Astrophotography 101 - Polar Aligning A GoTo EQ Mount

Every Imaging session starts off with setup, you’ll need to get everything put together, connected and verify all your equipment is functioning properly before you take any images.

Polar Alignment

An accurate polar alignment is vital to getting the longest possible exposure times and therefore the best signal to noise ratio. Polar alignment is the process of aligning your mount with the North Celestial Pole using Polaris, The North Star (This method of polar alignment only applies to those who can see Polaris from their location).

To do this you will use the polar scope built into your mount and you’ll also need an app to see where Polaris should be within that view since the star itself is slightly off from the true NCP, I like to use Polaris View which can be found on Google Play.

Things to know:

· Altitude: The height of a celestial object above the horizon, measured as an angle.

· Azimuth: The horizontal angle or direction.

· What direction North is relative to you

· Your Latitude

Step 1: Start by leveling your tripod before putting your mount on, a level tripod will make it easier to find Polaris. Be sure to orient your tripod so the mount will be facing as close to north as possible.

Step 2: Find the altitude adjustment on your mount, the altitude of Polaris will be equal to

your latitude, so you will need to set the altitude adjustment to your exact latitude, for me that’s 39 degrees north.

Step 3: Once it’s dark and you can see Polaris in the sky (it’s fairly bright, at the end of the little dipper’s handle) take a look through your polar scope, once you’ve found Polaris you’ll need to adjust your azimuth control knobs and possibly your altitude until you’ve matched up your view with what Polaris View shows.

Actual view through polar scope

Star Alignment

After you’ve polar aligned you will likely need to align your mount to correct for any error in its alignment through your hand controller or software. Refer to your mount’s manual for directions specific to your mount.

Start by choosing a bright star to align with that’s visible from your location (referring to a planetarium app is helpful). Find that star in your hand controller's database and slew the mount to where it thinks it is, then simply find the star and center it in the view of your lens or telescope (having a properly aligned finder scope will help) and finish your alignment procedure.

Plate Solving

Plate Solving is built into some imaging software suites such as NINA and APT and can allow you to skip the star alignment procedure entirely. It works by taking an image from your camera and comparing it to a database of star positions to determine where your setup is pointed, it can then re-slew your mount to your target based on that information.