Sky & Telescope - July 2022 - 56

MASIL IMAGING TEAM
JULY 2022 OBSERVING
Suburban Stargazer
BACK OF THE CLASS Harvard 20 is a
seldom-observed open cluster containing
roughly 100 members. The distance to H20 is
about 5,700 light-years - much closer than
M71, yet far less conspicuous.
M71
open cluster cataloged as Harvard 20
sits a mere ½° south-southwest of M71.
Obscure or not, I figured H20 wouldn't
be difficult to find because it's accompanied
by two relatively isolated stars:
9.2-magnitude HD 350800 and, 2.7′
northeast, yellowy, 8.9-magnitude HD
350801. The latter actually overlays the
northern edge of the cluster.
Astronomers think HD 350801
HD 350801
H20
HD 350800
belongs to H20. Maybe so, but the
other cluster members are significantly
fainter. If we ignore the HD beacon,
H20 is a sparse scatter of several dozen
11th- to 13th-magnitude stars 6′ to 9′
across (depending on the source consulted).
Barely detached from its Milky
Way surroundings, the cluster appears
dimmer than its total visual magnitude
of 7.7 would suggest. In short, H20 isn't
much of a target for backyard scopes.
I went after it anyway, but to ensure
success I turned to a third scope - my
10-inch f/6 Dobsonian.
It was the right choice. Picking off
Sagitta Treasures
Object
Type
Σ2585
ΣI48
Σ2637AB
Σ2637AC
M71
H20
Double star
Double star
Double star
Double star
Globular cluster
Open cluster
Mag(v)
5.0, 9.0
7.1, 7.3
6.6, 8.9
6.6, 7.5
8.4
7.7
Size/Sep
8.3″
41.7″
11.6″
91.9″
7.2′
~6′
RA
19h 49.0m
19h 53.4m
20h 09.9m
20h 09.9m
19h 53.8m
19h 53.3m
Dec.
+19° 09′
+20° 20′
+20° 55′
+20° 55′
+18° 47′
+18° 21′
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 magnification of the viewing instrument.
Right ascension and declination are for equinox 2000.0.
the 9th-magnitude companion stars
was a snap for the 10-inch at 48× and
doubling to 96× produced a hazy suggestion
of a cluster surrounding HD
350801. Cranked up to 169×, the scope
pulled in a coarse scatter of a dozen or
more dim stars. The roughly triangular
assemblage aimed eastward, away from
the HD leader. The cluster's southern
edge was sharply defined by a string of
four faint stars - a 12th magnitude pair
westward and a wider, 11th-magnitude
pair eastward. Curiously, something
fuzzy at the threshold of vision lay in
between the eastern set. Careful viewing
at 218× confirmed my suspicion: It
was a teensy double.
Harvard 20 isn't special, but it was a
satisfying catch - especially from town.
I hope you give it and the other Arrow
objects the ol' college try.
¢ Contributing Editor KEN HEWITTWHITE
has had Sagitta in his quiver for
more than 50 years.
56 JULY 2022 * SKY & TELESCOPE

Sky & Telescope - July 2022

Table of Contents for the Digital Edition of Sky & Telescope - July 2022

Contents
Sky & Telescope - July 2022 - Cover1
Sky & Telescope - July 2022 - Cover2
Sky & Telescope - July 2022 - 1
Sky & Telescope - July 2022 - Contents
Sky & Telescope - July 2022 - 3
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