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Re: Suggestions for new astronomy course



The telescope to buy for an astronomy course depends upon what you want
to teach or show. Here are two possible uses for a telescope in an
astronomy class:

(1) Teaching how to find things in the sky... how the objects move from
our point of view... how to set up and aim a telescope.

(2) Observing actual objects such as star clusters, galaxies, planets,
etc.

The first telescope we bought was a10-inch Dobson. We were after good
optics at a low price. It was a mistake. We never use it any more.
First, it's hard to find anything. Second, with no clock drive, you
have to keep readjusting it manually. Try taking a dozen students out
on a cold January night. Spend 15 minutes (or more) finding the object
you want. All this time the students are standing around bored and
cold. Once you've found the object, between each student you have to
reposition the scope. By the time every one of a dozen students has
seen the object, 30 minutes have gone by. If you're outdoors for 90
minutes you can see about three objects. And you'll have a bunch of
cold tired students who don't like astronomy.

Next we bought a couple 3" refractors with equatorial mounts and clock
drives. These are much better at teaching motions of celestial objects
because the mount is designed to follow objects by rotation around one
axis. If the setting circles are reasonably good, and you know how to
use them, you can find objects faster. Even if you never get very good
at it, it's still a good exercise to teach the students about celestial
coordinates and how to use setting circles. Therefore we still use
these refractors for that purpose. During the early portion of the
course when we teach celestial motions and we teach about using a
telescope, we have students do a polar alignment then have them find
something. Once we have found something, the clock drive keeps it
there. That means everyone can have a look without having to
re-position it. That's a great asset.

Therefore, for goal (1) above, we never use the Dobson any more, and we
use a couple 3" refractors on equatorial mounts. Students work in a
team of 3-4 to align the scope and find something. Small reflectors on
equatorial mounts and clock drives would also be good.

For goal number (2), we finally bought an 8" Meade LX200
Schmidt-Cassegrain. This telescope is computer guided once you align
it to two alignment stars. It is amazing. I would never teach
astronomy again without it. A class of 10-20 students can see more
things in one hour with one telescope than we could observe all week
with several other scopes. After it is aligned, you just punch in the
Messier number (or NGC number) of an object on the control pad, and the
telescope goes there... perfectly. And the drive mechanism keeps it
there. Since I don't have to do anything, I can talk to the students.
Here's what I do. After aligning the scope, I can say..."Tonight we
are going to look at a few star clusters. The first cluster is a
famous globular cluster...etc." While the students are taking turns
looking at it, I can keep talking and also answer questions. Students
will look for about 30 seconds each. As the line is dwindling, I begin
talking about the next object we will see and how it differs from what
we've seen already. Once the last person has looked at the current
object I punch in the code for the new object. Within 15 seconds the
new object is in view and we're starting a new of students to look at
it. With 12 students I can have them each look for 30 seconds at a
deep-sky object, and I can have them look at about 10 of these objects
in one-hours time. Incredible.

I take about 30 minutes to get to the site, set up the scope, and align
it. Students are welcome to join me for that if they're interested.
But they can also come at the prescribed time that I tell the scope
will be ready to go. If I have more than 12 students, I prefer to have
them come in groups... one hour per group. I organize viewing around
themes. Clusters. Galaxies. Colored Stars. Etc.

There are two telescopes that are excellent for this. The 8" Meade
LX200 and the 8" Celestron Ultima 2000. Each is about $2900 delivered.
Yes that's a lot of money. But it's worth it. For high-school use,
see if your local Lions Club or Rotary Club or whatever can help you
purchase it. It is difficult to decide which is the better scope.
Both have been reviewed in Sky and Telescope. The Meade is a bit more
substantial and heavier. But the heaviness makes it more difficult to
transport and set up, and it requires AC power or a hook-up to your car
battery. The Celestron operates from normal alkaline batteries and
transports easier. A hard choice. We wanted to do some
astrophotography and decided the heavier Meade might be better for
that. But every time I lug it around, I wonder.

I know there are people who swear by Dobsons. For teaching an
astronomy course populated by students who are more interested in
seeing something than fooling around with equipment and getting cold
and tired, I wouldn't touch a Dobson with a ten-foot pole. One
computerized scope is what I would buy first... and maybe last (if goal
(1) is not one of your goals). Find the money to do it.


Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817