The Caldwell Objects

emains of a globular cluster that was torn apart
by tidal forces. Sweep your eyes across the field
at low power and see if the entire region doesn't
look as if you're viewing it through a black fog.
That's because the entire region is veiled in dark
nebulosity. The extinction of starlight by dust
must be substantial along this sightline through
our galaxy's disk.
At 72x the cluster's dual aspect is most
apparent. Also, look for two asterisms resembling
the Southern Cross interspersed among
several groupings, pairs, and strings of stars.
Ernst Hartung called NGC 6124 a "scattered
galactic cluster . . . [with] several orange stars as
well as numerous pairs, triplets and small
groups." I did not note any colored stars. Do you?
If you throw the cluster out of focus it looks like a
barred spiral galaxy with a large dust lane slicing
through the bar and core, or a shield with a coat
of arms.
The magnitude-10.9 planetary nebula
The Caldwell Objects
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NGC 6153 lies just a little more than 1° eastnortheast
of NGC 6124. The 25"-diameter object is
easy to see once you point your telescope in the
right direction. It's the southernmost "star" in a 5'wide
diamond-shaped asterism of 9th- and 10thmagnitude
points of light. NGC 6153 is an
annular planetary nebula with a magnitude-15.4
central star. In the 4-inch the nebula looks like a
swollen star at moderate magnifications. And
nearly 2° north-northeast of NGC 6124 is the
small but bright (magnitude 9.0) globular star
cluster NGC 6139, which I found once on a comet
sweep. Before leaving the area, do sweep that
region I mentioned earlier, southeast of the
Scorpion's Tail, toward Norma, and see how
many tiny open star clusters and asterisms you
encounter. You'll be taking a fantastic voyage
through some of the most spectacular Milky Way
regions, one that is guaranteed to keep you
occupied on many a moonless evening.
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