southern hemisphere. Several supernovae have been seen
in it during recent years.
There is also a planetary nebula, NGC3242 (C59),
which has been nicknamed the Ghost of Jupiter. There is a
relatively bright oval ring, and a hot 12th-magnitude cen-
tral star; the whole nebula is said to show a bluish-green
colour, and it is certainly well worth locating. It forms a
triangle with Óand Ì, so that it is well placed for northern-
hemisphere observers.
Two now-rejected constellations border Hydra.
Noctua, the Night Owl, was sited close to Á(a rather
dim globular cluster, NGC5694, lies here), while Felis, the
Cat, nestled against the watersnake’s body south of Ï.
Generally speaking, these small and obscure constellations
tend to confuse the sky maps, but in some ways it is sad
to think that we have said good-bye to the Owl and the
Pussycat!
Corvusis one of the original constellations, listed by
Ptolemy. According to legend, the god Apollo became
enamoured of Coronis, mother of the great doctor
Aesculapius, and sent a crow to watch her and report on
her behaviour. Despite the fact that the crow’s report was
decidedly adverse, Apollo rewarded the bird with a place
in the sky.
Corvus is easy to identify, because its four main stars,
Á, ‚, ‰and Â, all between magnitudes 2.5 and 3, make up
a quadrilateral which stands out because there are no
other bright stars in the vicinity. It has to be admitted
that the constellation is remarkably devoid of interesting
objects. Curiously, the star lettered ·(Alkhiba) is more
than a magnitude fainter than the four which make up
the quadrilateral.
Crater, the Cup, said to represent the wine-goblet of
Bacchus, is so dim and obscure that it is rather surprising
to find that it was one of Ptolemy’s original 48 constella-
tions. It is not hard to identify, close to ÓHydrae, but there
is nothing of immediate interest in it.STAR MAP 7
The Antennae: colliding
galaxies in Corvus, NGC 4038
and 4039 (C60 and 61). (Left)
Ground-based view, showing
long tails of luminous matter
formed by the gravitational
tidal forces of the encounter.
Distance 63 million light-
years. (Right) Hubble Space
Telescope view: the cores
of the galaxies are the
orange blobs left and right
of image centre, criss-
crossed by filaments of dark
dust. A wide band of chaotic
dust, called the overlap
region, stretches between
the cores of the two galaxies.
The sweeping spiral-like
patterns, traced by bright
blue star clusters, show the
result of energetic star-birth
activity which was triggered
by the collision.BRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
30 · 09 27 35 08 39 31 1.98 K3 Alphard
46 Á 13 18 55 23 10 17 3.00 G5
16 ̇ 08 55 24 05 56 44 3.11 K0
Ó 10 49 37 16 11 37 3.11 K2
49 14 06 22 26 40 56 3.27 K2
11 Â 08 46 46 06 25 07 3.38 G0
Also above magnitude 4.3: Í(3.54), Ï(3.61), ̆(4.12), ‰(4.16), ‚(4.28), Ë(4.30).
VARIABLES
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
R1 3 29.7 23 17 4.0–10.0 Mira 390 M
U1 0 37.6 13 23 4.8–5.8 Semi-reg. 450 N
DOUBLES
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
 08 46.8 06 25 281 2.8 3.8, 6.8 A is a close
binary
‚ 11 52.9 33 54 008 0.9 4.7, 5.5 Difficult test
CLUSTERS AND NEBULAE
MCNGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
48 2548 08 13.8 05 48 5.8 54 Open cluster
68 4590 12 39.5 26 45 8.2 12 Globular cluster
83 5236 13 37.0 29 52 8.2 11.3 10.2 Sc galaxy
59 3242 10 24.8 18 38 8.6 16” 26” Planetary nebula
(Ghost of Jupiter)BRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
4 Á 12 15 48 17 32 31 2.59 B8 Minkar
9 ‚ 12 34 23 23 23 48 2.65 G5 Kraz
7 ‰ 12 29 52 16 30 55 2.95 B9 Algorel
2 Â 12 10 07 22 37 11 3.00 K2
Also above magnitude 4.3: ·(Alkhiba) (4.02).A small, dim group. The brightest stars are ·(Alkes) and Á, each of magnitude 4.08.
Alkes lies at R.A. 10h 59m 46s, dec. 18° 17’ 56”.HYDRACORVUSCRATERGa Atl of Univ Phil'03stp 2/4/03 7:37 pm Page 231