Sky & Telescope - September 2023 - 48

SEPTEMBER 2023 OBSERVING
Celestial Calendar by Bob King
Hyperactive Comet Hartley
An icy visitor pays a return visit this month to delight telescope users.
P
eriodic comets are a joy. We get to
tag along and watch them grow
from fuzzy midges to tailed wonders
and back again as they make their way
sunward and then return to the deeps.
Whenever a favorite fuzzball recedes
from the Sun and fades from view, I
find it hard to say goodbye. That's why
I look forward to the return of Comet
103P/Hartley. This periodic comet last
reached perihelion in 2017, when it was
poorly placed and faint. The most recent
favorable apparition occurred more
than a decade ago, in the fall-winter of
2010-11, when it reached 5th magnitude.
Clearly, we're overdue.
Hartley arrives at perihelion on
October 12th, making September ideal
for watching it brighten from around
9th to 8th magnitude. From a dark
sky, a 6-inch telescope should easily
show Hartley's fuzzy coma, bright false
nucleus, and perhaps hints of a westward-pointing
tail.
Sliding eastward across central
Perseus in early September, 103/P puts
on a good appearance in the northeastern
sky starting at around 10:30
p.m. local daylight time. It fights the
waning gibbous Moon during the first
week of September but will be in a dark
sky afterwards, until the Moon returns
around September 27th. As Hartley
creeps eastward into Auriga, its evening
altitude declines. That's when your best
views will come after midnight or just
before dawn, when the comet culminates
nearly overhead for skywatchers
NGC 1545
µ
π
NGC 2281
β
ε
2
1
q
3
4
5
6
7
8
29
Oct 1
M37
ι
κ
6h 30m
6h 00m
5h 30m
48 SEPTEMBER 2023 * SKY & TELESCOPE
NGC 1893
β
5h 00m
4h 30m
PERSEUS
ζ
4h 00m
Cr 62
ν
θ
25
27
M36
IC 348
ο
TAURUS
3h 30m
+30°
M38
23
NGC
1857
21
NGC 1778
ξ
15
η
19
ζ 17
ε
NGC 1342
ρ
AURIGA α
Capella
5
NGC 1664
7
NGC 1582
13
9
11
ν
Algol
β
+40°
NGC 1528
λ
δ
at mid-northern latitudes.
Hartley's circuit takes it through a
rich region of the northern Milky Way
and includes several must-see, deep-sky
flybys:
* within ½° of the bright open cluster
M34 in Perseus on the night of
August 31-September 1
* 6′ north of the 11.4-magnitude
galaxy NGC 1186 (also in Perseus)
on September 3rd at around 2:30 UT
(10:30 p.m. EDT)
* 30′ southwest of the 7th-magnitude
open cluster NGC 1857 (Auriga), on
the morning of September 20th
* 2.1° north of the open cluster M38
(Auriga) on September 21-22
* 3° north of the open cluster M37
(Auriga) on September 25-26.
α
ι
σ
ψ
κ
3
Sept 1
M34
θ
Path of Comet
103P/Hartley
Star magnitudes

Sky & Telescope - September 2023

Table of Contents for the Digital Edition of Sky & Telescope - September 2023

Contents
Sky & Telescope - September 2023 - Cover1
Sky & Telescope - September 2023 - Cover2
Sky & Telescope - September 2023 - 1
Sky & Telescope - September 2023 - Contents
Sky & Telescope - September 2023 - 3
Sky & Telescope - September 2023 - 4
Sky & Telescope - September 2023 - 5
Sky & Telescope - September 2023 - 6
Sky & Telescope - September 2023 - 7
Sky & Telescope - September 2023 - 8
Sky & Telescope - September 2023 - 9
Sky & Telescope - September 2023 - 10
Sky & Telescope - September 2023 - 11
Sky & Telescope - September 2023 - 12
Sky & Telescope - September 2023 - 13
Sky & Telescope - September 2023 - 14
Sky & Telescope - September 2023 - 15
Sky & Telescope - September 2023 - 16
Sky & Telescope - September 2023 - 17
Sky & Telescope - September 2023 - 18
Sky & Telescope - September 2023 - 19
Sky & Telescope - September 2023 - 20
Sky & Telescope - September 2023 - 21
Sky & Telescope - September 2023 - 22
Sky & Telescope - September 2023 - 23
Sky & Telescope - September 2023 - 24
Sky & Telescope - September 2023 - 25
Sky & Telescope - September 2023 - 26
Sky & Telescope - September 2023 - 27
Sky & Telescope - September 2023 - 28
Sky & Telescope - September 2023 - 29
Sky & Telescope - September 2023 - 30
Sky & Telescope - September 2023 - 31
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Sky & Telescope - September 2023 - 33
Sky & Telescope - September 2023 - 34
Sky & Telescope - September 2023 - 35
Sky & Telescope - September 2023 - 36
Sky & Telescope - September 2023 - 37
Sky & Telescope - September 2023 - 38
Sky & Telescope - September 2023 - 39
Sky & Telescope - September 2023 - 40
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Sky & Telescope - September 2023 - 42
Sky & Telescope - September 2023 - 43
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Sky & Telescope - September 2023 - 45
Sky & Telescope - September 2023 - 46
Sky & Telescope - September 2023 - 47
Sky & Telescope - September 2023 - 48
Sky & Telescope - September 2023 - 49
Sky & Telescope - September 2023 - 50
Sky & Telescope - September 2023 - 51
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Sky & Telescope - September 2023 - 53
Sky & Telescope - September 2023 - 54
Sky & Telescope - September 2023 - 55
Sky & Telescope - September 2023 - 56
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Sky & Telescope - September 2023 - 63
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Sky & Telescope - September 2023 - 67
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Sky & Telescope - September 2023 - 69
Sky & Telescope - September 2023 - 70
Sky & Telescope - September 2023 - 71
Sky & Telescope - September 2023 - 72
Sky & Telescope - September 2023 - 73
Sky & Telescope - September 2023 - 74
Sky & Telescope - September 2023 - 75
Sky & Telescope - September 2023 - 76
Sky & Telescope - September 2023 - 77
Sky & Telescope - September 2023 - 78
Sky & Telescope - September 2023 - 79
Sky & Telescope - September 2023 - 80
Sky & Telescope - September 2023 - 81
Sky & Telescope - September 2023 - 82
Sky & Telescope - September 2023 - 83
Sky & Telescope - September 2023 - 84
Sky & Telescope - September 2023 - Cover3
Sky & Telescope - September 2023 - Cover4
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