The Caldwell Objects

pair of tweezers. A fairly bright star or clump
punctuates the galaxy's northeastern end, and a
slightly fainter, though prominent, clump lies
due east of the bright hub on the southeastern
rim. The galaxy appears to bulge toward the
southeast, making the northeastern section of the
disk appear narrow. But photographs show this
to be an illusion created by a dense ribbon of dust
blocking the light. A series of clumps in an arc
bowing to the southwest surrounds the nuclear
region on the southwestern side, giving the
nuclear region a slightly parabolic look. The
northern prong on the southwestern limb of the
disk appears kinked.
The view at high power is quite interesting.
The galaxy no longer appears uniformly bright
along its full extent. Rather, its southwestern end
is dramatically more obvious. Interestingly, this
is exactly what the galaxy's discoverer, James
Dunlop, observed:
A beautiful long nebula, about 10' long, and 2'
broad, forming an angle with the meridian,
about 30° south preceding and north following
[from southwest to northeast!; the brightest and
broadest part is rather nearer the south
preceding [southwestern] extremity than the
centre, and it gradually diminishes in breadth
and brightness towards the extremities, but the
breadth is much better defined than the length.
A small star near the north, and a smaller star
near the south extremity, but neither of them is
involved in the nebula. I have strong suspicions
that this nebula is resolvable into stars, with
very slight compression towards the centre. I
have no doubt but it is resolvable. I can see the
stars, they are merely points.
83
You can sense the enthusiasm of the moment in
that passage. Clearly Dunlop was picking out the
clumps of starlight shining through the long dust
lanes and patches that run the length of the
galaxy, as well as a number of foreground stars
in that rich section of the Milky Way. In his 12inch
telescope, Ernst Hartung found the
northwestern side slightly convex and fairly
uniform in brightness except toward the fading
ends. And in her 13.1-inch reflector at 105x
Barbara Wilson saw NGC 4945 as a "long wispy
streak of light that filled the eyepiece [and] looks
like a flying saucer."
Overall NGC 4945 reminds me of M82, what
with the interplay between its dark lanes and its
illuminated portions. The real challenge I found
at high power was to resolve the dark notch or
"eyelash" between the eastern clump and the
nublike core. Much of the dark material in this
galaxy can be inferred visually from the
patchiness of the luminous sections. Take your
time and be patient. I would suggest spending
several nights on this galaxy. Keep good records,
make plenty of drawings, and your observations
should yield more and more detail.
Before moving on, try for NGC 4976, a l0thmagnitude
spiral galaxy about 30' due east of
NGC 4945. It's a nice compact (5.4' x 3.3') object
that can be mistaken for a star. A star of roughly
magnitude 8.5 abuts it to the east.
The Caldwell Objects 335