John Baars

First impressions of Interstellarum Deep Sky Guide, a short review.

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by , 11-24-2018 at 12:53 PM (319 Views)
Quote Originally Posted by John Baars View Post
Interstellarum Deep sky Guide.
After waiting a long period of more than six months, it finally arrived. My copy of the IDSG. I had ordered the desk edition. English version. I never take an atlas or a guide out in the field any more, since I make my wish-list at home, accompanied by an atlas ( IDSA), a guide and a cup of coffee. Out in the field my cellphone-app SSPro is my buddy. Until two years ago I took my atlas with me in the field, nowadays I consider a nice atlas and a good guide as the perfect buddies in the warmth of my living-room. Anticipation is part of the hobby.

The first real atlas I ever bought was Norton's. The Interstellarum Deep Sky Atlas ( German version) was the most recent one. One of the best too. The last Guide I bought was the Stropek Deepsky Beobachteratlas. But when I heard about the IDSG, I knew I had to have that one too, since it forms a perfect couple with the IDSA.

The dimensions are all right, the ring-binder allows it to make it an 11X11 inch format, so it still can be put on any observers's chair /table. The waterproof Field-edition will feel better at home there.

The two introduction pages give account of the chosen methods and choices, and contain a brief manual.

Ranking and finding objects.
Like in the IDSA the objects are chosen according to their visibility ( experienced observer) and useable telescope size (4, 8, 12 Inch and Challenge for bigger) under moderately dark skies. Bortle 4-3. This is a pleasant and accessible way of ranking, since one doesn't have to wonder and calculate if the object will be visible.

Each set of pages has a numbered list of objects ranked by telescope-aperture and an inset, mostly on the right side. The list contains the objects and a very short description of it. The inset shows the position of the objects in the ISDA on the matching pages. The IDSG pages are oriented the same way as the IDSA. This makes it very easy to compare the Atlas with the Guide. If you just superimpose them, you'll have an overview at one glance. Quite a relief as most guides give you a hard time on finding your object in the atlas and vice versa. This new approach looks a bit like the Stropek, but is more clear.

Each page contains pictures and sketches.

The 1729 images are the main feature. They are composed by combining blue and red plates from several surveys. This was done on purpose, since shining on them in the dark with a dimmed red light, makes the red image dissapear, and the blue image come forward. Like observing with our dark adapted human eye on 510 nanometers. In daylight the effect can be reproduced with a red coloring filter. In the Guide- images stars are encircled that you can find in the Atlas. Makes it easier to orientate and starhop / search. Every photograph has a small blue scale bar in the right corner of one arc minute across. I find that feature very helpful in estimating the size of what you are going to observe.

The 821 sketches are all in black on white and drawn by the two writers / observers Ronald Stoyan and Uwe Glahn themselves. These are certainly not "at first glance" sketches, but made by experiences observers and sketchers doing their utmost to retract details from the fuzzies they saw. Each sketch has the initials of the maker, the size of the instrument, the magnification and any filter used. Some sketches like those of M57 and NGC6888 go as deep as magnitude 15.5 or deeper with instruments of 14, 27 and even 48 inch!

Accessibility is made easier with the list of catalog abbreviations on page 0, the index of nicknames and the index of DSO's by catalog numbers on the last pages. The very last page has a list of the constellations and a small list of errata in the IDSA.

Points of criticism?
The ranking for visibility is done according to the aperture under Bortle 3-4 skies. That is a choice. For Urban or suburban observers the visibility of some of the objects may be a bit to optimistic. As an observer you have to take that in account.
The list of objects given at the right upper corner of the pages could perhaps give a bit more information like apparent magnitude. A bit of peanuts perhaps.....

It is amazing how nice the Guide matches the Atlas. Never seen this before. This is an outstanding piece of work, suited for any advanced and experienced visual observer. Photographers will find more than enough inspiration for new objects. And even the most stubborn hard-core faint-fuzzy-hunters will leave their Uranometria Atlas and Guide more often in the library and use them just as a reference-book. Instead they too will more and more look for new objects in the IDSA and Guide. For me it was love at first sight....

An observers' relief.
As some of you know I do some sketching from time to time. Last holiday I sketched NGC 6888, the Crescent under a Bortle 4 sky through a 5.5 inch Maksutov. When I received the Guide I wondered how Ronald Stoyan and Uwe Glahn had done that. As a matter of fact the sweat was on the forehead when I openend page 17b, where NGC 6888 was to be found. Ronald Stoyan had seen more details with his 14 inch telescope, as to be expected. But the overall view was about the same. Pffff...quite a relief!

Thanks for reading.
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