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Planning an Observing Session

by John A. Barra

Books Recommended by John:

Star-hopping for Backyard Astronomers by MacRobert

Observing the Constellations by Sanford

Peterson Field Guides: Stars and Planets

The Audubon Society Field Guide to the Night Sky

The Observer’s Sky Atlas by Karkoschka.

The Messier Album by Mallas and Kreimer

Messier Marathon Observer’s Guide by Machholz


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Lessons One through Four appeared in Starlite Issues #128-131, December 1996-September 1997

There are two rules in planning an observing session: make it simple and make it fun. In other words, your planning should help you spend the night enjoying objects rather than struggling to find them.

DECIDING WHAT TO VIEW

To decide which objects to view, obtain a planisphere to see which constellations will be observable that night. As a beginner, you may not feel confident to decide which objects to view. I suggest getting a beginner’s book that does the planning for you.

MacRobert’s Star-hopping for Backyard Astronomers is an excellent choice. He picks different areas of the sky and chooses ten or twelve objects in each section that are close together and within the range of the beginner. His sky charts and descriptions of the objects lead you through the session. Turn Left at Orion by Consolmagno and Davis is another good book. The deep sky objects in it are arranged in the order they appear in the sky. While its charts are not as easy to follow as MacRobert’s, the drawings of how the objects look in the eyepiece are quite helpful.

Another method is to pick a constellation and view the deep sky objects within it. I found the most useful book for this method is Observing the Constellations by Sanford. This book includes a chart of each constellation along with locations of the objects, a list of each prominent object with parameters such as size and magnitude, and a description of the best ones to view. Similar books I have found useful are Peterson Field Guides: Stars and Planets, The Audubon Society Field Guide to the Night Sky, and The Observer’s Sky Atlas by Karkoschka.

A common way to choose objects is to use the famous Messier list. All the books I’ve mentioned include the Messier objects. Just pick which ones you’d like to locate each night. I have found The Messier Album by Mallas and Kreimer and Messier Marathon Observer’s Guide by Machholz quite helpful in planning many Messier viewing sessions.

Finally, as you gain experience you may want to obtain the 3-volume Burnham’s Celestial Handbook. While it doesn’t contain star maps, it provides a tremendous amount of information on many objects and will help you choose targets for later observing sessions.

PREPARING CHARTS

Most astronomy books (like the above) unfortunately are not good books to use in the field. You’ll need a good field atlas at the viewing site to aid in finding the objects you have chosen. There are many available; I personally use Sky Atlas 2000.0 by Tirion. Its charts give the locations of most of the popular deep-sky objects. My laminated version is very handy for field use.You can also create your own star charts.

You’d be surprised how effective they can be. Draw the bright, easier-to-locate objects and their constellations, or use a computer and one of the many starchart-making programs available to print your charts. Put your charts in clear page protectors, snap them in a three-ring binder; you’ll have a great field book.

I use the program Star Navigator given with Meade telescopes. First I make a chart with a wide field of view. I locate the constellation and the object, and mark the closest naked-eye star to my object. Then I make a close-up chart containing the target star and my object.

Most programs are not good at reproducing the fainter stars, so I make use of my favorite resource, the two-volume Uranometria 2000.0 by Tirion, Rappaport, and Lovi. Big and hardbound, Uranometria makes a lousy field book. However, it contains thefainter stars and as many deep sky objects as you would ever want. I locate those stars that are between my target star and the object and add them to my close-up chart. Other people have made great field charts by copying portions of pages from Uranometria and putting them in page protectors or laminating them.

DOCUMENTING YOUR VIEWING
SESSION

As always, you’ll want to document your observations. Some objects are verifiable merely by looking at them. However, many of these objects are dim; you can’t always be sure you are looking at what you planned to. I always draw the object and the stars I see with it in the eyepiece. A folded piece of paper or a notecard works fine.

Your drawings need not be exact; just show the object in relation to the stars nearby. When you get home, you can compare the rough drawing to the photographs or star charts in the books you have. If you have access to the Internet, try using the Digitized Sky Survey <http://stdatu.stsci.edu/dss/>. It contains photographs of the entire sky with all the deep-sky objects and the stars around them. The stars seen in most amateur telescopes appear bright and slightly spiked in DSS, making for easy comparison with your drawing.

Finally, memorialize your observing session with notes and descriptions in your star journal, as simply or as detailed as you want.

You may wonder when you’ll have the time to look through the books, choose objects to view, and make your field charts. Remember all those cold winter nights or the many cloudy nights the rest of the year. That’s when you plan for the few good seeing nights to come.

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Lesson Six: Tips on Participating in the Messier Marathon




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