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.

About this Entry

This page contains a single entry by hb published on January 13, 2008 9:12 PM.

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