The Caldwell Objects

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Light Blue Snowbal
NGC 7662
Type: Planetary Nebula
Con: Andromeda
RA: 23 h 25 m 53.9 s
Dec: +42° 32' 06"
Mag: 8.3
Dim: 32" x 28"
Dist: 3,200 light-years
Disc: William Herschel, 1784
W. H ERSCHEL: [Observed 6 October 1784] Bright, round, a
planetary [with a] pretty well defined disk. 15" diameter with a
7 feet reflector. (Η IV-18)
GC: Planetary, very bright, pretty small in angular size, round,
blue.
NGC 7662 is A BRIGHT DOUBLE- SHELLED
planetary nebula with a mysterious central star.
The nebula's core is so condensed that city
observers with 7x35 binoculars have spied it as a
"star" shining just 25' southwest of 5 th-magnitude
13 Andromedae, which lies about 15° north of the
Great Square of Pegasus. A magnitude-7.9 star
lies just to the planetary's east, and the two form
an obvious pair. Through the Genesis NGC 7662
remains stellar at 23x, but with the magnification
increased to 72χ a pale aquamarine nebula
suddenly swells to prominence, displaying a
sharp core, a dense inner ring, and a diffuse outer
envelope. At 189x the sharp core reveals itself not
as a central star but as two bright arcs of nebulosity,
one to the northeast, the other to the
southwest. These surround a small cavity of dim
light marking the center of the annulus. A diffuse
aquamarine shell surrounds this bright inner ring
and is elongated in the same direc-
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Ν GC: A magnificent planetary or annular nebula, very bright,
pretty small in angular size, round, blue, variable nucleus.
tion. "This planetary was observed 16 times by
William and lohn Herschel," notes Barbara
Wilson. "They must have loved looking at it!" In
the General Catalogue there is the following note:
"According to Mr. [William] Lassell this superb
'planetary nebula' is bi-annular, consisting of a
nucleus and two oval rings" Note, too, that John
Herschel was the first of many observers to
notice a blue tint to NGC 7662.
NGC 7662 has long been known as the Blue
Snowball Nebula. Veteran Sky & Telescope editor
Dennis di Cicco has credited Leland Copeland
with originating this nickname. "Looking like a
light blue snowball" is how Copeland described
NGC 7662 in the magazine's February 1960 issue.
"The key here is that the words 'blue snowball'
don't have quotation marks and the first letter in
each word is not capitalized," di Cicco stresses;
"Copeland was just describing the object in his
own words." Interestingly, Copeland's important
Deep-Sky Companions: The Caldwell Objects