Particulars:
General:
This beautiful constellation at the edge of the Milky Way has
definetely the shape of a "W". It is assiociated with
the Perseus constellation family.
Sweeping this region with binoculars (or even an opera glas) is
rewarding (especially the region around delta Cas).
It is located between DECL=+50 and DECL=+60, RA=23h and RA=3h.
Once you found Cassiopeia or the Big Dipper, which is located
opposite of the celestial pole, you can easily locate other
constellations of the northern hemisphere.
In arabian countries this constellation is called Caph,
which is also the name of beta Cas.
Stars and other objects
The leading star, alpha Cas, also called Shedir
(arab.: the breast), is an irregular variable star (K0IIIa),
which forms with an 9th mag blue neighbour an optical double star
(i.e. not physically related).
Gamma Cas, sometimes called Tsi (chin.:
the whip), is an unstable blue subgiant (spectraltype B0IVe),
that throws off shells of gas at unpredictable intervals. So it
brightness vary between 2nd mag and 3rd mag.
The double eta Cas consists of a yellow (G0V) and a red
component (M0) and is really beautiful in small telescopes. The
two stars are of 3.44 mag and 8th mag, respectively.
A nice triple star is iota Cas. In small telescopes a 8th
mag companion to the white star of 4.5 mag is revealed. The
brighter component has a close 7th mag companion, but for
separation a telescope with an apertur of at least 100 mm and as
high magnification is needed.
Another variable star is rho Cas. This yellow star can be
viewed with the naked eye. Its variation period is unknown. (?)
In this region one can find lots of nebulae and open clusters:
The diffuse nebula I 59, lying next to gamma Cas
consists of two fans pointing northwest.
One degree west of alpha Cas you find the diffuse nebula NGC
281.
The planetary nebula NGC 7635shows up an high total
brightness; yet it appears faint due to its large extension. A
nice object even for small telescopes.
Of the hole bunch of open clusters the two Messier objects M52
and M103 may be best known. The first is somewhat kidney-shaped
and contains over 100 stars. Its a good object for binoculars
showing a prominent 8th mag star at one edge. The second Messier
object has the shape of a fan and at least 40 members (for more
information about both objects please refer to the Messier
Database).
From the other clusters NGC 457 should be mentioned for it
is one of the brightest in the sky and an attractive object for
small telescopes; its stars seemed to be arranged in chains. Also
good viewable it the 5th mag yellow supergiant phi Cas
(spectraltype F0Ia).
Mythological Background:
Long ago in ethiopia Cassiopeia has been the wife of Cepheus
and the mother of Andromeda. Because she thought herself more
beautiful than the daughters of Nereus, a god of the sea, she
challanged the anger of the god Poseidon. To punish her, her
daughter was chained to a rock of the coast as a sacrifice for a
sea monster. Andromeda was saved from death by Perseus. (Publius
Ovidius Naso: Metamophoses, IV)
To learn humility Cassiopeia was banned to the sky hanging half
of the time head downward.