Sky & Telescope - February 2024 - 48

CHART: BEATRIZ INGLESSIS / S&T; STAR MAGNITUDES: AAVSO
FEBRUARY 2024 OBSERVING
Celestial Calendar by Bob King
10h 05m
10h 00m
9h 55m
9h 50m
9h 45m
+13°
ν
UGC 5470
α
Regulus
LEO
76
83
78
+10°
ο
X
69
64
R
100
98
110
88
70
+11°
92
87
109 91
+12°
84
57
+9°
Star magnitudes
4 5 6 7 8 9 10 11
A Pair of Leo Variables
Meet R Leonis and its next-door neighbor, X Leonis.
I
f you haven't observed Leo's brightest
Mira-type variable star, stop by for a
peek at R Leonis this month. A ruddy
nugget tucked into a binocular asterism
shaped like a bent fishing rod, R Leonis
is located about 5° west of Regulus,
Alpha (α) Leonis. As the variable
expands and contracts over a period of
312 days, its visual brightness varies on
average from about magnitude 5.8 to
10.0. During its contraction phase, the
red giant heats up and brightens. When
expanding, its surface cools and dims.
The star was previously at minimum
light last autumn. Now awakened from
its slumber, it's on the rise. At the start
48 FEBRUARY 2024 * SKY & TELESCOPE
of February, R Leonis should be visible
in a 60-mm telescope and possibly
50-mm binoculars at about magnitude
8.5, then brighten to 7 or better by Leap
Day. Maximum light should occur in
late March or early April. If you observe
the star once a week, you'll notice its
increasing brilliance soon enough. Its
vivid red-orange color stands in marked
contrast to other stars in the telescopic
field of view, making it a cinch to spot.
When R Leonis exceeds 8th magnitude,
I break out the binoculars to
estimate its brightness. You can use the
chart presented above or make your own
with the help of the American AssociapUse
this chart to locate the variable stars
R and X Leonis, roughly 5° west of Regulus.
Comparison star magnitudes are given with
their decimal points omitted (e.g., a magnitude
11.0 star is labeled " 110 " ).
tion of Variable Star Observers (AAVSO).
Go to aavso.org, type in " R Leo " in the
Pick a Star box and select Create a finder
chart. You also have the option of creating
charts at different scales - larger
fields that contain the brightest relevant
stars and narrower views to use when
the star fades. Note that magnitudes
shown in our map above have the decimal
points omitted.
R Leonis became an early favorite
when I first joined the AAVSO in 1982.
To be honest, finding my first variable
was anything but easy. It's one thing
to hunt for an extended object like
a globular cluster and quite another

http://www.aavso.org

Sky & Telescope - February 2024

Table of Contents for the Digital Edition of Sky & Telescope - February 2024

Contents
Sky & Telescope - February 2024 - Cover1
Sky & Telescope - February 2024 - Cover2
Sky & Telescope - February 2024 - 1
Sky & Telescope - February 2024 - Contents
Sky & Telescope - February 2024 - 3
Sky & Telescope - February 2024 - 4
Sky & Telescope - February 2024 - 5
Sky & Telescope - February 2024 - 6
Sky & Telescope - February 2024 - 7
Sky & Telescope - February 2024 - 8
Sky & Telescope - February 2024 - 9
Sky & Telescope - February 2024 - 10
Sky & Telescope - February 2024 - 11
Sky & Telescope - February 2024 - 12
Sky & Telescope - February 2024 - 13
Sky & Telescope - February 2024 - 14
Sky & Telescope - February 2024 - 15
Sky & Telescope - February 2024 - 16
Sky & Telescope - February 2024 - 17
Sky & Telescope - February 2024 - 18
Sky & Telescope - February 2024 - 19
Sky & Telescope - February 2024 - 20
Sky & Telescope - February 2024 - 21
Sky & Telescope - February 2024 - 22
Sky & Telescope - February 2024 - 23
Sky & Telescope - February 2024 - 24
Sky & Telescope - February 2024 - 25
Sky & Telescope - February 2024 - 26
Sky & Telescope - February 2024 - 27
Sky & Telescope - February 2024 - 28
Sky & Telescope - February 2024 - 29
Sky & Telescope - February 2024 - 30
Sky & Telescope - February 2024 - 31
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Sky & Telescope - February 2024 - 33
Sky & Telescope - February 2024 - 34
Sky & Telescope - February 2024 - 35
Sky & Telescope - February 2024 - 36
Sky & Telescope - February 2024 - 37
Sky & Telescope - February 2024 - 38
Sky & Telescope - February 2024 - 39
Sky & Telescope - February 2024 - 40
Sky & Telescope - February 2024 - 41
Sky & Telescope - February 2024 - 42
Sky & Telescope - February 2024 - 43
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Sky & Telescope - February 2024 - 45
Sky & Telescope - February 2024 - 46
Sky & Telescope - February 2024 - 47
Sky & Telescope - February 2024 - 48
Sky & Telescope - February 2024 - 49
Sky & Telescope - February 2024 - 50
Sky & Telescope - February 2024 - 51
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Sky & Telescope - February 2024 - 55
Sky & Telescope - February 2024 - 56
Sky & Telescope - February 2024 - 57
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Sky & Telescope - February 2024 - 60
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Sky & Telescope - February 2024 - 62
Sky & Telescope - February 2024 - 63
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Sky & Telescope - February 2024 - 65
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Sky & Telescope - February 2024 - 67
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Sky & Telescope - February 2024 - 69
Sky & Telescope - February 2024 - 70
Sky & Telescope - February 2024 - 71
Sky & Telescope - February 2024 - 72
Sky & Telescope - February 2024 - 73
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Sky & Telescope - February 2024 - 81
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Sky & Telescope - February 2024 - 83
Sky & Telescope - February 2024 - 84
Sky & Telescope - February 2024 - Cover3
Sky & Telescope - February 2024 - Cover4
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