JUNE 2019 OBSERVING
Deep-Sky Wonders
56 JUNE 2019 • SKY & TELESCOPE
northwest gleams yellow. The luminous
star just east of center shines yellow,
and the next brightest to its east wears
a yellow-orange hue. Two stars smolder
orange: one in the southeastern edge,
and another of similar brightness 8′
south-southwest of the cluster’s center.
Besides the color, number, and diversity
of its stars, M25 holds another charm —
a cute little D of seven faint stars rests
at its heart.
Pointing the 130-mm scope to the
bright double star 5 Aquilae, the granu-
lar haze of Berkeley 79 shares the fi eld
of view and sports one faint star at 37×.
At 117× four dim stars emerge: three inBeyond the NGCs
Object Const. Mag(v) Size/Sep RA Dec.
Dolidze 27 Oph 6.3 25 ′ 16 h 36.5m –08° 56′
Collinder 316 Sco 3.4 105 ′ 16 h 55.5m –40° 49′
Trumpler 24 Sco 8.6 6 0′ 16 h 55.8m –40° 43′
Trumpler 26 Oph 9.5 7 ′ 17 h 28.5m –29° 30′
IC 4665 Oph 4.2 70 ′ 17 h 46.2m +05° 43′
Dolidze-Dzim 9 Her 6.2 34 ′ 18 h 08.8m +31° 32′
Messier 25 Sgr 4.6 30 ′ 18 h 31.8m –19° 07′
Berkeley 79 Aql — 10 ′ 18 h 45.0m –01° 09′
Stephenson 1 Lyr 3.8 40 ′ 18 h 54.5m +36° 54′
Angular sizes and separations are from recent catalogs. Visually, an object’s size is often smaller than
the cataloged value and varies according to the aperture and magnifi cation of the viewing instrument.
Right ascension and declination are for equinox 2000.0.a southward-pointing triangle and one
to its east. The northwestern triangle
star looks elongated at this power, but
going to 164× proves it to be a pair.
Some extremely faint stars also pop
into view. In the 10-inch at 68×, I see a
fairly large patch of mist sprinkled with
very faint stars, and 5 Aquilae exposes
three components in a little arc. At
187 × Berkeley 79 reluctantly surrenders
a central clump of 10 stars plus perhaps
20 corralled into a 10′ halo around it.
Berkeley clusters debuted in a two-part,
1962 paper by Arthur Setteducati and
Harold Weaver of the University of Cali-
fornia, Berkeley.We’ll fi nish our tour with Stephen-
son 1, the fetching splash of stars sur-
rounding Delta^2 (δ^2 ) Lyrae. This orange
star pins the cluster’s heart and offers a
pretty contrast with bluish-white Delta^1
to the west-northwest. About 30 to 40
mixed bright and faint stars embellish
a patch of sky at least ½° across. The
group was proposed as a possible cluster
in a 1959 paper by Charles Stephenson.
Although some of these clusters may
ultimately prove to be mere asterisms of
unrelated stars, stargazers usually judge
their worth by how interesting they
appear. I hope a few of them will catch
your attention and add bit of variety to
your observations of the sky we love.¢ Contributing Editor SUE FRENCH
would like to thank everyone for the kind
farewells, and she hopes to meet you
under the stars.A line drawn from
Omicron (ο) Sgr
to Xi^2 (ξ^2 ) Sgr in
the Teaspoon
asterism points
toward M25. Under
magnifi cation, the
open cluster reveals
an abundance of
colorful stars.pTop: The 6th-magnitude star 5 Aquilae
shares a fi eld of view with the somewhat dim
Berkeley 79, which resembles a meek pile of
caster sugar in the eyepiece. More aperture
and higher magnifi cation reveals individual
stars. Look for the central gathering of about a
dozen suns. Bottom: Many of us have probably
looked at Stephenson 1 without realizing it was
a star cluster. The orange Delta^2 Lyrae, which
shines at the cluster’s center, is surrounded by
30 to 40 stars as dim as 9th magnitude. Blue-
white Delta^1 is also a cluster member.M255 AqlBerkeley 79Sagittarius Stephenson 1ξ^2
οδ^2 Lyrδ^1 LyrM^25 SAGITTARIUS:^ S
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