The Caldwell Objects

longed look, the object displays a very bright
center (the 10th-magnitude central star) surrounded
by a tight, tiny halo with an irregular or
dappled texture. Depending on how you hold
your head or move your eye, spectral glows
brighten and fade around the "halo." At high
power NGC 3132 becomes immediately
intriguing. My first view was of a ring of knots
with some skewed outer envelopes surrounding
a bright central star. All these features appear to
be at the threshold of visibility in the 4-inch. A
knot will pop into view, then vanish quickly, just
as another curious haze or enhancement
gradually materializes, then dissipates. In a
sense, this illusory action reminded me of the
"rotating" beads of light in M57. Most curious,
however, is the appearance of a double shell. The
outer shell seems slightly skewed
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with respect to the inner ellipse. I can also see
what appears to be a tiny nebulous hook on the
northwestern side of the ellipse, where Christian
Luginbuhl and Brian Skiff, looking through a 12inch
reflector, note that the "otherwise ring-like
structure is broken." A faint star, perhaps 13th
magnitude, borders the ring to the southwest.
John Herschel observed this nebula several
times with his 18¼-inch reflector. On one night
he saw the nebula as "velvety, or like infinitely
fine dust." Ernst Hartung saw no color in NGC
3132 and called it a "bright white annular
planetary nebula . . . without any of the bluish
tint usual with planetary nebulae." Steve Coe,
observing NGC 3132 with a 13-inch f/5.6
instrument, recorded a hue that was "either grey
or light green on every occasion I have observed
it." Like Hartung, I saw no color.
The Caldwell Objects 295