Thursday, July 30, 2009

Dixie Dregs, Steve Morse and What If

I just realized that the below piece by Camel, “Ice”, reminds me of “Night Meets Light” by the Dixie Dregs, performed here by the Steve Morse band.

(And you have to watch the following guitar solo).


Also I guess I never posted that, also while listening to Slacker, I heard Camel for the first time. How did a progressive rock group that goes all they way back to the 1971, apparently with quite a bit of success, get past me?!

Roy Buchanan

While listening to the Jeff Beck channel on Slacker yesterday I discovered Roy Buchanan. I don't remember if I knew of him before.

Solar System in Gainesville

For a while I've wanted to go see the Millenium Project of the North Georgia Astronomers which is a scale model of the solar system. Yesterday, we were in Gainesville and I manged to find the Neptune marker.

The planet body sizes and their distances from each other are to scale in this model. The sun is a sphere on the downtown square. Of course most of the inner solar system is located there as well.

Tuesday, July 28, 2009

Star Chart Software: Cartes du Ciel

Question: What good start chart software is out there?

An answer: Cartes du Ciel.

It covers all of the basics. You can set the sky for a particular location and time, navigate around, zoom in and out, pick different projections, change the appearance, add and subtract features (like constellation boundaries or the Milky Way), and print charts. You can even control a GOTO telescope with it.

You can change from the colorful star representation to black stars on white (though the dim stars are a bit too small pixel-wise and hard to see). As you zoom in, more stars appear and that feature works well.

A huge collection of deep sky objects are indicated. Most importantly, you can download and add additional catalogues so that you get to a huge number of objects, down to those probably beyond your instrument.

And it's completely free.

The first thing I wish was different is that the program runs on Windows only. That's a disadvantage which I think will grow over time.

The next thing I missed is a feature of other similar programs: when you zoom into a deep sky object, the symbol turns into an actual image of the object so you can see what it looks like (and zoom into the image further). Yeah, this isn't really a property of star charts, but just something that I find I actually expect. I think you may be able to add this to the program yourself, but I'm not sure.

However, if you want that feature, just use Google Sky. Google Sky doesn't work great as a replacement for star charts (IMHO), but it's fun to look at the pictures.

So, I think Cartes du Ciel can act as a replacement for my SC01 and SC02 Sky Publishing charts, Norton's, Tiron 2000.0 or Becvar, and even Uranometria. You can either print ad hoc charts (I haven't tried this, though) or take a laptop to the telescope.

Monday, July 27, 2009

Apollo 11 Source Code

To commemorate [the Apollo 11 moon landing] the Command Module code (Comanche054) and Lunar Module code (Luminary099) have been transcribed from scanned images to run on yaAGC…

Star Image Out of Focus for Collimation

Here's an excellent video of an out of focus star image being used to collimate a telescope.

The diffraction rings and the little dot in the center (not the star!) are all optical effects. This is all light from a single star but everything you see is caused by the telescope optics or atmosphere.

The dark hole in the center is caused by the secondary mirror obstruction. The whole image is the light filling the aperture of the telescope.

The shimmering and bouncing of light is all atmospheric seeing effects.

The fact that the central hole and the rings are all concentric show that the telescope is well-collimated.

Seeing the Invisible

Wow, these shadowgrams in the New York Times are amazing! They were made by Gary Settles, director of the gas dynamics laboratory at Penn State.

I really like picture 3 of the AK-47 shooting a bullet. The bullet is supersonic and has a nice double-shock cone along with a little trail of turbulance. It's clearly outrunning the spherical shockwave from the main explosion from the gun muzzle. It's also extremely interesting that there is no sound or anything else coming from any other part of the gun than the muzzle.

There's also that dark puff of gas that's moving very fast out in front, leaving it's own cone-shaped trail of turbulence behind.

I'm curious about the spherical shock wave that's a bit in front of the main spherical shock (they look like circles here of course) but only inside the bullet cone. It joins the front of the double supersonic shock where they intersect.

There's also a faint horizontal line in front of the bullet and along its path. What in the world is that? Is it some artifact from the picture making process?

Picture 4 of a revolver shooting is a great contrast to picture 3. Here the bullet is clearly subsonic, and behind the main shock. There's a shock from the back of the gun as well as from the muzzle. The things that I find fascinating here are (1) how the center of the main muzzle shock comes from in front of the muzzle and (2) how the spherical waves from the back of the gun seem to be retarded by the muzzle explosion. They are pulled back and distorted there.

Note how much comes out of non-muzzle parts of the revolver compared to the AK-47.

All of these photos (except for the last one of the insect) show how senstive light travelling through air is to disturbances. This is one of the main problems that astronomers worry about when using a telescope. Any disturbances in the atmosphere in front of the telescope (all the way to the edge of the atmosphere) and inside the telescope have similar effects. They aren't as pronounced but, then again, the high magnification involved, well, magnifies the effects. Pictures 6 and 7 of the hair dryer and candle, though dealing with unusually hot air, illustrate this well. In both picutres take note of the less extreme turbulence in other parts of the room that's still visible.

Telescope users are plagued by warm air rising from people (in front of the telescope), buildings, warm pavement, and then of course the weather. You can easily see the effects in a very similar way, but live!, if you rack a really bright star like Sirius or Vega out of focus. A hand in front of the telescope will have a smoky pattern rising from it, clearly visible, just like the effects in these pictures.

Addendum: Hah! Well, reading the attached article, Prof. Settles discusses how the images are made with a light source, curved mirror, (lens), and a razor blade. That sounds exactly like a Foucalt tester which is used when grinding and figuring a telescope mirror!

Saturday, July 25, 2009


While looking on Youtube I found this interesting video of futurescapes. I think the superimposed adages could have been omitted, and some are a bit unclear.

Many of the images seem to come from WhiskeySierra Graphics.

Astronomical Seeing

Since I recently did a brief class/talk on telescopes, I was poking around looking for examples of astronomical seeing. Here are a couple of videos I found that serve the purpose. In both, you can pretty clearly see the “underwater” effect of seeing.

Friday, July 24, 2009

Observing (B)log

I've decided to try logging my observing with a blog and Twitter. The blog is at the location shown here and the tweets will be on stargate149.

Tuesday, July 21, 2009

Largest Telescopes

What are the world's largest telescopes (currently)?


Well, it was 40 years ago (actually yesterday) that men first set foot on the moon.

Asteroid Impact on Jupiter

There has apparently been another asteroid impact on Jupiter.

Steve Eve's 1/10 Scale Saturn V Launch

Steve Eve built and launched a 1/10 Saturn V rocket. I'm just as impressed by the parachutes and landing! That's a seriously reusable launch vehicle.



Wednesday, July 15, 2009

Milky Way Rise

This is a beautiful video of the Milky Way rising over the Texas Star Party by William Castleman. One thing is clear: We are sitting on a rotating planet inside a spiral galaxy! (… that has a dusty, active plane!). Oh, and we are near a very bright star, too!

I also suspect that you can see the zodiacal light in the middle frames as that faint triangular band of light extending upward from the horizon, toward the right. Zodiacal light is scattered sunlight from the faint, dusty plane of the solar system and can be seen from very dark skies well after sunset.

Monday, July 13, 2009

Slide Rules and Calculators

I came across this message I had posted in 2007 in another location.

We learned to use slide rules and were required to use them in high school physics (which I took as a junior). Or, it might have been in chemistry which I took as a sophomore. In the physics class, we also had a four-banger calculator at the front of the room that we could use, until someone dropped it. It was large with plasma-segment digits for the display (the big, glowing, orange ones).

We understood well what two- and three-digit precision was. Slide rules also made it pretty easy to understand logarithms. I still think about a slide rule scale when estimating the log of a number from 1 to 10.

My slide rule was a relatively cheap Sterling model, but I was a high school student after all.

When I was a senior, I was given a TI SR-51 calculator as my first calculator. Of course the SR meant ``slide rule.'' It had all of the functions found on a slide-rule and also did hyperbolic trig functions.

The next year, when I was a freshman at Ga Tech, there were still people on campus with slide rules on their belts. Of course, we carried our calculators on our belts, too. The cases had a loop for that purpose.

My roommate, who was an older PhD student, used a slide rule throughout my time at Tech, even in the late 70s. I don't think he actually had a calculator, but I don't remember for sure.

P.S. The SR-51 died before it was two years old and I bought an HP-25 and then upgraded to an HP-25C soon thereafter.

Saturday, July 11, 2009

Chrome OS?!

What's this I hear about Chrome OS?

To me, this is simple. Everyone in my family sits down at the computer or picks up a laptop, logs on and runs Firefox. That's pretty much it. There are only rare exceptions where they do anything else. I don't think anyone plays any games on computers that aren't on-line. The biggest exception to this I know of is some music editing like Garage Band.

I personally only use the browser, Chrome on Windows or Firefox 3, and a terminal program. That's more than 90% of my computer usage. The occasional exceptions are Fritz chess and MS Flight Simulator. At work, I use Firefox and xterm windows. That's it.

For me, if there's a good terminal app that runs inside the browser, then I'm pretty much done.

Thus, it makes perfect sense to shave off everything else and make a system that's only the browser and nothing else. That's all. And at the same time, make it faster and more secure.

This is not going to be a server OS. I'll personally still need Linux boxes for that.

The implications for the corporate desktop are huge. Hopefully everyone is already using on-line email and probably most corporate apps are on-line. If you can get everyone to use on-line office apps for word processing, spreadsheets and persentations, then you're done. Desktop maintenance as a function is gone. Everyone has a Chrome OS system, or something like it. The IT Crowd fix, “Did you turn it off and turn it on again?” will literally become the only solution to a problem except for replacing the computer.

And no, there's no reason you can't do this now with careful paring down of a Linux distribution.

I think the biggest dilemma may come for someone like me. I have this suspicision that Chrome OS may be so much better as a browser, I'll have to choose between booting/running it and regular Ubuntu which I might want for some other purpose. Yes, I know Chrome will run on Linux but I have this idea that the user experience will be different enough to make, uh, a difference.

Saturday, July 04, 2009

Telescopes in National Geographic

Here's a nice article in National Geographic on today's large telesopes by Timothy Ferris.

Friday, July 03, 2009

Ant Megacolony Takes Over the World

It's bad enough that an ant megacolony is taking over the world, but they have surrounded my house and are attacking. Yes, it's the same ants!

Wednesday, July 01, 2009

Project Euler

Project Euler is a fascinating set of problems.