The Caldwell Objects

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The Horseshoe Cluster
NGC 663
Type: Open Cluster
Con: Cassiopeia
RA:01 h 46.3 m
Dec: +61° 13'
Mag: 7.1;
6.7 (O'Meara)
Diam: 15.0'
Dist: 7,200 light-years
Disc: William Herschel, 1787
W. HERSCHEL: [Observed 3
November 1787] A beautiful
cluster of pretty [bright] stars
near 15' diameter.
Considerably rich. (HVI-31)
GC/NGC: Cluster, bright,
large, extremely rich, stars
pretty [bright].
TO THE TELESCOPIC TRAVELER,
the open clusters that adorn the
Cassiopeia Milky Way are like
pale wildflowers along a
country road. Anyone with
modest equipment can find
some five dozens of them
planted in the constellation's
598 square degrees of sky. Most
congregate around that
busy highway of stars, the galactic equator. One
particularly rich section lies only 2½° eastnortheast
of 3rd-magnitude Delta (δ) Cassiopeiae
in the constellation's famous Μ (or W) asterism.
Here you will find five dramatically different
examples of these loosely packed stellar
agglomerations. They are, in order of equinox
2000.0 right ascension: M103, Trumpler 1, NGC
654, NGC 659, and NGC 663.
The Caldwell Objects
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When seen through binoculars or a rich-field
telescope, these clusters form an incomplete 2°wide
circle around a diamond of roughly 7thmagnitude
stars.
Glimmering at 7th magnitude, NGC 663
(Caldwell 10) is brighter, but not more famous,
than M103, itself a Christmas-tree-shaped cluster
glistening with stellar ornaments about 1½° to
the west-southwest. Messier objects have
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