Sky and Telescope - July 2017 - 34
by Steve Gottlieb
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p SPHERICAL SYMMETRY This image of Abell 39 was
taken with the WIYN Observatory's 35-meter telescope at
Kitt Peak National Observatory through a blue-green filter
that isolated the light emitted by doubly ionized oxygen at
the wavelength of 500.7 nanometers.
J U L Y 2 0 1 7 * SK Y & TELESCOPE
While a Caltech graduate student in the early 1950's, George O. Abell
was given a research assistantship to work on the renowned National
Geographic Society-Palomar Observatory Sky Survey (POSS), taking blueand red-sensitive plates with the 48-inch Schmidt telescope. Before
the photographic plates were sent down to Caltech for approval, Abell
made a preliminary check and quickly jotted down notes on new low
surface brightness planetary nebulae and globular clusters.
In 1955 he published a list of 73 "Abell" planetaries. He followed
this list up with a comprehensive study titled "Properties of Some Old
Planetary Nebulae," which he published in the Astrophysical Journal in
1966. Abell's ﬁnal catalog included 86 objects north of -35° declination. A few turned out to be plate ﬂaws and imposters (galaxies and
nebulae). Another four had been previously discovered visually and
already carried NGC or IC designations, but hadn't been recognized
as planetary nebulae.
G EORG E JACOBY / WIY N / NOAO / NSF