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A review of The Cambridge Star Atlas

Posted by Ed Moreno   01/28/2009 12:00AM

Look back.. Way back.. Look back.. Past Uranometria . Back PAST the Sky Atlas 2000, back past the very DAWN of time... Oops.. I am getting carried away... Ok.. Lets look back about 17 years.. That isn't so bad. Look back to before computerized telescopes were the norm, before desktop planetarium software was better than what planetariums use, and when charts were not highly detailed works of art.

And what you will find is the Cambridge Star Atlas, a sweetheart of a book. This was one of my very first Atlases, and the reason for this review is to present its virtues.

Often, I think new observers jump in too deep with charts that contain far too much in detail in terms of potential targets. The problem is that on charts like Sky Atlas 2000, there TOO MANY objects! See, Sky Atlas 2000, and many planetarium programs tend to indiscriminately show just about all major catalog items down to limiting magnitudes that simply are not practical as targets for small telescope. Also, while SIZE is indicated for many targets, MAGNITUDE is NOT (at least on hard paper charts).

The situation for double stars is that there is typically no information on most hard-charts.. You know that it is a double because of the little line though the star symbol, and you know the brightness of the primary, but you don't know diddly about the secondary magnitude or separation.

So, what is an observer to do? They can make a lot of notes in advance, or they can tote out a computer. Well, another choice exists, and that is to get it all in one in an EASY to use format. The charm and appeal of the Cambridge Star Atlas is exactly that. So with that, let me give you an overview of this wonderful observing companion.

The Cambridge Star Atlas is a relatively thin and light volume.. It is only about 90 pages, and the format is 12" tall by 9" wide when closed.. This small form is an advantage in many ways because even open, it only takes half the space of Sky Atlas 2000.

The book is organized into several sections. The first section is a two page map of the moon. Now this in itself is actually quite handy because many other charts completely ignore the moon. This one lists 249 different features. No, not a GREAT moon atlas, but at the same time, if you want to find a minor crater like Plinius, or locate a wonderful feature like Triesnecker (one of my FAVORITE lunar features), the chart do that. 249 Is a fair number of objects to identify and for most newer observers, is sufficient to navigate around the lunar landscape.. So, this chart is not all that great, but it is in the book, and I have used it a fair number of times.

The next section is a list of monthly sky charts. This information is actually pretty basic, generally just showing a page for each month, with stars down to Mag 5, and constellation stick figures. There is a short three entry table at the bottom of each page that shows the month and time that the chart would show the sky as depicted. For example, on the January page, the little table says that the sky will appear this way on January 1st at 11PM, January 15th and 10 PM and February 1st at 9 PM. Two other nice features are that each chart has horizon latitude lines to show you where the horizon is for the observer’s latitude, and get this, there is a SOUTHERN OBSERVER chart. So for each two pages, one shows the northern sky, and one shows the southern sky. I am SOOO delighted that my Aussie friends are covered here!

The heart of the book in my own opinion is the Star Chart section. It starts with a couple of pages that explain the content and things like how Magnitudes are “Binned”. Next, it provides a table with all of the constellation names, genitives, abbreviations, common names, and chart number. Another couple of pages provide info on categories of targets and one page of abbreviations used in the charts. Next in the Star Chart section is an index chart that shows the entire sky with pie shaped wedges numbered to reference you to specific charts.

And now to the charts themselves and the feature that I believe makes Cambridge such a WONDERFUL observing companion to a small scope. The real beauty of the Cambridge book is that the format for the main char pages is so user friendly! First, the charts tend to cover fairly large sections of sky, and they tend to present ONLY targets that are what I would call “Excellent” targets. By this I mean that these charts tend to focus on the brighter targets in the sky. If you have a small telescope, too many of the objects on more detailed charts are simply too dim to get much from. On the other hand, if it is charted in the Cambridge Atlas, it is probably a fairly good target for up to about an 8” scope. A GREAT number of the plotted targets are even good targets for a 4” refractor!

Ah, but that is not the BEST part.. To me, the BEST part is that on the page across from each chart is a set of TABLES. These tables identify the best Variables, Doubles, Open Clusters, Planetary Nebula, Nebula, and Galaxies that appear on the chart! Each table presents information relevant to that type of target. For example, the Open Cluster table provides NGC number, right ascension, declination, diameter, magnitude, and number of stars!

As an example, Chart 2, which covers an area of sky that stretches from Perseus to Andromeda and from about +15 degrees declination to about 65 degrees Declination.. The accompanying tables for this one chart list 9 variable stars, 27 double stars, 23 open clusters, one planetary nebula, 3 nebula, and 12 galaxies! Now the REASON that this is so handy is because if you see an object on the chart that looks interesting, like NGC 976, you can quickly locate it in the table and find out that it is magnitude 12.4. This might be too dim for your scope, so now you know that maybe it will not be worth your time to train your scope on it. Or conversely, you might look at the table and see that NGC 1027 is a is 20 arc minutes in diameter, magnitude 6.7, and contains 40 stars and determine that it is a GREAT target for your size telescope! THIS is what makes Cambridge so valuable. With conventional charts, you simply don’t get most of this information. And with many pocket guides, you are forced to flip back and forth between tables and charts. With Cambridge, all of the information on hundreds and hundreds of the brighter sky objects is presented in a most observer friendly format! Just about everything that constitutes a really good target for each chart is cataloged along with enough information to help you with your observing!

The final section of the book includes several “All Sky” maps. While these are not necessarily useful for observing, the are interesting for showing distributions of objects like clusters, globular clusters, and open clusters across the entire sky (there is a separate chart for each). I can’t say that I have used these much, but I have indeed looked at them on occasion.

Ok, it is not all that fancy. And the charts don’t have the “Dazzle” of major works like Sky Atlas 2000.. But don’t be fooled by a pretty face. These charts often contain more targets that are NOT rewarding or in most cases, NOT EVEN VISIBLE in small telescopes. To be fair, even Cambridge has targets that would push a 4 inch scope in all but very dark skies. Still, the BEAUTY is that because of the format of the book, it is SIMPLE to determine if a target is worthy of the time it will require to find it, and if you don’t KNOW what you want to see, it can show you at a glance all of the better objects available to you in one section of sky.

If you are a novice looking for a great entry level atlas, or a seasoned big dob user that wants a green, low tech way to compliment your 4” grab-and-go, don’t overlook the Cambridge Star Atlas. It is a wonderful observing companion for just about any level of observer.

Bottom line? A true classic. It is inexpensive, and user friendly. I think it is a better observing guide than just about anything else around for novices, and a handy book for even the most experienced observer that needs a small scope companion. Highly recommended.

My challenge? Get one and put a pencil check mark next to every object that you locate and observe with it. My bet is that it will take you a while to check every object visible from your observing location. And when you HAVE, I would welcome you to the ranks of the most experienced observers out there.