Cassiopeia The Queen
The Cassiopeia star field. Credit: Stellarium
By Mike Barrett
Cassiopeia is a prominent constellation in the
northern hemisphere which is very easily recognised
as a W or M in the night skies. In most of Continental America and all of Europe it is visible year round
but becomes most spectacular in the winter months,
when it is elevated to a much higher altitude.
Along with The Plough (Ursa Major) The Queen (Cassiopeia) is one of the first constellations that is learnt in the
heavens above. The five main stars of the constellation are
quite similarly matched varying from magnitude 2.15 to
3.35 making it very easy to pick out,
especially from a light-polluted site
or when the moon is shining brightly.
Cassiopeia lies within the main
band of the Milky Way. From a
very dark viewing site, when there
is no Moon the millions of stars
forming the star field of our galaxy
can be seen as a wispy cloud.
Using binoculars pulls a lot of the
faint stars into detail, and you will
suddenly see a mass of stars popping out of the background stellar
clouds. Moving up to a telescope
will reveal many more stars and
the beauty of the region. In fact,
with binoculars and telescopes
M52 and the Bubble Nebula.
so many stars can be seen that
it is difficult to navigate around the constellation.
As you would expect with an area in the Milky Way
there are lots of deep sky objects to be seen and imaged. Most of these are quite dim and will require
binoculars or a telescope to see. Some, though spectacular, are not visible to the eye but reveal themselves with deep sky photographic techniques.
The open star clusters of M103, NGC 7789, and
M52 are easy to find and delightful to view. There
are also: NGC 457, the Dragonfly Cluster; NGC 225,
the Sailboat Cluster; NGC 663 or Caldwell 10; and
many other smaller and fainter star clusters
M52 is the easiest to locate as you just follow a
line up from the two rightmost stars of the ‘W’ and
continue on about the same distance. With a modest 3-4” telescope you will be able to see a lot of
hot, blue stars and a few older, cooler yellow stars.
Switching from an eyepiece to an image sensor you
can start to explore the deep sky objects of the constellation. Just below M52, and in the same field of view in a
3” telescope, is NGC 7635, The Bubble Nebula. The Bubble Nebula is a hydrogen emission
nebula that has a cloud of hydrogen gas, with the bubble forming a
shell in the centre of the gas cloud.
Moving to the opposite end of
the constellation are two very large
hydrogen emission nebula named
the Heart and Soul Nebula. These
are supposedly visible through a
telescope, but I have never seen
them. They are also huge, spanning an area 10 times wider than
the Moon and eight times as high.
The best way to see this pair is
by using a camera. The problem
with that is that the light they emit
is in the far red area which traCredit: Mike Barrett
ditional cameras cut off, along
with Infrared light. So the ideal way to photograph them
is using a modified camera with a normal lens. I have
found that a 200mm lens just about fits them in frame,
but you have to be very careful with the framing.
NASA has an Infra Red telescope in orbit called
WISE. This camera created a false colour image by
sampling light using a number of narrow band filters
and assigning colours to them. As you can see on the
next page, this creates an image vastly different to
the normal red nebula or Hubble palette images.
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