The Caldwell Objects

suggest that our universe may be only 12 or 13
billion years old. NGC 5286 lies 28,000 light-years
from the galactic center and 36,000 light-years
from the Sun. In brightness, apparent size, and
distance, NGC 5286 resembles M68 in Hydra. The
cluster is moving toward us at 58 km per second,
a quarter of Omega Centauri's radial velocity.
Interestingly, if you were to reel NGC 5286 in to
Omega Centauri's distance, NGC 5286 would still
appear about 2.5 times smaller, and 10 times
fainter, than that great cluster.
James Dunlop discovered this cluster from
Australia with a 9-inch reflector. It is listed as the
388th object in his 1827 catalog. Of it he writes:
"A bright exceedingly well-defined rather
elliptical nebula, about 1' diameter, exceedingly
condensed almost to the very edge, and gradually
a little brighter to the centre. This is about 6'
north of Μ Centauri. — I have strong suspicion
that this is resolvable into stars."
From Hawaii I can see Μ Centauri with the
unaided eye but I could not resolve the cluster
next to it. I do not think it impossible to do so,
however, especially for someone who observes
from the Southern Hemisphere with younger
eyes than mine. The globular reveals itself with
the slightest of aperture. In 7x35 binoculars it
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looks like a tiny ghost image of Μ Centauri, a
dim puff of smoke wafting away from that
alluring flame-colored star. At 23x in the 4-inch,
the color contrast between the two objects is
remarkable. Μ Centauri looks strongly yellow
with a tinge of orange — like a dim Arcturus—
while the globular cluster glimmers with a very
pale ashen blue. Still, at this low magnification
little else can be seen; the cluster looks like a
circular wafer of uniform light, a breath spot on a
mirror. The late, great comet discoverer Jack
Bennett of South Africa included NGC 5286 as
the 64th entry in his list of objects that looked
cometlike through a 5-inch rich-field refractor.
Indeed, I have spotted NGC 5286's misleadingly
cometary form several times in my own comet
sweeps of the Centaurus area.
At 72x NGC 5286 appears as a moderately
condensed glow with stumps of starlight poking
out at the cardinal directions in a cruciform
shape. These are probably the "faint star points"
that Ernst Hartung glimpsed with his 4-inch
telescope. The cross lies on an elliptical bed of
fainter suns. Under a dedicated gaze, star
patterns seem to spiral out from the cluster's
condensed core, which appears very mottled or
patchy, as it is interspersed with dark veins. This
view is rather reminiscent of Dunlop's discovery
impression. And Dunlop's "strong suspicion" that
this cluster would resolve into stars was most
certainly justified. Although NGC 5286's
horizontal-branch magnitude is 16.5, the cluster's
brightest stars shine at a respectable magnitude
of 13.5, so partial resolution can be obtained in
good telescopes with apertures as small as 3
inches.
At high magnifications the cluster sports
some seven arms. Two of them — one to the
south and one to the east — form a counterclockwise
spiral. The other arms look more rigid.
Each is dappled by a few 13th- and 14th-
The Caldwell Objects 337