What a gorgeous moonrise today. I thought of hiking up to get a better vantage point to capture tonights moonrise. A host of conflicts would prevent that. As it turned out, it really didn’t matter. Moonrise was followed by a spectacular positioning of the (almost) full moon and the Belt of Venus. The Belt of Venus is the point in the accompanying photo where the sky changes color from blue to purple. This is Earth’s shadow being cast onto the upper atmosphere. In this photo, the Moon is sitting just above the belt.

Proper polar alignment is one of the most critical issues for deep sky astrophotographers. If your mount is not spot-on as far as alignment goes, you’re going to have a heck of a time taking the long exposures needed to snag the elusive faint fuzzies that inhabit the night sky. Sure, you can take a number of short exposures and stack them. This will only get you so far though. At some point, your signal to noise ration simply isn’t high enough to reveal the details that will allow you to separate yourself from the masses. Depending on the focal length of your telescope, a poor polar alignment might limit you to exposures in the 15-30 second range, perhaps less. Beyond this, stars will elongate and quickly begin to look like footballs, or worse, lines… not the round points of light that they should be. As your stars begin to elongate, the faintest details in your exposure will simply disappear, the faint light they emit being spread so thinly that it gets lost in the background of your image. You’ve now removed any hope of creating the spectacular image that everybody is talking about.

Polar alignment, balance, mount stability and tracking smoothness will either work for you harmoniously or work against you at every opportunity. There are things you can (and will have to) do as you progress as an astrophotographer to improve each aspect of your imaging. At some point, you’ll fix one glaring issue only to reveal the next, more subtle, layer of issues. Don’t take this as a bad thing. This is a desirable progression. Eliminating the worst defects and working to remove the lesser defects, until all that remains is a spectacular image. One that you can be proud of, and one that will make other astro-imagers jealous.

The next couple of posts will focus on what it takes to get a good polar alignment. The first will simply describe the polar alignment process in detail and walk you though it. Master this, and you’ve got alignment licked. The second, will describe how some available tools can be used to improve your alignment. Specifically, we’ll look at the Gemini GoTo System and its Polar Alignment features. Other mounts may have similar features that you can use.