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Q: Computerizing A Telescope ( Answered 5 out of 5 stars,   2 Comments )
Subject: Computerizing A Telescope
Category: Science > Astronomy
Asked by: misterrachel-ga
List Price: $5.00
Posted: 14 Jan 2003 08:50 PST
Expires: 13 Feb 2003 08:50 PST
Question ID: 142523
I own an Event Horizon 6" Newtonian Reflector telescope. It's
currently on an equatorial mount (the one that it came with). I know
that some telescope companies (Celestron, for example) have scopes
that come with computerized mounts that will automatically find any
star, planet, etc... and guide your telescope to it. I would like to
have the same kind of thing on my telescope, but I don't know if there
is a product that I can buy that will work with my telescope/mount.
(and I'm on a budget here).

Any insight?
Subject: Re: Computerizing A Telescope
Answered By: kutsavi-ga on 14 Jan 2003 15:47 PST
Rated:5 out of 5 stars
Hey there Misterrachel, 

I'm familiar with the type of mount that's on your telescope, and it
ocurred to me when I read your question that it wouldn't be possible
to computerize your mount.  In order to verify this, I called
Oceanside Photo and Telescope, a retailer near me with a national
reputation in the astronomy community.
I spoke with Ben, one of the sales people that I trust implicitly,
(Ben sold me my largest telescope, a 10" Dobsonian a few years ago),
and he verified my initial suspicion.  "No way to computerize it," was
his quote.

Conventionally, the type of mount that is computerized after purchase
is a Dobsonian.  The market is awash in instructions and products for
those, but not so for equatorial mounts.

So, short of computerizing, there are a couple of options:

First off, you *might* be able to motorize it.  If you are interested
in this option, there are motors available called clock motors.  They
are essentially simple motors that would drive the hands of a small
clock, hence the name.  They are adapted to fit on equatorial mounts. 
As the clock motor turns the telescope, the object you are watching
stays centered in the field of view of the telescope.  Really though,
the only advantages of motorizing an equatorial mount would be for
photography and for long viewing of an object once it was found. 
Simply motorizing a mount does not help locate objects for viewing.

If your equatorial mount is designed with setting circles, and most
are, there will likely be gear teeth under the lip of the Right
Ascension disk, which is the disk that lies parallel with and directly
beneath the body of the telescope.  If there are teeth there, you will
be able to attach a motor to the mount and use it to drive the
telescope.  If there are no gear teeth, I was unable to find a
motorizing option for you.  In that case however, you *should* be able
to use some sort of a friction device attached to a clock motor rather
than the cogged gear.  That's a backyard, shadytree solution, though,
and one that I've never performed nor seen any examples of.

After mentioning that you're on a budget, I would suggest that you buy
a clock drive for your scope only if the price of the drive is
sizeably less than the purchase price of your telescope.  The drives I
was able to find that appear to be compatible with a mount such as
yours run between @100.00 and $200.00 US:

Clock drive and an auto focuser for equatorial mounted telescopes:
($289.00 US)

Another clock drive from Tasco:
($267.63 US)

The least expensive drive I was able to find:
($119.95 US)

If the drives seem a little pricey, I would suggest buying a star
atlas and learning to use the setting circles already on the mount. 
This proceedure isn't all that difficult and will pay off in your
future observing by allowing you to find any object, anywhere in the
sky at any time.  Right Ascension and Declination are just like
latitude and longitude on Earth, except instead of looking down on a
sphere from above, you're looking *out* toward the surface of a
sphere, as though you were inside a globe and the lines of latitude
and longitude were intersecting above you.

By learning to use RA and Dec. you will also be preparing yourself for
the next big step in amateur astronomy:  buying a bigger telescope ;-)
 Then you'll be able to either buy a huge Dobsonian and manually slew
it to any object in the heavens almost without a second thought, or
sound the ultimate professional when describing the field of view in
your new Schmidt-Cassiegrain.  Nothing equals the satisfaction of
knowing your way around the skies when out observing, and nothing gets
you more familiar with them than using atlas and coordinates to find

Here are instructions from Meade on how to use the setting circles,
edited below for use on any equatorial mount:

"Understanding Celestial Movements and Coordinates

To line up [your telescope], follow this procedure: 

Release the Azimuth lock of the Azimuth base, so that the entire
telescope-with- mounting may be rotated in a horizontal direction.
Rotate the telescope until the polar axis (10) points due North. Use a
compass or locate Polaris, the North Star as an accurate reference for
due North.

Level the mount, if necessary, by adjusting the heights of the three
tripod legs.

Determine the latitude of your observing location by checking a road
map or atlas. Release the latitude lock (9) and tilt the telescope
mount with the latitude adjustment knob (11) so that the pointer
indicates the correct latitude of your viewing location on the
latitude scale (29).

Re-tighten the latitude lock (9).

If steps (1) - (3) above were performed with reasonable accuracy, your
telescope is now sufficiently well-aligned to the North Celestial Pole
for visual observations.

[Actually, rather than having to determine your latitude from a map,
it can suffice to find the North Star in the field of view of the
telescope and center it.  This will result in the telescope being
automatically positioned at the correct angle.]

Once the mount has been polar-aligned as described above, the latitude
angle need not be adjusted again unless you move to a different
geographical location (i.e. a different latitude). The only polar
alignment procedure that need be done each time you use the telescope
is to point the polar axis due North, as described in step (1) above.

Setting circles of the polar aligned equatorial mount can facilitate
the location of faint celestial objects not easily found by direct
visual observation. To use the setting circles, follow this procedure:

Use a star chart or star atlas, and look up the celestial coordinates,
Right Ascension and Declination (R.A. and Dec.), of an easy-to-find
bright star that is within the general vicinity of the faint object
you wish to locate.
Center the determined bright star in the telescope's field of view.
Manually turn the R.A. setting circle to read the R.A. of the object
now in the telescope's eyepiece.

The setting circles are now calibrated (the Dec. setting circle is
usually factory calibrated). To locate a nearby faint object using the
setting circles determine the faint object's celestial coordinates
from a star chart, and move the telescope in R.A. and Declination
until the setting circles read the R.A. and Dec. of the object you are
attempting to locate. If the above procedure has been carefully
performed, the faint object will now be in the field of a low power

The R.A. Setting Circle must be manually re-calibrated on the current
Right Ascension of a star every time the telescope is set up, and
reset to the centered object's R.A. coordinate before moving to a new
R.A. coordinate setting. The R.A. Setting Circle may two sets of
numbers, the inner set is for Southern hemisphere use while the outer
set of numbers (the set closest to the R.A. gear), is for use by
observers located North of the Earth's equator (e.g., in North

If you need an atlas, "Sky Atlas 2000.0, 2nd Ed." is the standard and
can't be beat.  The deluxe edition has fold-out pages and are
exquisite works of art, covering every portion of the sky in the
northern and southern hemispheres:

Sorry that your prefered solution isn't practicable, but I know that
you can have as much or even more fun using the alternative methods.

If you need clarification of any of this information I'm more than
happy to provide it.

Have fun and dark skies, 

Clarification of Answer by kutsavi-ga on 14 Jan 2003 16:13 PST

Immediately after I posted my answer I found a web page showing how
someone motorized a mount very similar to yours.  They fabricated
everything themselves, however, using quite a bit of engingeering
know-how and ingenuity:

Also, I neglected to append my search terms:

attaching drive equatorial mount

motorizing equatorial mount

motorizing orion equatorial drive

motorizing tasco equatorial drive

telescope clock drive

telescope clock drive equatorial mount
misterrachel-ga rated this answer:5 out of 5 stars and gave an additional tip of: $2.00
Thank you for your detailed response!

Subject: Re: Computerizing A Telescope
From: iang-ga on 15 Jan 2003 06:26 PST
Have a look at digital setting circles - they may provide at least
part of the answer for you.

Ian G.
Subject: Re: Computerizing A Telescope
From: kutsavi-ga on 16 Jan 2003 15:31 PST
Digital setting circles would be an option and I looked into them
during my research.  However, their cost, ($200-$400), and the amount
of know-how needed to install them seemed to make them impractical for
the type of telescope being considered.  There are many instructions
for designing and building your own digital circles, but I assume that
the user is a novice and not really ready to start designing and
constructing things like servo motors, digital display units and the

As I stated in my answer, I would seriously question the advisablity
of adding even a clock motor to the drive if the motor cost more than
a significant fraction of the original purchase price of the
telescope.  The digital setting circles that I looked at on the web
all required additional hardware to attach them to the mount, which
only adds to the price.

I still have to suggest using the existing vernier setting circles on
the telescope and then after mastering them, to go ahead and purchase
a bigger, nicer telescope with the GOTO/computerized hardware already
designed into the mount.  A bit purist of me maybe, but the payoffs in
enjoyment gained by learning the basics in the long run far exceed the
immediate gratification of the high-tech fix. ;-)


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