Sky and Telescope - July 2017 - 36
p BLUE BOX For this 25′ × 25′ field of view, Don Goldman applied O III, H-alpha, and S II filters to bring out the structure of Abell 65. RGB data were
also gathered for star colors for a total exposure time of 13 hours.
NGC 6742. You'll ﬁnd this compact 13.4-magnitude planetary in southern Draco, about 1.6° north-northwest of 5thmagnitude 16 Lyrae.
With a ﬁlter-equipped low-power eyepiece, Abell 50
showed as a bright 30″ disc, a mere 3′ northeast of an
8.8-magnitude star. Upping the power to 325× exposed subtle
details - the planetary was a bit distended east-west and
seemed weakly annular due to an augmented fringe. A 15thmagnitude star lies just off the north side and occasionally a
16th-magnitude star emerged along the west edge.
Abell 55 is set in a wonderfully rich section of the Milky
Way, 2.7° north-northeast of 3.4-magnitude Lambda (λ)
Aquilae. In the same region you'll also ﬁnd the brighter planetaries NGC 6741, NGC 6772, and NGC 6778. Abell reported
a discouragingly faint photographic magnitude of 15.4, but
don't be deterred by that. Visually, Abell 55 appears about two
magnitudes brighter, and that's typical for his planetaries.
Although I vaguely detected Abell 55 without a ﬁlter, I
noticed a signiﬁcant contrast gain with both O III and narrowband ﬁlters. At 160× I could hold it continuously as a fairly
uniform oval, extending 45″ × 35″ from northeast to southwest and fading a bit at the periphery. Unﬁltered, the ﬁeld was
chock-full of dim stars with several tightly hugging the edge.
J U L Y 2 0 1 7 * SK Y & TELESCOPE
Abell 65 is an unusually elongated planetary in eastern
Sagittarius, just following a string of four 10th-magnitude
stars. Based on its diffuse elliptical appearance, Abell 65 was
mistaken for a remote galaxy and appears in several galaxy
catalogs, so don't be confused if you ﬁnd it identiﬁed as PGC
63654 in some amateur sky-plotting software.
Using 115×, I found a moderately bright boxy oval, extending 1.8′ × 0.8′ wide. A 13th-magnitude star is pinned to the
southeast end, and at high power the 15th-magnitude central
star popped into view.
A study published in the Monthly Notices of the Royal Astronomical Society in 2013 characterized Abell 65 as a unique
double-shelled planetary with a binary central star. The shells
have a bipolar, peanut-shaped structure resulting from two
ejections of fast stellar wind perpendicular to the orbital
plane of the binary star.
Abell 70 is one of my favorite summer objects because of a
remarkable juxtaposition - a background radio galaxy shines
through the halo! At an approximate distance of 250 million
light-years, PGC 187663 is over 10,000 times as distant as the
planetary. Since the nucleus of the galaxy is visible directly
through the nebula's rim, Abell 70 has been dubbed the "Diamond Ring" planetary. You'll ﬁnd this planetary in eastern