Drift Alignment in the Southern Hemisphere

This will provide a much closer polar alignment (within 5-20 arc minutes of the refracted SCP) which will be suitable for most astrophotography work for exposures under 5 minutes in length for most piggyback refractors and prime work on the LX200Gps. If you want to totally minimize field rotation I suggest you use the CCD method of drift alignment as it’s far more accurate in detecting arc-seconds of drift over the passing minutes.

You can always improve the polar alignment by having the star not drift for more than 10, 20 or 30 minutes. 30 minutes should bring you within 2-5 arc minutes of the SCP.

Attempting drift alignment without an illuminated reticle eyepiece is near impossible in my opinion.

What do we mean by drifting? It’s when the centred star between the crosshairs begins to drift up or down in the DEC axis. The drift is cause by inaccurate polar alignment.

  1. The first thing you need to do in centre the star in the cross hair of the eyepiece. Then selecting a slow slew speed press the up and down arrows of the Autostar II controller. This will cause the star to move up and down or side to side in the eyepiece. Align the cross hairs with this movement. You will know when you have it right when you can centre the star and it moves along the extended crosshair line in both DEC (up/down) and RA (left/right).

  2. The drift happens in the DEC axis (up/down on the Autostar II controller) so if you are unsure of which crosshair line is the DEC axis press the up/down arrows and look at which crosshair line the star follows. Ignore any drift in the RA axis (left/right) this is caused by an incorrect tracking setting or periodic error.

  3. You will also need to determine which way the star was drifting. This can be done by centring the star in the cross hair and then pressing the up/down button to move the star off centre along the extended cross hair in the DEC axis.

    What we are doing here is simulating “drift” that may accrue over a period of time. Note where the star is in the eyepiece press the Autostar II to bring it back to centre, while doing this look at which way the telescope is physically moving, it will be either heading north or south in the DEC axis and this is the way of the “drift”. This is what telescope nutters mean by the star drifting north or south.

  4. Drift needs to be corrected in both wedge axis’s up/down (Latitude) which makes the telescope point higher or lower then the SCP and left/right East/West of the SCP. This is done by pointing the telescope to a particular area of the sky and watching a star drift in the eyepiece. To correct the wedge for being set to high or low (up/down) in its latitude select a star about 20-25 degrees in the east near the celestial equator. Centre the star in the eyepiece then walk way for about 3-7 minutes.

    Star Chart - Showing you how to select your target star
  5. After 3-7 minutes take a look in the eyepiece did you notice any drift? If so you will have to make a correction to the big knob on the back of the wedge. Remember the very first step? You should know which way to turn the knob to make the wedge point higher or lower.

  6. Correcting For Drift in Wedge Latitude. If the star:

    1. Drifted North = Your Wedge is to Low, Raise It

    2. Drifted South = Your Wedge is to High, Lower It

    Turn the knob very carefully, small adjustments go along way. There isn’t too much backlash in this adjustment knob. Make the adjustment then repeat step 6 until no drift happens over 5 minutes.

  7. After you have corrected the latitude adjustment its time to move onto the East/West wedge adjustment. To correct the wedge for being set too Far East or West. Select a star where the meridian and celestial equator meet. Centre the star in the eyepiece then walk away for about 3-7 minutes.

    Star Chart - Showing you how to select your target star Star Chart - Showing you how to select your target star
  8. After 3-7 minutes take a look in the eyepiece did you notice any drift? If so you will have to make a correction to the two knobs located on the sides of the wedge. Remember the very first step? You should know which way to turn the knob to make the wedge point to the east or the west.

  9. Correcting For Drift in Wedge in the Azimuth. If the star:

    1. Drifted North = Your Wedge is too far East, Rotate it West (Right)

    2. Drifted South = Your Wedge is too far West, Rotate it East (Left)

    Turn the knob very carefully, small adjustments go along way. In the Meade SuperWedge there is a super excessive amount of backlash. You may have to turn the knob 5-6 times before the knob begins to move the wedge. Make the adjustment then repeat step 6 until no drift happens over 5 minutes.

  10. The longer the star stays put the better your polar alignment is. I prefer the CCD method of drift alignment as this method shows you how the corrections are bring you closer to SCP. Additionally with the CCD method it is possible to get inside 1 arc-minute of the SCP. This might seem a bit extreme however if you want to image with your LX200Gps at F10 or F6.3 and want to stop field rotation this is what is needed to be done to take good photos in my opinion.

Step 3 of 4 – Precise CCD Drift Alignment

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