The Caldwell Objects

70 & 72
one roughly 8.5-magnitude star, to its east. I
really needed averted vision to make out the
spindle in binoculars. With a semidirect gaze the
galaxy appears to have a slightly elliptical center
with a hint of tapered edges.
At 23x the 4-inch immediately reveals NGC
55's splendor. At a glance the galaxy looks like a
beautiful comet, with a graceful dust tail
extending to the east-southeast and a small
antitail to the west-northwest. The view becomes
three-dimensional if you imagine a comet racing
toward you at a slightly inclined angle. Make
sure you spend time with this galaxy. The longer
you look at it, the more you should see.
Gradually, the nuclear region should begin to
appear more irregular, and faint stars should
begin to appear along its length. I like to imagine
the galaxy as a squashed comet — like the one
Carolyn Shoemaker discovered on photographic
plates taken by her husband Eugene and by
David Levy. Carolyn called that broken-up
comet a "string of pearls" after seeing an image of
it taken with the Spacewatch telescope. (That
comet, Comet Shoemaker-Levy 9, ultimately
smashed into Jupiter.) As I see it, NGC 55 is an
extragalactic String of Pearls. Curiously, under
averted vision its eastern segment (IC 1537)
seems to pulsate with dim, glittering lights. The
effect is most dramatic when I look toward the
nucleus at 23x but keep my attention on IC 1537.
It's like a flashing signal reminding me to use
higher magnification.
At medium magnification NGC 55 is stunning.
Ribbons of dark material lace its entire
nuclear region; the "comet" has been snared in a
black net. The scene recalls M82, the fabulous
starburst galaxy in Ursa Major. Concentrate on
NGC 55's core with averted vision and it should
scintillate with faint fuzzes and stars. One phenomenal
rift slices through the eastern end of the
central bulge before it curls around the
282
dense core like warped metal. It's as if tiny
explosions have blown apart the hull of this
extragalactic traveler, which is tipping to the
northwest and sinking into a black sea; any
turbulence in our atmosphere will cause the
dimmest parts to ripple as if against this "ship's"
hull. The galaxy's fainter eastern segment is also
highly fractured and dappled with clusters of
faint stars. This ethereal beauty recalls the words
quoted by Strepsiades in Aristophanes's The
Clouds: "the impetuous tempests, which float
through the heavens... with aerial wings, loaded
with mists."
Despite NGC 55's modest overall surface
brightness, its bright nuclear region takes high
magnification well. In fact, I think the nuclear
region looks best at high power. Here the dark
rifts can be seen weaving through the superimposed
stars and knots like streams covered with
black ice flowing through banks of snow. The
sight must be glorious in larger telescopes.
Through her 17½-inch f/4.5 reflector Barbara
Wilson saw NGC 55 as a "long streak narrower at
one end with mottling in the central nuclear
region. The galaxy extends beyond the field of
the eyepiece at 95x. Incredible."
NGC 55 is without a doubt one of the most
spectacular galaxies available to amateurs. But
observers at midnorthern latitudes have it tough,
since the galaxy is so low in their skies,
Deep-Sky Companions: The Caldwell Objects