January 2008 Archives

The Moon, A Nebula, and a Not-a-Nebula

The weather finally let up, so I took the telescope out for a whirl this evening. Tonight's stargazing qualifies as a success.

First off, the Moon is back after a prolonged absence, so I was able to use it to align the viewfinder (the Moon is more than a mile away, fortunately), and give the Barlow lens and more powerful (10 mm) eyepiece a solid test run. The Barlow lens doubles the magnification of whatever eyepiece you pair it with. With the Barlow lens and the 10 mm eyepiece, the Moon was enormous. Lots of detail, very sharp shadows, and craters I felt like I could touch. Next time I'll look for the American flag.

I was also able to finally spot the Orion Nebula, using the freshly aligned viewfinder. Here the 10 mm eyepiece was less useful. As I've mentioned before, the thing is so sensitive to ambient light that it's like looking through sunglasses. I could tell that the nebula was better defined using the higher-powered eyepiece, but I just couldn't see it very well. The Barlow lens with the weaker eyepiece, however, provided a great view of the nebula.

I had intended to try and find the Andromeda Galaxy, but that didn't work out so well. I was hoping I could use the R.A./Dec. coordinates from the astronomy software that came with the telescope, but unfortunately the R.A./Dec. dials on the telescope don't seem to bear any relation to the coordinates of whatever the scope is pointing at. Very frustrating. I'll have to either figure out how to get the dials to function properly (this probably involves aligning the telescope in a manner that's more complicated than what I've been doing) or use other means, perhaps the Space Navigator that my in-laws got me for Christmas.

So, I didn't see any galaxies. I did manage to get the scope pointed at the Pleides, and saw what appeared to be a nebula within the cluster. At first I thought it may just have been some extra glow from a particularly bright star through the damp air, but the edges seemed to be well-defined, and I didn't see any similar glows on other bright stars (including Sirius, the brightest damn star in the sky, which was hanging low in the south). It turns out, according to the Internet, that what I saw was not a nebula, but reflection nebulosity caused by the light from the star passing through interstellar dust. Neat!

Finally, I gave Mars another shot. It's still just a small red dot, and it was even fainter this evening because it was right near the Moon, and the light from the Moon was washing out the glow of the planet. I'm kind of done with Mars for this year. According to my astro software, however, Saturn will be showing up in the east in a few hours. I may stay up for that.


The weather in the Bay Area this week was 100% pure ass, at least from a backyard astronomer's perspective (it was great if you like sitting inside, drinking beer, not wearing pants, and watching your cats get freaked out by thunder and lightning). So, I don't have any stargazing adventures to report this week, so instead I'll provide a rant about Right Ascension / Declination telescope navigation.

Back when I was studying physics in college, one of the (many, many) things I had trouble with was the polar coordinate system, or any coordinate system other than Cartesian coordinates. Don't ask me why, my brain just found it more intuitive to work in rectangular space. Any situation requiring the use of spherical or cylindrical coordinates basically meant that I was starting at less than zero.

I seem to be encountering the same mental block when it comes to using the mount on the new telescope, which operates on the Right Ascension/Declination (R.A./Dec.) coordinate system. My previous, grossly malfunctioning telescope, used the Altitude-Azimuth (Alt.-Az.) coordinate system. I realize that neither of these systems is Cartesian, but to my feeble, uninitiated mind, Alt.-Az. is a lot easier to use.

Making adjustments on the Alt.-Az. mount was very simple. The telescope swiveled on the horizontal plane (the azimuth), and on the vertical plane (the altitude). It was therefore relatively simple to get the telescope pointing in a direction you wanted it to, since the movement was limited to up-down and left-right from the observer's perspective.

The R.A./Dec. system is much more complicated, mainly because of the declination. Right ascension functions similarly to azimuth, and is essentially a rotation along the horizontal plane (though not really, because the whole telescope is pointed slightly up depending on your latitude). The declination, rather than being a simple rotation along the vertical plane, is more like turning a doorknob. Adjustments in declination make the front of the telescope move in a circular motion.

Now, I'm sure the R.A./Dec. coordinate system has its advantages, particularly among astronomical purists who might prefer a coordinate system tied to the immovable heavens rather than the capricious Earth. I can accept that philosophical preference, and am even willing to entertain the notion that R.A./Dec. coordinates are easier to use. Only here's the thing. When you have an actual backyard telescope, the coordinate system is less important than being able to move the telescope in an intuitive manner. The R.A. and Dec. dials on the telescope aren't that granular -- the tick marks are in multiples of two. So when I look up the coordinates -- in either system -- of something I want to look at, the best I can do with the dials is get the scope pointed in the general neighborhood and then make adjustments visually. This is a lot easier to do with a scope that moves left-right/up-down than left-right/clockwise-counterclockwise.

So, to conclude, despite my fascination with the curvature of space, in my day to day existence I like to pretend I live in a rectangular world. At present, my White Whale is the Orion Nebula. If I can find that, R.A./Dec. be damned, I'll be satisfied with the new scope.

Jiggly Mars


Tuesday night was very, shall we say, moist, but I could still see quite a few stars and Mars was shining like it was about to fall out of the sky so I decided to take the scope out for another whirl. I still haven't aligned the viewfinder, but I wanted to see if I could figure out how to use the freaky R.A./Dec. coordinate system on the mount. More about that in another post.

I was able to find Mars with the telescope by setting the appropriate (or close enough) declination and then free-adjusting the right ascension until I saw an orange glare coming from just outside the field of vision. I centered Mars in the eyepiece, and it looked like a tiny orange dot. I set the R.A. and Dec. clamps and got out my Barlow lens and the second eyepiece the guy at the telescope store insisted I have, which together should have increased the magnification of Mars considerably.

The first thing I noticed is that, when you're observing a very small area of the sky through a telescope, things move fast. In the time it took me to get the other lenses ready, Mars had drifted out of view. This wasn't a big deal, since I was able to find it again using the fine adjustment knobs, but it was still neat to see.

What was less neat was the view of Mars through the more powerful optical set up. The image did appear bigger, but it was also incurably blurry. No amount of fiddling with the focus knob seemed to help, since the orange dot was moving in steady, jiggly circles, apparently caused by some sort of vibration in the ground. I'm not sure how to cure this, since I'd imagine the stupid tripod would correct for that.

Hopefully big-gun optics will work better on larger objects, like Jupiter and Saturn, but we'll have to wait and see.

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This page is an archive of entries from January 2008 listed from newest to oldest.

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