Star Hopping – with help from Dr. Duchek
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Last night I had two hours of dark skies before the moon arose and on a whim was using the 15-inch in its traditional, manual Dobsonian mode. (No power, no computer, no drive motors.) It’s simpler that way and I wasn’t looking for anything particularly difficult to find. I have a Telrad finder mounted on the scope and this appears to project a red target – concentric circles - on the sky background making it easy to find things as long as they can be seen with the naked eye. So I went for the easy stuff the first hour, like Mars, and the Pleiades star cluster. I wanted to see if all the Pleiades would fit in my wide-field – cheapy – GSO 42mm eyepiece as predicted. They did NOT. The field simply isn’t quite as wide as claimed, or something’s wrong with my math. Anyway, using the 15-inch on the Pleiades is like hunting grasshoppers with a 50-caliber machine gun - overkill. The Pleiades need a more modest approach – like ordinary 50mm binoculars.
Fainter clusters can be quite spectacular in the 15-inch, so I decided to go after the familiar trio in Auriga – M36, 38, and 37. This put me in star-hop mode. That is, I know the cluster I seek is below the level of naked eye visibility, but lies on a line between two bright stars, so I prowl down that line until I stumble across it. Kinda clumsy. John Duchek has created a wonderful little publication that you can get from him. It’s a collection of “Telrad Finder Charts” of the 300 “best” objects. He’s drawn from the basic lists – Messier, Caldwell – plus from a list created by the Royal Astronomical Scoety of Canada and another from the Saguaro Astronomy Club. (A piece of one of his charts can be seen at right. The concentric circle match what you see in the Telrad finder.)
He’s then created some 45 charts which show naked eye stars down to magnitude 6 – I’m lucky if I see to magnitude 5 in my light-polluted skies – and on these charts he’s printed the concentric circles of the Telrad target, centered on the faint objects. This allows you to mentally mark off just how many Telrad target fields you have to move – and in what direction – from a bright star to the object you want to see. And it works!
Duchek sells these on his Web site for $49. I own these charts, even though I have three telescopes with computers attached that will find anything I want with little-to-no special knowledge or effort on my part. So why do it the hard way? Because hunting stuff down can be enjoyable and educational. When you do it you have to become more familiar with the night sky – the context in which these objects exist. You begin to garner a better sense of the overall picture. Of course at other times – especially when I have visitors to the Observatory – I don’t want people standing around shivering while I spend five minutes on a hit-or-miss star-hop mission. That’s when the computers are handy. They’re also handy when you simply want to focus on the object and not on the search for the object. And I do that a lot.
You get 46 laminated pages, bound together loosely so they can sit flat, for $49. Is this the best approach out there to these charts? I haven’t a clue. There are some free, downloadable ones. I didn’t make an exhaustive search. I’m just saying I’m satisfied with these. I suggest you Google “Telrad Finder Chart” and do your own assessment.
Bottom line - I recommend Duchek’s assemblage of charts – or something similar - whether your telescope is on autopilot or not. It brings out the navigator in you – exercises the jellyware. Helps deflect Alzheimer's disease. ;-)
A very soft, very large, fuzzy haze
So what did I find this way last night? Well, first on the list actually was M33 in Triangulum. This is a huge, spiral galaxy – quite close and quite diffuse. Through most of my early amateur astronomy life I don’t think I ever saw it. If you want to see what it looks like to the camera – go here. http://www.astropix.com/HTML/A_FALL/M33.HTM But this is not what it looks like in the telescope. It’s one of those things I can point even a large telescope at, like the 15-inch, step aside, and ask a newcomer to take a peek – and they won’t see a thing. Not at first, anyways. It can be so subtle that you really need a good sense, gained only from experience, of what constitutes a black sky and what, when the sky isn’t black, you are seeing.
So who cares? You mean you freeze your butt off to see nothing – or something that’s next to nothing? No. I freeze my butt off to see 100 billion stars – each a magnificent, incredible nuclear furnace spewing out more energy in a fraction of a second then men could create in a millennium and yet this incredible fireworks display is so far away that I see it only as a faint haze. They are the whisp of smoke from candle snuffed out across the room. But back to the process – M33 is a difficult target to find and finding it quickly was evidence of the value of the Duchek charts.
The large, the small, and the misty
This is how the camera sees M31 and its small companions, M32 and M110. What the eye sees in the telescope is not this, though certainly awe-inspiring in its own way. Go here for a detailed discussion of this trio.
I went on to the much easier targets – naked eye, really – of M31, 32, and 110. These are three fascinating galaxies right here in our own neighborhood. M31 is the Great Andromeda Galaxy and is magnificent in even 50mm binoculars. Magnificent, that is, if again you understand that in this case the blob of light you are seeing represents the combined output of 300 billion stars that are about 2.7 million light years away. What I wanted to confirm was the look of Andromeda’s close neighbor, M32. I had just read an article that said it was one of the densest collections of stars known – and sure enough, it does look dense. In fact, it looks like little more than a large, out of focus star. That stands in stark contrast to the other galaxies near Andromeda, M110. It is more ghost-like – downright misty - sort of like M33, but smaller. And again, I have had visitors stare right at it and assure me they saw nothing. Needless to say, it is not a show-stopper!
Nor is M32. but again – knowing what you are seeing makes it far more interesting. (Found the article! It was in the “Ask Astro” portion of the January 2006 Astronomy magazine.) Where we hang out, in one of the spiral arms of the Milky Way galaxy, there is about five light years between stars on average. Not surprising, then, that the nearest star to our sun is 4.2 light years away –a humongus distance. But if we lived on a planet around a star in the densely-packed core of M32 we would find the average distance between stars was .008 – 8/1000th of a light year. That’s obviously a lot shorter so just as obvious, those folks are going to have a bright night-time sky – spectacular, really.
But here’s why all these numbers bug me: The article goes on to explain that this distance is the equivalent of 500 astronomical units. Now an astronomical unit is the distance between the Earth and the sun – about 93 million miles. If you really have a gut understanding – an experiential understanding – of 93 million miles, please step forward and announce yourself. I’d love to learn from you. Yes, I can appreciate that M32 has an incredible density of stars near its core – more so than what we find in other galaxies and certainly more so than what we are used to in our neighborhood. But I can’t begin to understand these numbers because they relate to nothing in my experience.
Oh – one nice thing I learned form my rambles last night was that M32 – which flanks M31 on one side – and M110 – which flanks it on the other side – fit nicely in the field of view of the 42mm GSO eyepiece. So with Andromeda high in the sky I’m looking forward to showing people these three galaxies all at once. No one will doubt they are looking at M31. I suspect most will find it a little difficult to determine at first which little blob of fuzzy light is M32. But what will be really interesting is to see how many can pick up M110 and if, perhaps, it’s easier to see when grouped with the other two, than when alone.