When I compare star charts to see which to purchase, or to use
on a given cccasion, I use the following criteria:
1. Faintest stars shown. On this basis, the Peterson Guide, Pasachoff,
Stars and Planets, bests all other compact books since it goes to
magnitude 7.5. Scale is small, but a plastic loup that sits on the
charts will make it more readable, at least at a desk.
SA 2000 original edition goes to mag 8, and SA3000 revised goes to mag
8.5, about doubling the number of stars shown, a big help.
The limiting mag for the Night Sky Observers' Guide finder charts,is
said to be mag 9, more than doubling the number of stars, I estimate,
of SA2000 Revised. To see this visually, I always examine the region
near Eta and Zeta Scopii.
The new versions fo the Astro Cards, are computer drawn rather than
by hand unlike the earlier edtion. The mag limit is stated to be 9,
but I find it shows many more stars than the NSOG finder charts.
2. Number of objects shown. Pasachoff greatly exceeds othr books
here too, but the charts in SA2000 has still more.
3. Contrast when viewed at night. Here the yellow stars on blue
backgroud Moore and Tirion book, the Cambridge Guide to the Stars and
Planets, excels. Paschoff is not very readable by me under red light
For reasons of low contrast, the earlier Ridpath and Tirion Collins
Guide to the Stars and Planets,is bested by the other books.
Deep Map 600 is even more readable under red light than any of the
above books.
4. Commentary. John Sanford, Observing the Constellations, uses the
same maps as Ridpath and Tirion but accompanies the charts with much
more extsive commmentary and descriptions, so it easily bests the
Moore and Tirion book. Pasachoff has good commentary as well but not
as good as Sanford.
5.Contiguity. If a chart shows a constellation but doesn't show
objects in adjoining constellations even though the objects are only a
very small distance away, it is harder to use. Paschoff doesn't make
this error but Ridpath and Tirion, Moore and Tirion, and Sanford do.
6. Scale. Deep Map 600 has a larger scale than any of the books
mentioned and I prefer it to them for that reason. It has some
commentary as well.
7. Included objects. I apply a Scorpius test, a Sagittarius test, and
a Canis Major test, to evaluate selection of objects. I look to see if
NGC6231 is included, and if 6302 (The Bug Nebula) are included in
Scorpius, and if 6822 and 6828, two globulars in Sag thar are very
close the the center of our galaxy, are included. I look to see if
h3945, one of the great double stars, is shown and labelled, in Canis
Major. Deep Map 600, the new AStrocards, and SA2000 Revised score well
here.
8. Naming. I look to see if 6302 the Bug Nebula is named on the chart,
and if NGC 6822 is named on the chart.
9. Scale. The new Astrocards have the same ;arge scale as SA2000 , a
big plus for both. it is slightly smaller scale than the SA2000
Revised, Deluxe Edition.
10. Portability. It looks like the New AStrocards, plus the reader for
them, will go to the Shingletown Star Party with me. Also, as a
backup, some sheets from SA2000 first edition, removed from the
binding and folded in the way one folds a road map, accordian style,
an idea I got from an article by Tony Flanders.
11. Aesthetics. Erich Karkoschka's fine little book, The Observer's
Sky Atlas, is very compact and goes to mag 9 in its finder charts. It
is a good alternative to the new Astrocard plus charts from SA2000
combination described above though I am not enthusiatic about it from
an aesthetic viewpoint. I might take the second Edition to
Shingletoown with me.
Ciao,
Bill Meyers
