BBC Sky at Night - UK (2021-08)

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1. 3, 4 and 5 Aquarii
   4 and 5 Aquarii comprise a very
   easy double star, at mag. +5.5 and
   mag. +6.4 respectively, separated by 13
   arcminutes. This is a line-of-sight pairing,
   not a true binary star. A degree or so
   to the northwest you will see a brighter
   orange star. This is the slightly variable
   (mag. +4.4 to +4.5) 3 Aquarii. If you enjoy
   looking at coloured stars, scan the region
   5° northwest of 3 Aquarii.  SEEN IT


2. M2
   The globular cluster M2 forms a
   right-angled triangle with Sadalsuud
   (Beta (`) Aquarii) to the south and
   Sadalmelik (Alpha (_) Aquarii) to the east.
   It stands out, even in small binoculars, in
   an otherwise sparse region of sky, looking
   exactly as Charles Messier described it:
   “a nebula without stars”. Try averted vision
   by directing your gaze to 24 Aquarii, 1°
   east of the cluster, and you might notice
   that it appears slightly oval.  SEEN IT
   3. M15
   Our second globular cluster, M15,
   is another easy target. Find it by
   extending a line from Biham (Theta (e)
   Pegasi) to Enif (Epsilon (¡) Pegasi) another
   4° northwest. It appears rounder and
   brighter than M2, but do not expect to
   see it even half as wide (18 arcminutes) as
   planetarium programs suggest. Most of
   its stars are densely concentrated into
   the core so only the central third of it is
   visible in 50mm binoculars.  SEEN IT
   4. Eta Aquilae
   In 1784, the York-based astronomer
   Edward Piggott announced the
   discovery of a star that varied in brightness:
   Eta (d) Aquilae. This is one of the brightest
   Cepheid variables (mag. +3.5 to +4.4, with
   a period of 7.18 days), and it was found
   a month before his collaborator, John
   Goodricke, discovered the variability of
   Delta (b) Cephei, the star that gives that
   class of variable star its name.  SEEN IT
   5. Barnard’s E
   This is one of the easiest dark
   nebulae. You’ll find it 1° west of
   Tarazed (Gamma (a) Aquilae). It’s actually
   a pair of nebulae, B142 and B143, which
   stand out against the star-rich Milky Way
   background, making them easy to find
   and identify. Choose a dark transparent
   night if this is your first attempt at dark
   nebulae, and the obscuring gas and dust
   will appear either as an uppercase ‘E’ or
   an underlined ‘C’.  SEEN IT
   6. The Saturn Nebula, NGC 7009
   You’ll need dark, transparent skies for
   this nebula, but it is easy to locate:
   identify Nu (i) Aquarii and it is 1.3° due
   west. NGC 7009 will look like a defocused
   star but, even if you use a UHC (Ultra
   High Contrast) or O-III (Oxygen) filter,
   your binoculars won’t show the elongation
   that gives it its name.  SEEN IT

BINOCULAR TOUR

This month’s wide-field wonders include Barnard’s E and two globular clusters

Teaspoon

Water Jar

AQUILA

SAGITTA

DELPHINUS

EQUULEUS

PEGASUS

AQUARIUS

CAPRICORNUS

SCUTUM

SAGITTARIUS

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e

d

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b

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b

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Altair

Enif

Althalimain

Algedi

Dabih

Sadalmelik

Sadalsuud

Baham/Biham

Sualocin

Rotanev

Tarazed

Alshain

3

(^54)
24
M15
M2
M71
Collinder 401
M11
NGC 6709
IC 4756
NGC 6633
NGC 6572
NGC 6712
Collinder 394
NGC 7009
B142
B143
5 °
N
S
E
W
2
3
4
1
6
Tick the box when you’ve seen each one
54 BBC Sky at Night Magazine August 2021
With Steve Tonkin
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