Q: How Do I Use My New Telescope? Pt 2-Star Charts

Friday, May 25 2007 @ 01:00 pm EDT

Contributed by: bobmoody

Its about time, isn’t it? I mean getting around to this follow-up article for learning how to use your now not-so-new telescope. If you’ve followed my suggestions in Q: How Do I Use My New Telescope? Pt 1-The Finder Scope, then you’ve likely also pointed your scope at several other objects, maybe even at some of the brighter lights in the night or early evening sky. Some of those brighter objects might have been planets, and in this respect, if you didn't use any charts you can claim that you've actually made your very own independent discoveries of Saturn, or mighty Jupiter, or maybe even Venus.

Star Charts! Everybody needs them and uses one based on what your individual tastes are for how they look and how easy they are for YOU to use. Astronomy and Sky & Telescope magazines give monthly charts, but are these the best for you?
But the vast number of objects that you’ll want to see in your telescope are exceedingly dim. One of the best ways to find these objects is to use a star chart, and perform what’s called “the Star-Hop method” of locating deep-sky quarry.

I did the same thing and independently discovered Saturn on a cold, clear winter night behind my apartment in Oklahoma City in 1984, as I pointed the little 60mm at a bright “star”, and focused it in. I literally GASPED out loud as the rings of Saturn came into sharp detail. That was it......I was hooked for life!

Everyone is a little different, sometimes a LOT different, but the next logical step for learning how to get all you can from your telescope is to use a good set of star charts. I say set because I personally believe its impossible to produce a single star chart with everything on it. But how detailed do YOU need a set of charts to be? We should probably start with the same charts I started with, which is the monthly centerfold chart of Astronomy magazine. (Sky & Tel has similar charts) These charts have their good points and their bad points, and I'll try to explain why I find this to be.

At the time I seriously started into astronomy in 1984-1985, locating things from charts was done by visually identifying certain stars in the sky and on the charts at the same time. Too small of a chart didn't allow for many more stars to be included that are sometimes crucial to finding what you're after. The larger the chart the more dim stars are depicted on the chart and that means many more smaller stars that you'll see in the night sky from a dark location.

Planispheres are neat little rotating "wheels" that can help orient the user to see what's up for tonight, or six months from now, and at any time of night. Together with the centerfold charts, they allow for much better understanding of what's going on at any time than either the centerfold charts or the planispheres by themselves ever will.
Case in point: A triangular pattern of dim stars isn't shown on centerfold charts because they're too small....the stars of the triangle are too dim. But the larger chart does show them along with the tiny oval almost dead-center of the triangle which is the next object you need for your list of selected targets. I may not have found this dim little oval galaxy with just centerfold charts. If I hadn't gotten my Sky Atlas 2000, I could've possibly STILL been trying to find some of my Herschel 400 objects. Those stars were just barely visible in a dark sky and the little galaxy at the center was easily found and recorded. That's the star-hop method .....comparing stars shown on a chart with what is actually SEEN in the night sky and carefully moving your telescope towards a certain star or pattern of stars to bag your quarry. Its easier than it sounds, too!

My Good Points on "Centerfold" Charts
First, these charts are a FREE inclusion in several magazines each month. They also reveal the changing appearance of the sky as the months pass by over a year's time. The reader sees how the constellations are forever marching towards the west, while new constellations keep appearing on the eastern horizon and replacing what sets in the west. That was something that really grabbed me at the very outset of my self-taught course on amateur astronomy.

Click Read More for the rest of the story, and for more suggestions on other star charts.

They also have very good suggestions on what you can see for any given month, and they usually include all the telescopic "Best Of" objects listed for you to try locating with your telescope.

Tirion's "Sky Atlas 2000" is a favorite of many amateur astronomers as their primary star charts.
This info is sometimes included as a full article to supplement the charts. They also introduce the user to the standard symbols for the various objects, such as open ovals for galaxies, a cross inside a circle for globular clusters, etc. Unfortunately, these simple charts have their down-sides, too.

My Bad Points of "Centerfold" Charts
While I did use these charts with my earliest telescope, I needed better charts very quickly and it was then that I was first introduced to how one chart differs from any others. The charts in the centerfolds of magazines pretty much all represent a night sky for a certain time of night for each month.The bad part about this is that it forces the user to read very carefully the instructions on how they should use these charts. Around the border of the circular centerfold charts are illustrations of the horizon.The horizon of centerfold charts are embellished with trees, buildings, houses, and other identifiable objects. It should be thought of as a deep half sphere, a hollow ball that users must turn around the circle with the border to the East held down when you want to locate an object in the East which may have just risen. Likewise, if another object is in the west and low to the horizon, the user must again hold the charts with the "W" edge of the horizon down at the bottom while facing west and imagine gazing up into the bowl of night. The center of the chart is what's directly overhead, and everything near the edge is close to the horizon. That means everything else is located wherever it is depicted on the chart, but you must remember to hold it up above you while you turn the chart around on its edge and face in that specific direction for EVERY object you choose to hunt for, which I find to be frustrating at times. If you haven't realized my next point here, think about this.....the ENTIRE night sky (for a time period of about 2 hours) is in that all-too-tiny circular chart from the centerfold of some magazine! That's the biggest reason of why I looked at other star charts.....I needed something that represented the sky in a scale somewhat closer to what I was looking at in the night sky.

The "gold standard" for a number of years in the 80's and 90's was the Sky Atlas 2000, produced by stellar cartographer Wil Tirion and first published in 1981. These charts were of certain specific areas of sky on a MUCH larger scale than the centerfold charts. Each page is about 13.5"-by-18" and the 26 pages cover the entire sky, north AND south of the equator. These charts give very accurate positions of more than 2,500 deep-sky targets and nearly 43,000 stars! Now, I really was ready to start locating objects.

I went on to finish my Messier Object list and eventually my Herschel 400 list using my Sky Atlas 2000. I still love it and depend on it whenever I'm not using any of our computerized telescopes. To me, using a computerized telescope to locate objects by pushing a button is cheating. Anyone can do that, but it helps secure our belief in our own abilities when we use the old-fashioned way of locating objects, by using charts and the star-hop method of location.

There are new charts coming out fairly regularly now. Astronomy and Sky & Telescope both have charts that were made especially for them, and the prices are very reasonable. I've seen both and I'd feel comfortable using either one to locate objects by star-hopping.

Ultimately, though, it comes down to the individual and their choice of which is better for them. Which one is the right size of chart, the right ease of use, or the right "feel" for lack of a better term. AOAS has some of these charts and members can use these to try and help them determine which they'd be happier with owning. The charts are the next most important item in learning how to use your new telescope right behind the finderscope. Which one is right for you and the way you want to use your telescope?

Comments (1)

AOAS.ORG
http://www.aoas.org/article.php?story=20070524000319274