The Caldwell Objects

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7x35 binoculars and tried to see it in those. With
averted vision and a little time, the dust lane
indeed was apparent in my binoculars.
At 23x in the 4-inch NGC 5128 looks like a
cell undergoing mitosis. Both halves of the galaxy
are immediately visible, as is the dust lane. The
galaxy's brightest section is oriented eastsoutheast
to west-northwest, and the lane runs
fully across its face in that direction. At low light
levels, however, the galaxy's long axis extends
from northeast to southwest. But at low power,
this all blends into a slightly elliptical fog that is
perhaps only one-third as large as the galaxy's
published angular size. The galaxy's elliptical
envelope is so dim that high magnification only
diminishes its appearance. So in the 4-inch at 72x
and higher powers, the galaxy looks as if it is
oriented from east-southeast to west-northwest.
With careful scrutiny the dust lane appears wavy
and widens on the eastern end. The galaxy's
southern half appears brighter than its northern
half, and a roughly 9th-magnitude star
punctuates the southeastern rim of the outer
envelope. (Again, this is visible only at low
power.)
At higher power the galaxy is gracefully
defined, the dust lane looking like a silken veil.
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The reason the southern half looks brighter than
the northern half also becomes clear — two
prominent foreground stars are superposed upon
it. One, shining at roughly 12th magnitude, lies
dead center, while a dimmer (magnitude-13.5)
star lies on the south side of the dust lane to the
west. Together the 9th-, 12th-, and 13.5magnitude
stars form an arc of diminishing
brightness. Two concentrations of light (or even
dimmer suns) lie to the east and west of the 12thmagnitude
star. Supernova hunters should take
note of these stars, because they do not appear in
many photographs, which tend to burn out the
galaxy's bright hemispheres. These stars have
been mistaken for supernovae in the past. The
dust lane's entire northern lip appears bright.
Interestingly, this is where the Hubble Space
Telescope imaged many of the galaxy's hot
young star clusters. The galaxy's uniformly bright
northern hemisphere looks something like a
German World War II helmet. The dust lane
widens to the east, as noted above, and fades into
a diminishing sea of delicate vapors, like a
slightly submerged walkway. In a more comical
vein, Barbara Wilson likened the overall view to
that of a hamburger. Through her 13.1-inch
reflector, she saw the dust lane as mottled.
If you own a medium-size or large telescope,
try swinging it a little more than 1° to the southwest,
where a gaggle of six dim galaxies lies in a
field only ½° wide. These are NGC 5082, NGC
5086, NGC 5090, NGC 5090A, NGC 5090B, and
NGC 5091. Most of them lie immediately
southwest of a 7th-magnitude star. Small-telescope
users should at least try for the brightest of
these, NGC 5090, which shines at magnitude 11.6
from a distance of approximately 150
million light-years. Good luck.
Deep-Sky Companions; The Caldwell Objects