What I Learned Today: Ack and Ephemerides
Been so busy there’s barely been any time to think about blogging. Today’s edition of What I Learned Today covers two totally separate topics. The first is:
Ack
Ack you say?! Yes. ack. Ack is a command line utility that searches through files for patterns of text. It’s like grep except…it’s more friendly, has some options turned on by default, as far as I can tell its faster too. Oh, and as the ack page points out, its one character shorter than grep. Plenty instructions over there on how to get it installed. I had macports running already to i just:
?>sudo port install p5-app-ack
and I was done in a minute.
Ephemerides
Right. So as some of you might know I’ve been working on this android app for my G1 that displays stars and constellations given the current date, time of day and your geographic location on Earth. I’ve gotten to the point where the stars are showing up, the constellation lines are being drawn, and shit generally looks correct. And then one of my co-workers of course says, “Hey, where’s the moon?”. At which point I throw miniature beach ball at him and say, fuck, I don’t know.
The star data had been pretty straight forward, given out (after some searching) with a RA and Declination that just worked (once you did some gnarly calculations). Data for planets and other objects in our solar sytem (ahem, Luna you ass) however was much harder to come by. I’d been looking on and off for the last week, and just couldn’t find the right information on how to calculate a RA and Declination I could use for the moon. Until today. I needed an Ephemeris. Which is just a fancy way of saying data table. Now if only someone could tell me how to calculate an Ephemeris, eh, maybe I don’t want to get into it. That’s OK, go fucking NASA! They’ll do it for you. Awesome, exactly what I needed. Mad props to ‘jim m’ on the astronomyforum.net moon forum for the tip.
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