Star Hopper.

Explaining the wonders of the night sky.

Finding Cassiopeia.

Cassiopeia is fully visible throughout the year between lattitudes 90 degrees north down to 12 degrees south. The best time of year to see the constellation is Winter mid evening, between 2000 October through to December, or 2100 November through to early January depending on your location. It is Opposite Ursa Major from Polaris, or between Andromeda and Ursa Minor. The constellation resembles a W or M depending on your orientation to the sky and the time you are observing it.

Constellation Guide.

Interesting Stars.

Deep Sky Objects.

These lists and guide are by no means exhaustive, but I hope they help in finding something to look at, and I am determined to keep them up to date and accurate. So any mistakes or additions you would like, let me know.

Constellation Guide.

 

Links to the above image:

Interesting Stars.

Eta Cassiopeia : Located near the centre of the 5 stars in the asterism is an attractive binary star composed of a yellow star at a magnitude of 3.5, and an orange star of magnitude 7.5 which can be split by small telescopes.

  • The colours become more dramatic with twilight skies as the main star is 40 (4 magnitudes)  times more luminous than its companion.
  • They are around 70 AU apart and take around 500 years to orbit each other. They are located just under 20 light-years from us.

Gamma Cassiopeia (Ruchbah) : Located as the centre of the W that forms Cassiopeia.

  •  Gamma Cas is  a young star, only recently having collapsed from a dust cloud and beginning shine from the reaction at its core. When the reaction begins, new stars tend to throw out jets of gas, which heat up nearby gas clouds and cause them to glow.
  • Gamma Cas is surrounded by such an object, called an Herbig-Haro object (only visible through larger telescopes) An other sign of the stars youth is its varying magnitude, normally shining at magnitude 2.5, but it can vary between 3.0 and 1.6 . The luminous nebula are known by their IC numbers. IC59 is a reflection Nebula illuminated by Gamma Cas, and IC63 is an emission nebula, charged by the radiation from the star.

Iota Cassiopeia : To find this star, trace a line along Delta and Epsilon Cas and continue roughly the same distance between them, heading away from the constellation, until you find a fairly bright star, Iota Cas, which is easily visible even with the naked eye. 

  • Through a small telescope it is simple to differentiate between the two main components, and on a clear night a third can be seen as a small bump on the brighter star.
  • Iota Cas is a quadruple star, but the 4th component is difficult to make out with small telescopes, as they are located 170 light-years.

RZ and SU Cas : These variable stars can be found by continuing the line from Delta and Epsilon Cass, through Iota Cas about half the distance further. Both normally appear bright, RZ is the top (bottom in uncorrected telescopes) and SU is the bottom (top in uncorrected telescopes)

  • RZ and SU Cas should fit inside a telescopes FOV at lower power. Usually they are the brightest stars in their area, but RZ at its lowest magnitude is comparable to surrounding stars, whilst SU remains the brightest star even at its dimmest.
  • RZ Cas is an eclipsing binary, appearing at magnutide 6.4 most of the time, every two days, in the space of two hours it drops to magnitude 7.8 , about a quarter of it's original brightness, then returning to 6.4 in an other two hours.
  • SU Cas is a Cephid variable, a pulsing star located around one thousand light-years from us. SU Cas varies in brightness from magnitude 5.9 to 6.3 over a period slightly shorter that two days.

Rho and Sigma Cas : Follow the directions to NGC 7789 to find these two stars, the directions can be found at the bottom of the page.

  • Sigma Cas is a double star, but proves difficult to resolve into its two component stars. The main star is magnitude 5, and the companion star is 7, both are blue.
  • Rho Cas is a very old, variable super-giant star, often shedding large amounts of material, leading us to believe it is nistable, and nearing the end of its lifetime, possibly going nova. It is one of the brightest stars in the galaxy, but is over two thousand lightyears away.

Deep Sky Objects.

Caasiopeia is home to two Messier catalogue objects and a wealth of Clusters, as well as the nebula mentioned around Shedar.

NGC Items in Cassiopeia.

NGC 129 : This is an open star cluster found roughly half way between Epsilon and Beta Cas.

NGC 225 : This NGC is a small cluster located between Epsilon and Kappa Cas, resembling a small feiant spot in binoculars or a finder scope.

  • Under high magnification, it resembles a half circle of roughly a dozen stars, mith a pair of stars in the centre, and more stars are visible or hinted at using averted vision, as well as a hazy patch to the west.

NGC 457 : One of the highlights of the northern sky, this cluster is often called the Owl or ET cluster, due its resemblance to them.

  • Found roughly on a line between Delta and Theta Cas, you will find a bright star called Phi Cas, southeast of this star you will find the Owl cluster.
  • The two brightest stars form the "eyes" and the rest of the cluster is made of approximately one hundred and fifty visible stars varying between magnitude twelve to fifteen.

NGC 637 : This is a small cluster of twenty stars, less than five light-years wide, around five thousand light-years from Earth.

  • To find NGC 637, draw a line between Epsilon and Kappa Cas, NGC 637 sits around one and a half to twice a telescopes FOV at low power along this line.

NGC 663 : If you draw a line from Delta Cas to M103, and continue it twice that distance, you will find NGC 663.

  • This cluster looks like a small group of around 16 yellow stars with a feint haze of light in the background.

NGC 7635 : This nebula is difficult to see even in larger telescopes, but photographs well. The solar wind of a very hot star blow a bubble on the gas, creating an emission Nebula.

  • To find this nebula, trace a line along Alpha and Beta Cas, along to M52, then roughly one FOV at low power down, you should see a feint haze around a star, this is NGC 7635.

NGC 7789 : To find this, trace a line from Kappa through Beta Cas, If  you are using a finder scope, you should have two stars  near the centre of your FOV, with Beta Cas right on the edge, these are Sigma and Rho Cas, NGC 7789 is in between these two stars.

  • This is a large cluster of around one thousand old stars, predominately consisting of red giant and super giant stars, making the age of the cluster at over a billion years old.
  • The stars cover a field around forty light-years across, nearly five thousand light-years away.

Messier Objects in Cassiopeia.

M52 : Draw a line from Alpha to Beta Cas, then the same distance again, this will leave you at a dim star called 4 Cas, aim slightly south of this at a faint haze, this is M52.

  • Through a telescope it appears as a handfull of individual stars, set in a faint haze of light, averted vision reveals texture in this haze, hinting at stars that have not quite resolved in the FOV.
  • The clusters most prominent feature is a star with a magnitude of 8 on the southern edge, and several dimmer stars to the east.

M103 : If you move your FOV half way between Delta and Epsilon Cas, M103 should appear in the top right of your FOV, simply centre on it and go to a higher power to enjoy it.

  • Although a small cluster of around 25 stars, it is dominated by a giant orange star near the centre.