A Telescope In the City

Posted on October 14, 2010 by psu

I never expected to get back into telescopes. While they were my first hobbyist love and contributed indirectly to my final choice of career, the time of my real interest had long passed by. It also does not help that I live in the suburbs under a semi-permanent light dome coming from Pittsburgh. So no one was more surprised than me to be sitting in my back yard last night under a beautifully clear sky, peering once again into the darkness at the faint fuzzballs.

Let’s get one thing out of the way first, so the point does not get lost. An 8 inch Schmidt-Cassegrain telescope really is the perfect instrument for someone like me: an overly affluent dabbler. Aside from the comparatively modest cost, it has three characteristics that make it great:

  1. Relatively large aperture. This thing has four times the light gathering area of the Astroscan of my youth.

  2. Relatively portable size. The optical tube of the telescope is about the size of a small child, and about as easy to carry. More importantly, it’s small enough to be easy to store. I was really worried about this and for once the thing ended up being smaller than it looks in pictures.

  3. An automatic, computerized mount. We should talk more about this now.

The fact that the telescope has a computer that can accurately point at specific locations in the sky is simply invaluable. This is especially true in the suburban environment, where the sky glow would make it impractical to use even a large finder scope to “star hop” to you what you want to look at.

My main worry about this was how onerous the alignment process might be. Before the telescope can point at things, you have to tell it where it is. The quickest way to do this is as follows:

  1. Turn the telescope on.

  2. Point it at a first known star. You have to do this by hand. Put the star in the eyepiece and hit a button on the controller.

  3. Now the scope goes into a slower pointing mode so you can center the star in a higher power eyepiece. You do this very carefully. With Celestron telescopes, you also try to only move the star using the right and down buttons on the controller. This apparently helps to align the gears in the motor drive more effectively. When you are done, you hit the align button again.

  4. Now the telescope suggests a second star to point to. It goes there by itself, but it will probably miss. You then repeat step 3 for the second star.

  5. Now you are done.

If you have done your work well, my telescope (a Celestron 8SE) will now point accurately enough to put the object into the field of view of my 120x eyepiece. Right now that field is only around a third of a degree in diameter. Not bad. Even better, after you hit a target, the scope will automatically track it. You can leave the thing in the yard while you warm up in the house and then walk back out and have it still be in your 120x eyepiece. This is much more cool than I thought it would be.

Happily for me, it did not take much practice to figure out how to obtain this level of performance. Sadly for me, I got a lot of practice at this because the power cable on the telescope kept falling out because Celestron never fixes their stupid power connectors. Every time the cable falls out, you have to do the two star dance again. It only takes four or five tries to get good at it. Then I learned to put batteries into the telescope as a backup against the stupid power cable.

My other complaint is that the actual interface on the controller is ludicrously primitive. For example, if I want to see the Andromeda Galaxy, I have to type “M 0 3 1”. The stupid thing is not smart enough to actually parse integers for me. The menu system is also strange and hard to work with, especially since you only get to see 2 lines of text at a time. These interface problems are emblematic of an industry that is selling its main product (telescopes) on so little margin that actually investing in improving the interfaces is both too expensive and too risky. I mean, for god’s sake they still use RS-232 ports.

But, I will forgive them these foibles, because the way I find things now is to point the telescope at the object and then compare what I see in the eyepiece to a known chart. I can look the object up on my iPhone and have the phone display a chart of what should be in the eyepiece. As an aside, this is much nicer than fumbling with printed star charts. The StarMap Pro software is even smart enough to generally orient the eyepiece field correctly. And the iPhone screen, when it’s mostly black, does not completely destroy your dark adaptation.

Anyway, with the telescope pointed and the iPhone holding the chart, I can then look into the eyepiece, and see if the stars look right. Then I squint and stare until the back of my brain starts to leak out of my ears, and I decide if I think I saw anything.

For relatively bright objects (M31, the big globular clusters, etc) it’s usually pretty easy to pick out the faint fuzzy. Sometimes the view is even pretty impressive. More often than not though it’s hard to know if you actually saw what you thought you saw. Which is why this particular night made me so happy. I jumped over to the galaxy M82, which I had tried to see a few nights ago, and I only noticed a faint hint of its existence. But last night it was obviously there. A dim gray cigar shaped cloud right where the StarMap chart said it would be. Its brighter partner, M81 was also an obvious cloudy object when I pointed the scope there.

Finally, the last major success of the night was tracking down the Comet Hartley 103P. I had missed it when it passed by Perseus before. But tonight it was easy to see, as it had become a bit brighter in the intervening time.

Tonight my squint and stare fest was reserved for M110, a small galaxy that is near the much larger and brighter M31. I spent about 20 minutes going from the iPhone chart to the scope and back again and I think I got the faintest hint of its existence but I’m not sure. I’m a bit more sure of this than I was of M82 the other night though, so that’s a reason to be optimistic.

Overall this telescope has worked better than I ever imagined it would. More importantly, using it from a light polluted suburban back yard is more practical than I ever imagined it would be. I have a reputation for not being able to be pleasantly surprised by anything anymore, but here my friends is a counterexample for you. So there.

Extra Notes

I never would have gotten this far without the excellent writings of “Uncle Rod” Mollise. His weblog is good. His books are good. They made me believe the hardware would work for me.

One of the best things about amateur astronomers is that they are still relatively cheap people. You also have to love a hobby where a $300 lens (eyepiece) is considered to be staggeringly expensive. I’ll be ordering a couple of fancy eyepieces I think. Gotta see what the fuss is about. While I’m at it, I think one of those astronomical video cameras needs a home too.