The Caldwell Objects

pointed her 7x35 binoculars toward the Hyades
cluster (Caldwell 41), then in the eastern sky.
Suddenly she exclaimed that she had discovered
a comet and pointed a finger to a spot about 3½°
northeast of Aldebaran. There, to my surprise, I
saw a beautiful open cluster that had, for all
these years, escaped my gaze. Later, while
studying the Hyades (Caldwell 41) for this book,
I learned that the magnitude-6.4 glow of NGC
1467 could be seen with the naked eye from a
dark sky.
Through binoculars NGC 1467 is a lovely
cluster, appearing as a round ghostly glow with
an apparent size larger than that of the full Moon.
Undoubtedly, since I had lived most of my life in
the Boston area, light pollution must have
drowned out the cluster's pale glow, making it
11
Ghost Globular
N G C 5 8 9 7
T y G p l e o : Cl b u u l a s r t e r
C o L n i : b r a
RA: 15 h 17.4 m
Dec:-21° 01'
Mag: 8.5
Diam: 11'
Dist: 42,000 light-years
NGC 5897 is an unusually loosely structured
globular cluster that haunts the dim and unassuming
stars of Libra. Ernst Hartung calls it
"irregularly round" and "conspicuous." The
cluster can be seen on clear, moonless nights as a
easy to sweep past without notice. The Rev. T. W .
large amorphous glow nearly one-third the
Webb's description of the cluster in his Celestial
apparent size of Omega (ω) Centauri (Caldwell
Objects for Common Telescopes is rather perplexing,
80). Look for what appears to be the detached
for he writes: "Stars [of magnitudes] 8.5 to 10,
head of a flaring comet nearly midway between,
round wide pair" (I believe there should be a
and just south of, a line joining Delta (δ) Scorpii
comma between "round" and "wide pair"). The
and the wide double star Alpha
cluster is indeed quite round, and most of its 200
stars can be found within ½° of its core, where a
fine pair of 9th-magnitude stars dominates the
view. Other bright stars spiral out from the core
in crooked or disjointed arms. NGC 1647 is not
densely packed, however, and the view is best at
low power; in fact, Roger Clark suggests 20x for a
6-inch telescope and 27x for an 8-inch. In 1996
Michael Geffert and his colleagues visually
inspected NGC 1647 on a National Geographic
Society - Palomar Observatory Sky Survey print and
determined the position of this cluster's center;
they also determined that the Cepheid variable
SZ Tauri (whose apparent visual magnitude
ranges from 6.50 to 6.86 every 3.15 days) is
probably not a member of this cluster.
1,2 (α1,2 ) Librae
(Zubenelgenubi). At a glance in the 4-inch at 23x,
the cluster's oblate disk appears buffed and
featureless, as if its stars had been scrubbed away
with bleach. But with a little concentration you
can resolve the glow into a patchwork of
glittering hazes that lacks a strong central
condensation. The cluster's brightest stars shine
at magnitude 13.3, and they appear to form slight
needles of light that border minute "holes" at the
core. I call NGC 5897 the Ghost Globular because
it resembles a ghost image of the globular M55 in
Sagittarius. Actually NGC 5897 measures nearly
135 light-years across, making it 68 percent larger
than M55.
Adm. William Henry Smyth wrote extensively
about this "large compressed cluster of
minute stars," saying "it is faint and pale, but
owing to the fineness of the night, steadiness
Twenty Spectacular Non-Caldwell Objects 437