In order to do long-exposure astroimaging, an equatorially aligned telescope is necessary to allow your telescope to properly track the motion of the sky. Precise tracking still depends on an accurate polar alignment. Even with a visible star very near the North Celestial Pole (NCP), the true celestial pole can be a very elusive place to find without assistance.
That’s where All-Star™ Polar Alignment comes in. All-Star is our exclusive, innovative polar alignment procedure—available on select Celestron computerized telescopes—that allows users to choose any bright star (not just one near the NCP) while the software calculates and assists with polar alignment.
Here's how it works.
Once your telescope is aligned with two or more bright stars, All-Star allows you to choose any bright star listed in the NexStar hand control. This star will assist the software in correctly aligning your telescope’s mount with the North Celestial Pole.
Using the telescope's Sync function, the mount will point to and center a bright star with a high degree of accuracy. Once centered, the mount will point the telescope to the exact position that the star should be if the mount was precisely polar-aligned. When you adjust the mount’s altitude and azimuth controls to re-center the star in the eyepiece, you are actually moving the mount’s polar axis to the exact position of the North Celestial Pole.
Can I use Polaris to polar align my telescope?
Since Polaris is very close to the NCP and not very bright, we do not recommend it for the All-Star method. The advantages of being able to use stars other than Polaris are twofold:
- Polaris is not always visible. So not only can you use a variety of other stars, but ones that are brighter and more prominent than Polaris.
- The star you choose will be farther away from the NCP, allowing for greater accuracy when centering the star in your eyepiece.
Which stars are best to use for polar aligning?
For best results, choose a bright alignment star that is near the Meridian, preferably close to the celestial equator. Try to avoid stars that are close to the west/east horizon or directly overhead; they can be more difficult to center using the mount’s altitude and azimuth controls. Also, stars too near the celestial pole are less accurate than those further away.
Will I lose my alignment after I polar align?
No. The mount will retain its alignment, but some amount of accuracy may be compromised depending on how much the mount was moved during polar alignment. Although the telescope’s tracking may be very good, pointing accuracy may need to be improved, especially if you are trying to locate small objects on a CCD chip.
How do I polar align my telescope using All-Star Polar Alignment?
- Align the telescope with the sky using the Two-Star Alignment method.
- Align to at least one calibration star on the opposite side of the meridian.
- Select a suitable bright star from the NexStar hand control’s database. Slew the telescope to the star.
- Press the Align button. Select “Polar Align” then “Align Mount” from the list.
- The telescope will then re-slew to the alignment star and ask you to center it in the eyepiece in order to "sync" on the star.
- The telescope will slew to the position that the star should be if it were accurately polar-aligned.
- Use the mount’s altitude and azimuth adjustments to center the star in the eyepiece.
- Press the Align button.
- If necessary, update the telescope’s star alignment.