is none too easy to locate; it lies between ıCapricorni
and ÂAquarii (not shown), and is surprisingly difficult to
resolve into individual stars.
M73, less than 2 degrees from ÓAquarii (magnitude
4.51), is not a real cluster at all, even though it has been
given an NGC number; it is made up of a few discon-
nected stars below the tenth magnitude.
There are two interesting planetary nebulae in
Aquarius. NGC7009 (C55), the Saturn Nebula, is about
one degree west of Ó, and is a beautiful object in large
telescopes, with a prominent belt of obscuring material. It
is about 3900 light-years away, and around half a light-
year in diameter.
NGC7293 (C63), the Helix Nebula, is the largest and
the brightest of all the planetaries, and is said to be visible
in binoculars as a faint patch, though a telescope is needed
to show it clearly because it lies so close to Ó. When
photographed, the Helix is seen to be not unlike the Ring
Nebula in Lyra (M57), but the central star is only of the
13th magnitude.
Piscis Australis, or Piscis Austrinus, is a small though
ancient constellation, apparently not associated with any
myth or legend.
The only star above the fourth magnitude it contains
is Fomalhaut, which is the southernmost of the first-
magnitude stars visible from the latitudes of the British
Isles (from north Scotland it barely rises). It is easy to find
by using ‚and ·Pegasi, in the Square, as pointers; but
beware of confusing it with Diphda or ‚Ceti, which is
roughly aligned with the other two stars of the Square,
Alpheratz and ÁPegasi. However, Diphda is a magnitude
fainter than Fomalhaut.
Fomalhaut is a pure white star, 22 light-years away
and 13 times more luminous than the Sun; it is therefore
one of our closer stellar neighbours. In 1983, the Infra-
Red Astronomical Satellite found that it is associated with
a cloud of cool matter which may be planet-forming; as
with Vega, ‚ Pictoris and other such stars, we cannot
certainly claim that a planetary system exists there, but
neither can we rule it out, The Southern Fish contains
nothing else of particular note, though ‚is a wide and
easy optical double.STAR MAP 14
Globular cluster M2 in
the constellation Aquarius,
photographed by Doug
Williams and N. A. Sharp
with the 0.9-m (36-inch)
telescope of Kitt Peak
National Observatory.BRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
49 ‰ 21 47 02 16 07 38 2.87 A5 Deneb al Giedi
9 ‚ 20 21 00 14 46 53 3.08 F8 Dabih
Also above magnitude 4.3: ·^2 (Al Giedi) (3.57), Á(Nashira) (3.68), ̇(Yen) (3.74), ı(4.07), ˆ(4.11), Ê(4.14),
·^1 (4.24), È(4.28).
DOUBLE
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
· 20 18.1 12 33 291 377.7 3.6, 4.2 Naked-eye pair
‚ 20 21.0 14 47 267 205.0 3.1, 6.0
CLUSTER
M NGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
30 7099 21 40.4 23 11 7.5 11.0 Globular clusterBRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
22 ‚ 21 31 33 05 34 16 2.91 G0 Sadalsuud
34 · 22 05 47 00 19 11 2.96 G2 Sadalmelik
76 ‰ 22 54 39 15 49 15 3.27 A2 Scheat
Also above magnitude 4.3: ̇(3.6 combined magnitude), 88 (c^2 ) (3.66), Ï(3.74), Â(Albali), (3.77), Á(3.84),
98 (b^1 ) (3.97), Ù(4.01), Ë(4.02), ı(Ancha) (4.16), Ê^1 (4.21), Ù(4.22), È(4.27).
VARIABLE
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
R2 3 43.8 15 17 5.8–12.4 Symbiotic 387 Mpec
DOUBLE
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
̇ 2 28.8 00 01 200 2.0 4.3, 4.5 Binary, 856y
CLUSTERS AND NEBULAE
M C NGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
2 7089 21 33.5 00 49 6.5 12.9 Globular cluster
72 6981 20 53.5 12 32 9.3 5.9 Globular cluster
63 7293 22 29.6 20 48 6.5 770” Planetary nebula
(Helix Nebula)
55 7009 21 04.2 11 22 8.3 2”.5 100” Planetary nebula
(Saturn Nebula)
M73 (NGC 6994), R.A. 20h 58.9, dec, 12° 38’, is an asterism of four stars.BRIGHTEST STAR
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
24 · 22 57 39 29 37 20 1.16 A3 Fomalhaut
Also above mag. 4.3: Â(4.17), ‰(4.21), ‚(Fum el Samakah) (4.29).
DOUBLE
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
‚ 22 51.5 32 21 172 30.3 4.4, 7.9 (Optical)CAPRICORNUSAQUARIUSPISCIS AUSTRALISGb Atl of Univ Phil'03stp 2/4/03 7:42 pm Page 245