The Caldwell Objects

out of order with respect to declination; the
cluster should be listed between NGC 7814
(Caldwell 43) and NGC 7479 (Caldwell 44).
Caldwell 49. The designation of the Rosette
Nebula as NGC 2237-9 is incorrect; the Rosette
comprises NGC 2237, NGC 2238, and NGC 2246.
Caldwell 89. The S Normae Cluster is not NGC
6067, as originally published in Sky & Telescope,
but NGC 6087.
Caldwell 100. This entry was originally labeled
"IС 2944" and "Gamma Centauri Cluster." But
this identification is quite garbled. First, there is
no Gamma Centauri Cluster; the name should
have read "Lambda Centauri Cluster." But that
alone doesn't fix the problem, for in the Index
Catalogues IС 2944 is a nebula, not a star cluster.
(Steven Lee and David Ratledge came close to
solving the puzzle of Caldwell 100's designation
in the June 2000 issue of Sky & Telescope, page 12,
but even their informative discussion didn't close
the case on Caldwell 100. See Chapter 2.)
That's just the tip of the research iceberg.
Once I started accumulating historical and
observational information on other Caldwell
objects, more problems materialized; their solutions
are detailed in the appropriate sections of
the next chapter.
One more concern. Throughout the book I
will refer to several star atiases: Wil Tirion's Sky
Atlas2000.0 (both the first and second editions),
Uranometria 2000.0, the Millennium Star Atlas, and
more. Why? Just as there are inconsistencies
within the historical record and the amateur literature,
so too are there problems with these star
charts (omissions, misplottings, etc.). Since I have
no idea which star charts you own, I often
14
take the time to tell you which objects appear on
which atlases, and what was omitted or misplotted.
You shouldn't have any problems with
the star charts in this book, of course, and they
alone should enable you to locate all 109
Caldwell objects without having to resort to other
atlases.
THE FINDER CHARTS
As noted above, finding a Caldwell object that
you've never seen before is a three-step process.
First look up its celestial coordinates (its right
ascension and declination) alongside the object's
description in Chapter 2, or in Appendix A. Next,
use those coordinates to find the object on the allsky
star charts located on the endpapers. The allsky
charts depict the constellations much as a
planisphere would, and they should tell you at a
glance the general direction in which to look
(assuming your chosen object is above the
horizon). Finally, return to Chapter 2 and look at
the object's detailed finder chart. That chart will
have at least one Bayer (Greek-lettered) or
Flamsteed (numbered) star in common with the
all-sky chart. Beginning with that star, which
should be visible to the naked eye from all but
the most light-polluted sites, you can star-hop to
the Caldwell object, either by following the route
described in Chapter 2 or by blazing your own
trail.
The detailed charts in Chapter 2 are outwardly
similar to Wil Tirion and Roger W .
Sinnott's Sky Atlas 2000.0, second edition. Like the
Field and Desk editions of that work, they have a
scale of 3.55° (3° 33') per inch (or 7.1 mm per
degree), and they depict stars as faint as
magnitude 8.5, providing a generous density of
stellar "stepping-stones" for a wide-field
telescope. North is up and west is to the right
throughout (though for objects that lie near one
of the celestial poles there is some distor-
Deep-Sky Companions: The Caldwell Objects