Astronomy book reviews

The Practical Astronomer's Deep-Sky Companion

(Patrick Moore's Practical Astronomy Series)

by Jess K. Gilmour
Published by Springer-Verlag London
ISBN: 1-85233-474-6

or follow the link The Practical Astronomer's Deep-Sky Companion if you want more info first (before buying it)

Bookcover The Practical Astronomer's Deep Sky Companion


Jess K. Gilmour is an amateur astronomer from Ontario, Canada, who has been observing and photographing the night sky for 25 years. As an owner of a new goto-telescope he wanted to create an observing list of deep sky objects for his personal use. He did this by selecting about 400 objects from a constellation-by-constellation research of thousands of deep sky objects, visible from his different viewing locations throughout Ontario.

The objects where selected by four different criteria: visual presentation, photographic splendour, obscurity and sky track. They also had to be observable with popular commercially available telescopes with apertures ranging from 4 to 12 inch. The final list is represented in this book.

The Book

On first sight, I was very impressed by "The Practical Astronomer's Deep-Sky Companion". It comes in a water resistant cover for outdoor use and holds 140 pages with more than 800 maps and images in full colour. The 400 deep sky objects are organised by constellation in alphabetic order. Within every constellation you will find a variety of observable objects from different catalogues, Messier, NGC, IC, Barnard's dark nebulae, Sharpless catalogue of HII regions, and one or two others. This makes the book interesting for beginning as well as for advanced observers. And that is exactly what Jess states in the introduction of his book:

"As the idea for this book came into focus I decided early that it would have no precisely defined target audience, but contains a cross-section of information required to track down and observe objects whether you are a beginner or advanced observer".

Contents of book

sample page 1

Example page book

sample page 2

Every chapter (constellation) starts with an overview map of the constellation. The deep sky objects which are discussed in the particular chapter, are plotted on this overview map. The objects are represented by symbols in different shapes and colours. I’ve tried reading the maps under dark skies, just using a red LED flash light. The symbols could be recognized easily under these conditions, because of the difference in form and size. Very well thought off. On the same page as the constellation map you will find a legend of the symbols used, the latitude from where it is visible, number of degrees of sky the constellation covers, sky track, when it covers the meridian, the optimum season for observing and the correct pronunciation.

Following the constellation page are the pages with the different deep sky objects. For every object you will find detailed information:

Name: The catalogue number(s) and common name of the object
RA: Right Ascension coordinates (Epoch 2000)
DEC: Declination coordinates (Epoch 2000)
Size: The size of the object in arc minutes
Con: The constellation within which the object is located
Type: The type of object
Mag: The visual magnitude of the object
Notes: Short notes about the object to aid in locating and/or observing it

Contents of book

sample page 3

Contents of book

sample page 4

Below the object data you will find two additional fields with information, Telescope aperture and FOV (35mm film). These fields are the same for all the objects in the book (maybe a lot of useful space has been wasted here). The telescope aperture field contains a table with telescopes of different apertures and focal lengths. The field of view (FOV) field contains in arc minutes, the major and minor axes of the field of view, corresponding to the telescopes. In the table. Both fields combined with the values of the major and minor axes of the object (size field in object information) should give you an idea whether or not a particular object fit’s a 35mm negative. I’m no real Astro photographer so I cannot comment on the usefulness of these fields for the (CCD) photographers out there.

To the left of the object data you will find a small locater chart of the object. They are simply to small and of little or no use, but if you are a serious deep sky observer you probably own a sky atlas like the Uranometria or the Sky Atlas 2000. I always use the laminated field version of the Sky Atlas 2000, in combination with my observing handbooks. They go together well.

To the right of the object you will find a colour image of the object. The images are really beautiful, but again a bit small. They are only 49mm x 33mm, but they give the observer an idea of how the objects really look like. They do not show what to expect at the eyepiece. I had a look at the photo’s just using a red LED flashlight. All the images seemed more or less black and white, but they objects on it were still easy to recognize. It’s a pity that the book doesn’t contain any data on the images.

The book ends with an index on all objects.

Example page

sample page 5


Taking everything into consideration, I find this book very useful during my observing sessions.

It is made for outdoor use, it provides relevant basic data for every object, and the entire book (including all the maps, images and symbols) can still be read under dark skies, using a red flashlight. The finder (or locator) charts are too small, but I don’t see this as a real problem. Most deep sky observing guides come without detailed finder charts. As a deep sky observer you should own a good sky atlas or even better, astronomy software to print your own detailed maps.

Of course you can use the book for preparing your observing sessions. "The Practical Astronomer's Deep-Sky Companion" is reasonably priced. If you are a deep sky observer, beginner or advanced, and you are looking for a ready to go observing list for outdoor use, then I can recommend this book highly.

I would like to thank Springer Verlag London for granting me permission to add a few sample-pages to my website.

Copyright © 2003