Polar Aligning the LX200Gps in the Southern Hemisphere

At the end of this process I was able to get my alignment to less than 1 arc minute (1/60th of a degree) of the SCP.

Initial Alignment

This method will put you to within a few degrees of the SCP. I consider this an approximate polar alignment which is suitable for visual use and short exposures with short focal lengths e.g. Piggyback SLR or DSLR work with exposures under 3 minutes. If greater accuracy is needed please proceed to the next sections.

Step 1 – Get Familiar with the Wedge

Learn how to mounting the telescope onto the wedge. Make sure you have someone help you for the first couple of times. I can lift my 10 inch onto the wedge all by myself. However I wouldn’t want to do it with a 12 or 14 inch.

Important: Learn how to use the wedge, when you turn the adjustment knobs make sure you note which direction the wedge moves as you will need this for later.

Step 2 – Setting the Wedge Latitude

  1. Find your observing latitude. A good resource for this in Australia is Geoscience Australia

  2. Mount the wedge on a level tripod and set the wedge latitude using the scale on the side of the wedge.

  3. Mount your telescope on the wedge.

  4. Without the telescope powered up manually slew the telescope so it points straight up towards the sky with the lens/dust cover on.

  5. Adjust the telescope in the DEC axis with the fine adjustment knob until the DEC is reading your latitude on its arm. E.g. -38 degrees.

  6. Place a sprit level on top of the dust cover and level your telescope using only the big knob at the back of the wedge. This process will set the latitude of the wedge to your approximate observing location. Incidentally the latitude adjustment on my wedge was 2.5 degrees out. If you want you can then loosen the hex nut on the wedge and correct any error you may have.

Step 3 – Setting the Wedge Azimuth

There are two ways of doing this: Compass Method & LX200Gps Method

Compass Method

  1. Find out the local magnetic variation. You can do this by calling the local aero club and speaking to a pilot. They should know what the local magnetic variation is as they need it to set the gyroscopic compass in the aircraft. Otherwise gets your hands on a copy of the ERSA from the local aero shop or order it off Air Services Australia it costs around $25. There are 500+ Australian aerodromes with the magnetic variation for each one. It will be good for a few years.

  2. Buy yourself a compass made for Australia and disregard the inbuilt wedge one. Compasses have to be made for a general area otherwise pointing errors will be introduced because of magnetic dip.

  3. Use the compass and align the needle north/south. This is magnetic north/south you will need to compensate for local magnetic variation to get true north/south. My local area magnetic variation is East 13 degrees which means true north is located 13 degree East of magnetic North or true South is 13 degrees West of magnetic South. Magnetic variation changes slowly over the years. Note the direction you are pointing and align the wedge to this.

LX200Gps Method

LX200Gps has a GPS in it which compensates for magnetic variation.

  1. Setup the LX200Gps without the wedge and do an automatic alignment as normal.

  2. Using the Autostar II controller holds down the “mode” button for 2-3 seconds and then scroll to you get the Alt/Azi readout.

  3. Using the buttons on the Autostar II controller move the telescope around until the telescope reads 180 degrees (true south).

  4. Mark out the north/south line using a string and pegs or make a mark on the ground.

  5. Attach the wedge to the mount using the string line as a guide.

Step 4 – Polar Alignment and Autostar II

  1. Make sure you have set the following in Autostar II.
    1. Turn on “Acquire GPS signal at Start-up”

    2. Make sure you tell Autostar II you are mounted in Polar mode.

  2. Reboot/Power up the LX200Gps.

  3. Set the telescope in Polar Home Position after it has gone through its Smart Drive Calibration (as this moves the RA drive a few degrees). The polar home position is when the RA drive to reads “00” and the DEC reads “-90”. This will point the telescope roughly at the South Celestial Pole.

  4. Select One Star Align.

  5. The telescope will slew around and try and centre Sigma Octantis which is a dim 5.4 mag star which makes it nice and fun to find!

  6. Every time I have followed this previous alignment procedures Sigma Octantis ends up well within the Meade Finder Scope (as long as you have aligned it to the telescope prior). Refer to the images below for the distinct pattens of stars which will help you find Sigma Octantis.

    Celestial South Pole - 1st January 2005 Celestial South Pole - 1st March 2005 Celestial South Pole - 1st June 2005 Celestial South Pole - 1st September 2005
  7. Use the adjustments on the wedge and centre Sigma Octantis in the Finder Scope first and then in the eyepiece. Bonus points for an illuminated reticle eyepiece. Then press “Enter” on Autostar II.

  8. Autostar II will then select another star. Centre the star using the up/down/left/right buttons on Autostar II and then press Enter.

  9. You’ve done it! You know if you’ve done it right as your slews should place targets somewhere within the 26 mm eyepiece assuming you have trained your drives correctly.

Step 2 of 4 – Drift Alignment

Skip to Navigation Menu