- Brandon Vernonscope 94mmF7 APO first impressions.
- A quick review of the iStar Phantom FCL 140-6.5
- Explore Scientific, 16 inch / F 4.5 Truss tube Dobsonian
- Celestron PowerSeeker 70AZ Telescope ($10 Scope)
- Orion EQ-26 Mount Review
- Review of Explore Scientific First Light 8
- Rebuilding my CGE Pro
- COUNTING SUNSPOTS WITH A $10 OPTICAL TUBE ASSEMBLY
- Hubble Optics 14 inch Dobsonian - Part 2: The SiTech GoTo system
- iStar Optical’s Phantom FCL 140-6.5 review
- Who’s Afraid of a Phantom: Istar Phantom 140mm F/6.5, that is?
- SHARPSTAR 94EDPH APOCHROMATIC REFRACTOR
- My Losmandy G11T review
- FIELD TEST: THE NOH CT-20 ALT-AZ MOUNT
- SkyTee-2 Alt/Az Mount Review
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Small Wonders: Cassiopeia
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|Small Wonders: Cassiopeia
A semi-monthly observing column
By Tom Trusock – 11/2005
Cassiopeia Widefield Finder Chart
The PDF is here
It’s time to pay homage to the Queen. In late fall and early winter we see the annual ascent of Cassiopeia, Queen of Ethiopia, wife of Cepheus and mother of Andromeda. (This is the rise of the big W in the northern sky to those of you less versed in ancient lore, but more familiar with the night sky.) Although Cassiopeia is a late riser when compared to other members of her family, there’s little question – at least to this observer – that she’s the one in charge. Doubt me?
Well, let’s take a minute and examine the evidence, shall we? Obviously, compared to the rest of her family, she’s a late riser. That’s a given. While poor old Cepheus is up and about the business of running the kingdom, she hasn’t even peeked above the horizon – no, she gets to sleep in. And then there’s the whole chair bit. She’s the only one in her entire family that’s seated! Now, my wife tells me it’s because she’s been up all night with the children, but in my book, poor old Cepheus has been up just as long and he’s forced to stand! Finally – as if you need more evidence – just take a look at her jewelry. Cassiopeia, being smack dab in the middle of the winter milky way is a true treasure trove for all sorts of flashy ornaments – and it’s those that we’re interested in tonight. She does get her comeuppence of a sort – while sitting in the chair, half the time she finds she's upside down. According to some sources this is punishment for her boast that she was even more pleasing to the eye than the sea nymphs. Ahh, vanity.
Well, on to the celestial targets. First off, we’ll take a look at a few of her solitaires: Alpha – better known as – Schedar, Eta – or Achird, Gamma, Iota and – well, what was once one of her shining jewels - Cassiopeia A.Schedar is the brightest star in Cass, although not by much and not all the time as it can be surpassed in brightness by the variable star Gamma. Gamma itself is unique as it’s held by some to be a binary star system that contains a Be star and a neutron star and is the brightest x-ray binary star in the night sky – to my knowledge no other x-ray binary can be seen with the naked eye.
Trivia – the first voyagers to the Centauri star system will see Sol near epsilon at about .5 mag in brightness.Achrid is a well known binary that the NSOG informs us was discovered by Sir William Herschel in August 1779, the period is around 500 years, and the separation varies between 5” and 16”. It’s purported to see be multiple colors – heavily dependent on the aperture you use to view it with. Take a look for yourself.
Cassiopeia A (RA 23:23.4, Dec +58:50) is the youngest known supernova remnant in our galaxy having exploded sometime around 1667. Opinion on who was the “discovery” observer is divided – some feel that John Flamsteed cataloged it on August 16, 1680 – others point out that the “star” he cataloged has nothing exactly corresponding to it’s position, and that he simply made an error. Other than that, the first time it stepped into the limelight was in the late 1947’s when it was cataloged as the strongest radio source in the sky (excluding solar system objects) and given the designation Cassiopeia A and received the designation 3C 461 in the third Cambridge survey. While it’s not a visual target per-se, it is a fairly interesting object located in Cass.
Iota is a challenging triple,
namely in seeing how small of an aperture and low of a magnification can split it – take a
minute if you have clear skies and give it a go. Here’s an image
contributed by Simon Walton - one of our longtime readers. You can get an idea of the main difficulty you'll be facing. Iota's actually a triple star. To give you an idea here, the magnitudes are 4.5, 8 and the closer companion is listed as mag 7 (you'll probably need at least a 4" to see all three).
For the DSO’s this month, we’ll start with the western edge of the W, and follow along hitting our targets as we go. Just a few short degrees from Beta, we find three objects worthy of telescopic inspection.First up, we’ll stop at NGC 7789. This has to be one of my all time favorite open clusters. Ok, sure, you probably hear me say that nearly every month, but hey – it’s true! And doubly so this time. This object looks amazing in nearly any size telescope. I’ve viewed it with scopes as small as 60mm refractors to monster 20 inch dobsonians – and they all had something to offer. Smaller scopes can expect a mist that breaks into pinpoints of light as conditions or aperture increases. Large scopes can see hundreds of individual stars that, to me, have a very evident rose or whirlpool effect – although to the best of my knowledge, I’ve never heard any other observer describe it that way. If you have a large scope, please take a look and tell me what you see. Is this simply my overactive imagination at work? Or is my brain pulling out a subtle pattern but existing pattern? Intermediate scope users most likely won’t see any sign of the whirlpool, but they will see an extremely rich concentration of both resolved stars and the background mist that indicates hundreds more lying just beyond the resolution limits of their equipment.
This cluster should be visible with any form of optical aid, and I’d suspect you could even see it naked eye from a suitably dark and transparent site. Anyone care to put this theory to the test?
Eric Graff’s wonderful sketch is an excellent depiction of what to expect through a 4-6 inch telescope from a moderately dark site.
Next, lets head just north, and over to a chain of clusters – the two brightest being NGC 7790 and NGC 7788.As you can see, there are a total of six clusters in the immediate area, five of them in a chain. For the small scope user, simply concentrate on finding 7790 and 7788. These two clusters are the brightest in the chain and will probably be seen as a general mist with a few defined stars from a moderately dark site in a small telescope.
The other clusters I’ve found to be more of a target for larger telescopes, detailed maps and much patience. Frankly, I’ve often had a difficult time picking open clusters out of the Milky Way background – it’s sometimes difficult to tell where one cluster leaves off and the background begins.Spend some time here and see how many you can make out.
Dropping further west, we come to one of the two Messiers to be found inside the Cass border – open cluster M52.
According to some of the latest astrophysical data, M52 is some 20 million years old, measures 24 or so light years in diameter and contains over 200 members. Telescopically, I find M52 a very rich, very pretty star cluster.
I’ve found different apertures and magnifications tend to present very different views of M52 and it’s environs. Stephen James O’Meara sees M52 as a stellar arachnid – I’ve not noted that, but it is a mesmerizing group of stars nonetheless.
M52 and the Bubble Nebula – Contributed by Dean Rowe
If you see a faint glow in the area, you aren’t imagining things – no, just a few arc minutes southwest of M52 we find the Bubble reflection nebula (NGC 7635) – make sure to take a look for this if you’re observing from dark skies with a large scope. Take a few minutes and try a UHC filter to see if it improves the view.
After you’ve finished, let’s head back to the W and move east.
Forming a triangle with Alpha and Eta, we find the emission nebula / open cluster NGC 281. In smaller scopes look for hazy glow. Exactly what this is, I'm not positive. It's either the unresolved cluster, or the nebula itself. I’ve never been able to determine. Larger telescopes begin to show stars associated with the cluster, and again, I’d recommend that you try a UHC filter to see if it enhances the contrast and helps to better define the nebulosity.
NGC 281 – Ralph McIntosh
Unfortunately, we can only imagine seeing it as Ralph McIntosh has captured it.Once you have found 281 do take the time to inspect it in detail. So many observers today are of the GOTO tourist variety. You know what I mean - Plug in the numbers, slew to the target, take a quick peek and on to the next we go. That’s a disservice to nearly every target – and this one in particular. Try it filtered and unfiltered. Use different eyepieces and vary the magnification – look for unevenness in the nebula – bright and dark patches. Do you see stripes? Knots? Whirls? Or is it uneven and featureless? Spend some time here and take some notes about what you observe. When you’re ready, move east again, this time to NGC 457.
Variously called the ET, Alien, Ghost, or Airplane cluster, this is a wonder that Messier somehow missed and a sure favorite at fall star parties. I tend to see it as either an alien or an airplane. The two bright stars at the top right of Eric’s drawing serve as either the eyes or the engines. The scattering of stars just below them are the outstreached arms or the wings, and the body continues on down.
Reader Brian Carter has this to say about observing 457 in a 10” Dobsonian:
To me it is an almost perfect replica of the Gemini constellation. the 2 dominant stars, maybe 8-9 mag, are in the same position as Castor and Pollux. Other stars make up the respective legs and arms of the twins. There are a number of 'dark' red stars, like dim carbon stars. This is one of my favorite clusters, really stimulates the imagination.
I remember the very first view I had of this cluster, oh-so-many years ago. I stumbled upon it with my 8” dobsonian, had no idea what I was looking at, but must have spent an hour simply staring at the view. Personally, I find this probably the most impressive cluster in Cass – for a small telescope anyway. Although 7789 gives it a real run for it's money.If you’re interested in reading more about this cluster, I highly recommend The Caldwell Objects by O’Meara. For reference, NGC 457 is Caldwell #13.
Moving on down the W, to the NE, just off Delta, we find Messiers other object for Cass – well, technically, I guess it’s not REALLY Messiers – as in Messiers find anyway, but it is entry 103 on the Messier list. Discovered by Messier’s friend Pierre Mechain in 1781, ironically, this is the last object in Messiers’s original catalog. In the past, there’s been some debate as to the genuineness of this open cluster, some have seen it as a random association, but modern data tends to confirm its existance as an associated group of stars. Personally, I find that M103 is best viewed at low powers and in small scopes. Large aperture and high powers tend to overwhelm the cluster and it looses it’s attraction.
M103 - Jeremy Perez
I particularly like Jeremy Perez’s sketch of M103. In my opinion, a nice low power view that shows the surrounding area well is the best way to view this cluster. With it’s distinctive triangular shape, some observers have called it the Christmas tree cluster, but that’s never been really apparent to me. An ornament, perhaps – especially with the colorful stars scattered throughout and nearby. Either way, let it serve as a reminder that very very soon many of us will be clearing off the residue from a massive turkey dinner and hauling out all those Christmas decorations. Heck, I don’t know about you but the Wally World by me has all of the Christmas stuff out already.
Lets move NE again, and this time we’ll come across a nice collection of clusters – 663, (The horseshoe cluster), 654 and 659 are the three dominant, but there are a plethora of others scattered throughout the area. As you can tell from the wide field composite DSS image above, this is a very crowded area and certainly deserves some time with a small (or large for that matter) telescope. The two most interesting clusters in the photo above, I find to be M103 and NGC 663, but the others are worth a visit too. In fact, if you have a wide field scope, pop in your widest eyepiece, take out a chart and just spend an evening seeing what you can spot in this (and surrounding) area(s).
NGC 663 – Jim Thommes
Finally, we come to a few extra-galactic targets. Consult the wide field map and head back to the other end of Cass where we’ll literally go off the deep end for these two. Then use the chart just below to help narrow the field.
about Andromeda’s satellites and people think M32 and M110 – well,
they’re missing two others that can easily be spotted in a small scope.
Well, we'll go off the beaten path a bit to show you a couple more: NGC 185 and NGC 147.Separated by about a degree, a sufficiently low power and wide field will show both of these in the same view. While they are somewhat small (at least compared to M31), they are also surprisingly bright. I’ve managed to pull both out in a small scope from a dark site on an excellent night, but I’d go so far as to recommend a 6-8” telescope would be more the norm for these two for observers working under "typical" conditions.
Don’t expect a lot of detail – like most galaxies, there just isn’t any. They are two little puffs of intergalactic cotton. Your reward is seeing some little known extragalactic satellite galaxies for one of the most popular deep sky targets ever. I’d wager that few amateurs even know these exist, and fewer still grasp the significance.
There are two more galaxies this month – one shouldn’t be particularly difficult, but I think I hit it on a poor night, and am therefore placing it in this category.That one, the first, is IC 10.
A faint but definite blob in the 18” at around 250x, the poor conditions made me think that this would probably be a fairly easy catch on a different night. So, your homework assignment - What’s the smallest scope you can grab IC 10 with? Please note all the details - conditions, eyepiece (type and focal lenght please) and, of course, size of the telescope.
The other challenge object this month is a
little harder, but - at least to me - vastly more interesting.
Oh, not for what you can see, but what it is.
Found near the Perseus border, Maffei1 is the largest galaxy in the Maffei 1 galaxy group (also called the IC 342 group). These lie very close to the galactic plane and thus tend to be obscured by heavy amounts of galactic dust and gas. The (major) known group members include IC 342, Maffei 1, Maffei 2, Dwingeloo 1 and Dwingeloo 2, with additional candidates suspected.
According to SEDS, W.E. Denning discovered IC 342 in 1895, Paolo Maffei discovered Maffei 1 and 2 in 1968, while Dwingleoo 1 and 2 were discovered in 1994 and 1995 respectively.
The Maffei 1 group was probably once a member of the local group, but was ejected because of an encounter with M31. Since then, they have moved out to about 10 million light years distant and continue to move away. If it weren’t for the intervening gas and dust in the Cassiopeia Milky Way, this giant elliptical would probably be one of the most spectacular galaxies in the night sky. That we can see it at all, is a testiment to it's greatness.
If you go after Maffei, do it with as much aperture as you can get your hands on - I'd suggest a minimum of 12-14 inches. Sucessful amaterus stress that you need to; ensure you have good charts and be prepared for some haze with a small group of foreground stars. It's too easy to think you're looking at an unresolved (or partially resolved) galaxy and not a largely unresolved cluster.
This is one of those targets, not so spectacular for the views it provides, but for what it is.
Betcha didn’t think a mere 10 million light years would get you out of the local group of galaxies, eh?
A special thanks to all who contributed this month – there were many, and picking through photos, and sketches is always enjoyable – I only wish I could use every image and description that was sent in.
Well, that's pretty much it for this month. I know, I know there's a lot more I could have covered, and if you saw the initial list, there was a lot more I thought about. I'm sure I skipped a lot of amateurs favorite targets - If you find yourself wanting more, here are a few suggestions (not exactly applicable to all telescopes - do your research first
And those should give you an additional night or two of observing.
Till next time –Clear Skies!
Tom T.Additional Reading/Resources:
Cassiopeia A and Supernova 1680 or 1667
The Maffei 1 Group of Galaxies (also IC 342 Group)
Small Wonders Home Page (More SW here):
I'd love to hear of your experiences under
the night sky - please feel free to