The Field Document is a supplement to the LX200 Polar Alignment Procedure. Please refer to the main document for further information on any aspect of the following. The Field Document is intended for use beside the telescope and may be printed double sided on a single sheet of paper and laminated as necessary.
1) Initial Alignment
Skip this step if the tripod is already in good alignment. Perform this step if the telescope has been moved by 1/2 degree or more geographically from a previous location.
Orient the tripod as accurately as possible in a N/S direction by magnetic compass or by 'gunsighting' it on Polaris or a landscape object that is in a known N/S direction. Then level the tripod.
For more information see the Procedure for New Users.
2) Power Up / Sync
This step must always be performed.
a) Mount the LX200 on the wedge. If appropriate, try performing the Pre-Alignment (see the Procedure for New Users). Make sure the RA and Dec locks are tight and power up. Do not enter the LX200 Polar Alignment procedure and do not adjust the RA and Dec setting circles.
b) Slew to a star in the southern part of the sky, centre it in a guiding eyepiece, select that star in the LX200 database, then Sync on it (Note: you may find it easier if you select a bright star that can be accessed by name from the Name database).
3) Intermediate Alignment
Skip this step if the wedge is already in good alignment. Perform this step if the telescope has been moved by 1/2 degree or more geographically from a previous location.
a) Select Star 19 from the Star Database (or Polaris from the Name database) and slew to it (press Goto).
b) Use wedge adjustments to centre Polaris in the finderscope (or Telrad). This should bring Polaris into the FOV of the scope guiding eyepiece.
c) Make further wedge adjustments until Polaris is roughly centred in the guiding eyepiece (this is not a critical adjustment).
If you run out of azimuth adjustment range during the above wedge adjustments, then the tripod will need shifting. First, centre the azimuth adjustment within its range, then shift the tripod by small increments until Polaris is within the finderscope. After shifting the tripod, re-level it. Then proceed with the wedge alignment as above until Polaris is centred in the guiding eyepiece.
4) Refined Alignment
This step must always be performed.
Proceed with Chuck Vaughn's Drift Method of Polar Alignment. Note that step 1 has already been performed in the above.
Drift Method of Polar Alignment
1. Set up your scope as normal. Use one of the many methods to roughly align using Polaris. This can be as rough as just getting Polaris in the center of your sighter scope. The closer you get here, the shorter time you will spend drifting. (Hint: Level your tripod - it makes life easier)
2. Put a diagonal and illuminated guiding eyepiece in your scope. About 200 power is the minimum needed for adequate sensitivity during drifting. Rotate the eyepiece so that a star moves parallel to the crosshairs in Dec and RA when using the slow motion controls. Align it so that Dec is up and down (North & South) and RA is right and left (East & West).
3. Find a star very near the meridian and about +20 degrees declination and align it to the center of the guiding eyepiece. Let your scope track (you may guide in RA only if you wish) and watch for Dec drift (up or down). Unless your alignment is very close, you will see drift in 5 to 30 seconds.
4. If the star drifts up, turn the azimuth knob that makes the star move right in the field. If the star drifts down, turn the azimuth knob that makes the star move left in the field (These adjustments are reversed for a Newtonian). After adjustment, use the slow motion controls to re-center the star. Repeat this until there is no drift for at least 5 minutes. Note: If you see drift in less than 5 seconds at 200X, you are probably 10 or more eyepiece fields off in azimuth. Give the knob a good crank. This may have to be repeated 3 or 4 times to notice the drift slowing. If you don't see any drift for 30 seconds or so, you may only be 1 or 2 eyepiece fields off. Make your azimuth adjustment accordingly. If after adjustment the star drifts in the opposite direction, you went too far.
5. Find a star on the equator and within 15 degrees of either the Eastern or Western horizon. Repeat (2) and use the guidelines from (3) and (4). For Eastern horizon: if the star drifts up, adjust the elevation to move the star down. If the star drifts down, adjust the elevation to move the star up. For Western horizon: if the star drifts up, adjust the elevation to move the star up. If the star drifts down, adjust the elevation to move the star down. Repeat until there is no drift for at least 5 minutes.
6. If you made a large correction in elevation (several degrees or more), go back and check the azimuth, otherwise you are done. With a little practice, it ought to be possible to complete the procedure before the end of twilight. Try it in your back yard until you are confident. I have found this method to be accurate enough for astrophotographs of up to 3 hours for small fields (less than 1 degree) and up to 2 hours for larger fields (up to 5 degrees) for declinations between +70 and -70 degrees. For exposures longer than these and closer to the poles, a photographic method of polar alignment that is applicable only to permanent installations may be required.
7. It must be emphasized that the star cannot drift at all for 5 minutes to achieve the exposure times stated above. If you judge the drift by bisecting a star with a line in an illuminated eyepiece the star must stay bisected for the full 5 minutes. Experience has shown that if the star has drifted as little as half it's diameter then field rotation will begin to creep into long exposures.
All text comprising the Drift Method of Polar Alignment is the Copyright
of Chuck Vaughn
Except where otherwise noted all text comprising the LX200 Polar Alignment Procedure is the Copyright of Philip Perkins