AstorPearls - Astronomy Software
 Polar Alignment Part 2

Warning

For those who live in the southern earth hemisphere: You can’t see Polaris - an unfortunate fact! But this doesn’t mean you can’t align your mount. You still can but not using this technique!

Using Polaris

Now, Equatorial mounts have an opening in the RA block that allows you to look through it and see Polaris this will tell you that you are very close to the NCP. Consult the manual of your mount for details on this, but generally you position the DEC block of your mount horizontally to clear the path through the RA axis so you can look through the opening and see Polaris. Now you know you are very close to the NCP!

What do you mean by very close?

Well, Polaris is not at the exact NCP it is very close to it and again, this brings us to yet another level of accuracy: using Polar Alignment Scope!

What are these polar alignment scopes?

It is very similar to your finder scope but it goes inside the Right Ascension block opening. Instead of a reticle with crosshairs, it has a reticle with constellations (big dipper, little dipper, and Cassiopeia). Alignment can be acheived by moving your mount such that Polaris overlaps with the mark on the reticle. Some Polar Alignment Scopes comes with two stars so you can get even better alignment. To use it, follow steps mentioned in Parts 1 of this article to get initial alignment then improve as follows:

  • Make sure location constellations on the finder coincide with the actual location of the constellation on the sky - if Polaris is exactly on the NCP we won’t care about this as rotating them won’t make difference but it is not so you have to do this.
  • Adjust right/left up/down fine tuning knobs of your EQ mount until Polaris falls on the mark.
  • If your polar alignment scope contains another star, try to adjust such that it also hit the mark. This will result in better alignment.
    Now you have a very good aligned mount!

Does this mean I’m ready for long exposure photography?

Not yet! To your surprise, this is good for less than a minute exposure. For longer exposure you need an almost perfect alignment - drift alignment will take you to our last level. See part 3 for details on how to do this.