The Caldwell Objects

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69
NGC 6302
Bug Nebula
Type: Planetary
Nebula
Con: Scorpius
RA: 17 h 13 m 44.1 s
Dec: -37° 06' 14"
Mag: 9.6
Dim: 83" x 24"
Dist: ~5,200 light-
years
Disc: Edward
Emerson Barnard,
around 1883,
though he credits
James Dunlop, who may have included the nebula in
his 1827 catalog.
H ERSCHEL: None.
NGC 6302 is THE BRIGHTEST PLANETARY
nebula in Scorpius and one of the best of its kind
— the bipolar kind, that is — in the night sky. It
is easily located nearly 4° due west of Lambda (λ)
Scorpii (Shaula), the easternmost of the two
Stinger Stars in the Scorpion's tail. The nebula
now holds the honorable distinction of being the
first object imaged by the European Southern
Observatory's Very Large Telescope (actually it
was imaged by just one of the optical array's four
8.2-meter reflectors).
Edward Emerson Barnard found NGC 6302
around 1883, and he first described and drew its
curious form in a 1906 Astronomische Nachrichten
paper. Barnard, however, credited James Dunlop
with the nebula's discovery. It is unclear why, for
there is no object at the nebula's position in
Dunlop's 1827 catalog. I believe that Barnard —
tired, perhaps, from a night's observing — could
simply have failed to
274
GC: None.
NGC: Pretty bright, extended preceding-following [west to
east], planetary nebula.
realize that Dunlop listed his objects by South
Polar Distance (the angular distance from the
South Celestial Pole). By sheer coincidence,
Dunlop's 366th listing has a South Polar Distance
similar to the Bug Nebula's declination. What's
more, that object's opening description — a
"pretty large nebula, extended in the parallel of
the equator" — fits the Bug. Dunlop 366,
however, is actually NGC 6397 (Caldwell 86), a
globular cluster in Ara. (It is conceivable that
Barnard observed Dunlop 567. Described by
Dunlop as a "very faint, small, ill-defined nebula,
with a small star in it," this object has coordinates
that, when properly precessed, lie a mere 8' from
the Bug. However, the Bug is both larger and
brighter than Dunlop's description seems to
imply. Is Dunlop 567 the Bug? Your guess is as
good as mine.)
Now consider that neither William nor John
Herschel saw the Bug. This seems as-
Deep-Sky Companions: The Caldwell Objects