Rating: 

The team of Robert and Barbara Thompson, who produced the excellent "Astronomy Hacks" in 2005, have come up with a superlative book for beginning to intermediate deep sky observers entitled, "Illustrated Guide to Astronomical Wonders".

Taking the objects from six well-known observing lists:

= the Messier objects,
= the RASC (Royal Astronomical Society of Canada) Finest NGC objects
= the AL (Astronomical League) Binocular Messier List
= the AL Deep-Sky Binocular List
= the AL Urban Observing List
= the AL Doubles Star List

the authors present 400 outstanding objects, all well within the range of moderate apertures (the largest scope referenced in their book is a 10" reflector). So, while challenging, the number isn't overwhelming and the objects aren't too difficult.

The objects are sorted into fifty constellations available to northern observers, each given a chapter and presented alphabetically. Each chapter contains:

= A discussion of the constellation

= A full constellation chart showing object locations.

= Tables giving:
- type, size, magnitude, coordinates, etc for each
object
- the originating observing list (Messier, RASC, AL) from
which the object was taken

= Finder charts for each object with uniform 5 degree or 1 degree
circles superimposed, making them adequate for field use

= Individual discussions of each object. Each discussion also
contains a description on how to find the object, as an example,

"...The easiest way we found to locate NGC 7129
was to place mag 4.4 xi on the SE edge of our
finder field and look for mag 5.4 7-Cep which
appears near the NW edge. NGC 7129 lies on a
line between those two stars, about two-thirds
of the way from xi to 7-Cep..."

= Uniform 1 square degree black and white photographs of almost all of the deep sky objects. These small images better approximate what a visual observer might actually see at the eyepiece.

= Each object also bears a four level visual rating, ranging from unimpressive to showpiece and a four level finding difficulty rating, going from very difficult to easy to find.

To those acquainted with the larger, more expensive two-volume Night Sky Observer's Guide, this chapter format will look familiar,the significant difference being that the NSOG chapters list a selection of variables in each constellation.

Of course the 400 objects of the Thompson book is dwarfed by the 5,541 of the NSOG, but that smaller number in the Illustrated Guide allows it to include more practical finder charts and to better address amateurs equipped with moderate apertures under less than ideal skies. For example, some of the NSOG descriptions only list what you'll see in fairly large scopes, 16 to 18 inches. That's not helpful to many amateur observers.

The first sixty or so pages of the Illustrated Guide contain an intro to DSO observing and a discussion of observing equipment. Both sections are very informative and actually enjoyable because, surprise, they address the concerns of a real practicing amateur observer.

For example, you'll find pointers on how to plan observing sessions but you'll also find things that'll move you off the level of a beginner right away, for example, a description of the Trumpler scale for open clusters and a discussion of perceiving color in blue-green O-III light.

Equipment wise, the Thompsons aren't shy about noting their preferences, for example, their favored planetarium software is Megastar. But they also objectively discuss the pros and cons of telescope types, individual eyepiece lines and the performance of different nebular filters.

The book aims to supply some of the practical wisdom that observers usually have to pick up the hard way - spending time under the night sky and patiently distinguishing the useful from the irrelevant and the hype.

Physically, the Illustrated Guide is an attractive paperback that opens flat and has generous margins on each page for jotting notes.

So general strengths of the book? The Illustrated Guide is a reasonably priced, one-volume guide to deep sky observing written by a knowledgeable observing team that can become a mainstay of any amateur library. Using just this observing guide, a beginning observer could become a relatively advanced amateur in a reasonably short period - yes, I think it's that well designed. For some observers, it might actually make up their entire observing "career".

Urban astronomers may find the black and white images invaluable in helping to identify objects like open clusters that might normally go unrecognized in light polluted skies.

Also, with some qualifications, viewing all the objects in this book will fulfill the requirements for a number of observing certificates, if that's one of your aims.

OK, weaknesses? Well, none really. But something said by the authors in their introduction bears repeating. Amateur astronomy has become almost synonymous with deep sky observing. And that's unfortunate.

Planetary and variable star observing each require different types of observing skill and often different types of equipment. Until excellent guides like the Thompsons' new book are devoted to these branches of amateur astronomy, many people will continue to ignore them.

John Cheng
Pittsburgh PA