Alignment Stars

The 6 listed alignment stars are a recommendation of stars to use for aligning a GoTo telescope. It is compiled by reference to the list of Celestron Alignment Stars entered into ‘Starry Night Enthusiast then chosen according to an expanded criteria based on Celestron recommendations of how to choose your stars (see below)

The listing is two groups of three that can be used for the ‘Sky Align’ procedure below.  The first two stars in the list can be used for the ‘Two Star’ procedure, with the third used to add an additional star to create the simulated ‘Three Star’ procedure.

Where possible, the stars chosen are

  • at least 40º to 60º apart from each other
  • between 15 and 45 degrees altitude for easy alignment
  • first two in the set has one east and one west of the meridian
  • first two in the set are from the south, through east, to the north, thus ignoring west
  • third star is in the west, at between 20 and 40 degrees altitude, so it does not set for an hour or so.

So, what is the difference of the procedures?   Personal preference.

Which one do we recommend?   Again, personal choice.

Alignment Overview

Select alignment stars that are as far apart in the sky as possible. For best results,

  •             Ensure the third alignment star does not lie in a straight line between the first two stars
  •       Select stars at least 40º to 60º apart from each other.

For the best accuracy, center the alignment stars using the same final movements as the direction of the GoTo Approach (by default this will be the up and right arrow buttons). Approaching the star from this direction when looking through the eyepiece will eliminate much of the backlash between the gears and assure the most accurate alignment possible.

Below is a simplified listing of the Celestron Alignments for their GoTo computerised telescopes. For a more detailed procedure pertaining to your telescope, please refer to your Celestron user manual.

Sky Align

Preperation

SkyAlign must be used with the telescope mounted in alt-azimuth.
1.  Power on. The hand control display will say CPC Ready.
2. Press ENTER to choose SkyAlign. The hand control will display
     a. “Enter if OK”,
     b. “Undo to Edit”
     c. “GPS Linking”
3. Press ENTER to accept the time/site information.
4. The hand control will display a message reminding you to level the tripod if you already haven’t done so. Press ENTER to continue.

Procedure

1. Use the arrow buttons on the hand control to slew the telescope towards any bright celestial object in the sky.
      Including the Moon or Planets. Center the object in the crosshairs of the finderscope and press ENTER.
2. Center the bright alignment object in the eyepiece and press the ALIGN button.
3. For the second alignment object, choose a bright star or planet as far as possible from the first alignment object.
     Once again use the arrow button to center the object in the finderscope and press ENTER.
4. Then once centered in the eyepiece, press the ALIGN button.
5. Repeat the process for the third alignment star.

When the telescope has been aligned to the final stars, the display will read Match Confirmed.

Press • UNDO to display the names of the three bright objects you aligned to
             • ENTER to accept these three objects for alignment.

Two Star Alignment

With the two-star alignment method, the CPC requires the user to know the positions of two bright stars in order to accurately align the telescope with the sky and begin finding objects.

Preperation

Two star alignment must be used with the telescope mounted in alt-azimuth.  Refer to your user manual for the equatorial procedure.
1.  Power on. The hand control display will say CPC Ready.
2. Use the UP and DOWN scroll keys to select Two-Star Align.
3. Press ENTER to choose Auto Two-Star Align.
4. Press ENTER to accept the time/site information..

Procedure

1. The SELECT STAR 1 message will appear in the top row of the display.
       Use the UP and DOWN scroll keys to select the star you wish to use for the first alignment star.
2. Press ENTER.
3. CPC then asks you to center the alignment star you selected.
       Use the direction arrow buttons to slew the telescope to the alignment star,
       carefully center the star in the finderscope.
4. Press ENTER when centered.
5. Center the star in the eyepiece

In order to accurately center the alignment star in the eyepiece, you may wish to decrease the slew rate of the motors for fine centering. This is done by pressing the RATE key on the hand controller then selecting the number that corresponds to the speed you desire. (9 = fastest, 1 = slowest).

6. Press ALIGN
7. CPC will then ask you to center a second alignment star.
    a. Press ENTER to automatically slew the telescope to the displayed star.
    b. Press UNDO button to display the next most suitable star for alignment.
    c. Use the UP and DOWN scroll buttons to manually select any available star.
8. Press ENTER to automatically slew the telescope to the displayed star.
9. Center in the eyepiece and press ALIGN

It is best to choose alignment stars that are a good distance away from one another. Stars that are at least 40º to 60º apart from each other will give you a more accurate alignment.

Once the second star alignment is completed properly, the display will read Alignment Successful, and you should hear the tracking motors turn-on and begin to track.

Re-Alignment

CPC has a feature which allows you to replace either of the original alignment stars with a new star or celestial object.

1.  Select the desired star (or object) from the database and slew to it.
2. Carefully center the object in the eyepiece.
3. Once centered, press the UNDO button until you are at the main menu.
4. With CPC Ready displayed, press the ALIGN key on the hand control.
5. The display will then ask you which alignment star you want to replace.
6. Use the UP and DOWN scroll keys to select the alignment star to be replaced.
    If you have “unassigned” objects , it is always best to replace those with an actual object.
7. Press ALIGN to make the change

Three Star Alignment

Your Celestron User Manual may not include instructions for a Three-Star alignment; however, the following is a method that can be used to perform one using the instructions found in your user manual

1.  Complete a Two-Star Alignment, as describe above.
2. Insert the third star using the Re-Alignment procedure, also listed above.