Sky & Telescope - July 2023 - 43

α
VULPECULA
M27
5
γ
δ
M71
α
β
AQUILA
SAGITTA
Binocular Highlight by Mathew Wedel
ε
My Old Enemy
O
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M13
ES
ζ
ur target this month is M71, an 8.4-magnitude
globular cluster in Sagitta, the Arrow, hanging
halfway between Delta (δ) and Gamma (γ) Sagittae.
More than any other celestial object, M71 taught
me how to observe. Early on, I struggled to find the
cluster at all, despite using a 6-inch reflector. Now I
check in on it regularly - and more often than not,
I'm only using binoculars. So, what changed?
In the old days I'd haul out the scope, paying
β
M12
C H U S
ν β
δ
σ
α
M4
τ
ε
µ
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7h
g Sou
WHEN TO
USE THE MAP
Late May 2 a.m.*
Early June 1 a.m.*
Late June Midnight*
Early July 11 p.m.*
Late July Nightfall
*Daylight-saving time
π
minimal attention to local conditions or where things
were situated in the sky, then start running up the
magnification. That was exactly the wrong strategy
for M71. The cluster is so loosely aggregated that for
a long time astronomers suspected it to be a dense
open cluster rather than a globular. To make matters
worse, M71 sits in a dense stretch of the Milky Way.
High magnification restricts the field of view so much
that the cluster starts to blend into the rich galactic
background, especially in poor skies.
Gradually I learned to approach M71 as a hunter:
humbly and deliberately. Now, I wait for clear skies
and for the cluster to culminate - so it's as high in the
sky as possible. I cultivate my dark adaptation and
avoid local light pollution. And I use clean, clear optics
at low power. Even then, M71 is still a challenge for
me in 7×50 binoculars. With 10×50s it's more straightforward,
though it remains a faint ball of fluff. Bigger
binos will reel it in easily most nights, pulling down
starlight that has been traveling for 13,000 years,
since the end of the most recent Ice Age.
I visit M71 frequently, not just to see how it's doing,
but also to see how I'm doing as an observer. It's the
stone that keeps me sharp.
¢ MATT WEDEL's biggest observing debacle was
focusing on what he thought was Saturn . . . on its
final approach to LAX.
sk yand tele scope .o r g * JULY 2023 43
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June 29
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M82
Moon
June 25
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Sky & Telescope - July 2023

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