viewing
time is at a premium. They also serve a very real purpose for advanced amateurs
who are involved in sophisticated research programs, such as searching
for supernovae in distant galaxies or estimating the brightness of variable
stars. Both of these activities involve rapid, repetitive checking of a specific list
of objects. Setting circles can also come in very handy when light pollution
makes star hopping difficult. However, they should never be used as a crutch.
Most amateur astronomers will do much better by looking up and learning
how to read the night sky rather than looking down at the setting circles.