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 Constellation Guide CASSIOPEIA

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scopeman

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PostSubject: Constellation Guide CASSIOPEIA   Fri Aug 26, 2011 5:21 pm

Cassiopeia - Queen - and mother of Andromeda



Pronounced "Cass - ee - oh - pee - ah"



Where to find the constellation









Constellation Chart









This whole area of the sky sees the story behind the movie 'Clash of the Titans' played out in the heavens.

Queen Cassiopeia, beside King Cepheus, and their daughter Cassiopeia - who was rescued by the hero Perseus, on his winged horse Pegasus.

The constellation of Cassiopeia is 'Open Cluster City' - so many, in such a small area of the sky. Two Messier open clusters, and one of my personal favourite open clusters - ngc7789, as well as a nice coloured double, and a tight triple star.

As well as the clusters I'm gonna specifically mention, there are MANY more in this very cluster-rich part of the Milky Way - several times I have sat with SkyAtlas 2000, and 15x70 binocs, trying to identify as many of them as I can - quite a challenge, because Cassiopeia sits smack-bang on top of the Milky-Way, and it can be difficult to seperate the clusters from the background stars on a clear night.





M52

'Fuzzball' of an open cluster in binocs - resolves into stars with a telescope.





M103

Loose open cluster, closer than m52, easier to resolve individual stars





ngc457

THe 'Owl' cluster - another loose cluster, gets it's common name from the fact that it can look a bit like an owl.

Look at this pic and slightly de-focus your eyes.





ngc7789

One of my favourite DSOs

This large, old, distant cluster has a strange property - If you observe it under just the right conditions, it gives the ILLUSION that it has a bit of spiral structure.

Obviously, this is no more than an illusion, but something worth looking for.

You need between 5" and 8" of aperture - good dark conditions - AND the right magnification (75x to 125x) to have a chance of seeing the spiral illusion.

Not enough aperture, low power, or poor skies, and you can't resolve stars to be able to tease the illusion out.

Too much aperture, or too much magnification, and the illusion is lost.

I've personally manged to see the spiral illusion maybe 10 or 12 times, out of, probably close to 100 attempts.







Some of the other Cassiopeia OCs are quite easy to see - such as NGCs 129, 7790, 663, 637

ngc225 is a very loose collection of 10 - 12 stars, but good skies and 6" or more, will show that many more are just at the edge of being
resolved.



Bubble nebula (ngc7635)

Near M52 - a faint emission nebula, part of which has been deformed int a bubble, caused by outflow from a powerful 'Wolf-Rayet' star.

Very difficult to pick out visually (Dark sky, large aperture, nebula filter) - but a beautiful photographic target.







Eta Cassiopeia

Nice Yellow and Red double - 13 arcsec separation - Yellow primary is mag 3.6 - red secondary at 7.5



Iota Cassiopeia

Tight triple star - all elements are white - magnitudes A = 4.7, B = 7.0, and C = 8.2

Separations:- A-B 2.3 arcsec - A-C 7.2 arcsec

Seeing the C element, is fairly easy, but the challenge is picking out the B element, so close to the glare of the primary.

Image from Starry Night shows their orientation.







Cassiopeia NGCs (with magnitudes) - from my own "1200 Northern NGCs" list

For those with 'GoTo' or a good chart

129 - OC - 6.5

147 - Gal - 9.5

185 - Gal - 9.2

225 - OC - 7.0

278 - Gal - 10.7

281 - OC - 7.4 (Pacman neb)

457 - OC - 6.4 (Owl cluster)

559 - OC - 9.5

581 - OC - 7.4 (m103)

637 - OC - 8.2

654 - OC - 6.5

659 - OC - 7.9

663 - OC - 7.1

7635 - Neb - 11.0 (Bubble Nebula)

7654 - OC - 6.9 (m52)

7789 - OC - 6.7

7790 - OC - 8.5
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astrolover

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PostSubject: Re: Constellation Guide CASSIOPEIA   Fri Aug 26, 2011 5:53 pm

excellent this is one of my favs as it is right in the line of fire.
glad you posted this one Very Happy Very Happy
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TomK

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PostSubject: Re: Constellation Guide CASSIOPEIA   Fri Aug 26, 2011 5:54 pm

Thanks - another excellent job.... Lots in this one!
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Clive_D



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PostSubject: Re: Constellation Guide CASSIOPEIA   Fri Aug 26, 2011 5:54 pm

Bookmarked this page for future use. Very useful guide.Thanks
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