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Roland's polar alignment method


Derek Wong <dawong@...>
 

A repost of Roland's polar alignment method (with his permission):

...actually, I use another method to achieve accurate results, a
modification of method 3 in the manual. I choose a star that is close to
the meridian overhead, and center the crosshairs on it. Then I change
the clock time by 1 hour and enter the same star on the hand control.
The telescope now slews to the other side of the mounting, and the star
will be offset in declination by some amount (the star can also be off
the crosshair in R.A. but this is not due to polar alignment, rather it
is due to non-orthogonality of the telescope vs. the mounting). To polar
align, the star is moved half way to the center of the crosshair by
turning only the altitude adjuster. The star is now brought the rest of
the way with the buttons, and a recal is done by pushing button #9. That
in effect sets the altitude of the mounting. If done properly, you don't
need to do it any more times, but you could do it again by resetting the
clock time to the original hour and slewing to the same star again on
the other side of the mounting. A final fine adjustment can be done the
second time. You can also adjust the orthogonality of your mounting by
shimming up one of the mounting rings until the star comes in in R.A
also.

The azimuth setting on the mount is done by picking a star in the north,
and then slewing to a star in the south at similar right ascensions.
Bring the star half way to the crosshair with the azimuth adjuster, and
the rest of the way with the buttons. Then hit #9 button to recal the
position. This way, the two adjustment axes are done totally
independently. It is highly accurate and very fast. I can do it in less
than 5 minutes and be dead on all night long.

Sincerely
Roland Christen

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Stephen E. Russell <sjruss55@...>
 

A repost of Roland's polar alignment method (with his permission):

The azimuth setting on the mount is done by picking a star in the
north,
and then slewing to a star in the south at similar right ascensions.
Bring the star half way to the crosshair with the azimuth adjuster,
and
the rest of the way with the buttons. Then hit #9 button to recal the
position. This way, the two adjustment axes are done totally
independently.

Sincerely
Roland Christen
Hello Group

A while back Derek posted this modified polar align method from Roland.
I have a 600 gto and 130f6. I've been using the polar one star method
which is fine for visual use. I decided to try using the other methods
to get more accurately aligned for some astrophotgraphy. I tried
unguided and with first method and anything over 2 minutes showed too
much trailing.
So time to get better aligned.

Using Roland's modified third method to adjust the azimuth, when
choosing the star in the North and then South star, what is meant by
similar RA? Since stars in North and South have a great difference in
RA, what stars should I be using here? In the third method it states to
choose two stars in the East or West with similar RA, this I understand.

As far as orthogonality is concerned, I used that method to see how far
I'm off. AP suggests to shim up one of the mounting rings. I'm using
the dovetail setup. I'm wondering if I might be wasting my time here
since I'm using the dovetail setup. Has anyone shimed up their rings
using the dovetail setup with any success? I figure that you need to
use the flat plate with the rings to keep the alignment. What do you
folks think about this?

Someone mentioned to use two hex wrenches to tighten down the azumith
bolts at the same time so you are not fighting with yourself when you
tighten one side at a time. They also mentioned using nylon washers
under the bolts. Should the nylon washer be used in replace of the
steel washer, or in conjunction with it, either above or below the
steel washer? I'm thinking on top of the steel washer might be best.

Thanks for any input here,
Stephen


Jeffrey D. Gortatowsky <mrrockets@...>
 

I don't have my AP 400GTo yet. So I'd really be interested in learn just what
you are referring to. No doubt it would be difficult until I actually use my own
GTO to polar align.

However:

when choosing the star in the North and then South star, what is meant by
similar RA? Since stars in North and South have a great difference in
RA, what stars should I be using here?
probably refers to the local meridian (for example). Lets say for the sake of
argument it is the end of June. Kochab, beta URSA Minor is near the meridian. I
am looking north and see Kochab which is at 14h 50m RA. I turn around and am now
looking south. Also near the meridian is Zubenelgenubi, Alpha Librae. It's RA is
also 14h 50m. Might that not be what Roland was refering to. Again I have never
used a GTO (this May I hope!!) so I could be full of star dust...

Clear Skies,
Jeff


Stephen E. Russell <sjruss55@...>
 

Jeffrey
I see the (star)light now. I was looking for a star in the north around the
side or below Polaris and of course ended up with a much different RA. Your
explanation was perfectly clear. I made it too difficult as usual. Can't
wait to try this method out.
If you go back to the #10 message posted you can see the rest of Rolands
explanation of his quick polar alignment method which is a modified version
of method three in the manual.
Thanks, Stephen

-----Original Message-----
From: Jeffrey D. Gortatowsky <mrrockets@home.com>
To: ap-gto@eGroups.com <ap-gto@eGroups.com>
Date: Tuesday, February 22, 2000 10:56 PM
Subject: [ap-gto] Re: Roland's polar alignment method


I don't have my AP 400GTo yet. So I'd really be interested in learn just
what
you are referring to. No doubt it would be difficult until I actually use
my own
GTO to polar align.

However:

when choosing the star in the North and then South star, what is meant by
similar RA? Since stars in North and South have a great difference in
RA, what stars should I be using here?
probably refers to the local meridian (for example). Lets say for the sake
of
argument it is the end of June. Kochab, beta URSA Minor is near the
meridian. I
am looking north and see Kochab which is at 14h 50m RA. I turn around and
am now
looking south. Also near the meridian is Zubenelgenubi, Alpha Librae. It's
RA is
also 14h 50m. Might that not be what Roland was refering to. Again I have
never
used a GTO (this May I hope!!) so I could be full of star dust...

Clear Skies,
Jeff

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