Monolith149 Daily

The Perseid meteor shower will be happening Tuesday night 11 Aug and Wednesday night 12 Aug. The actual, theoretical shower peak is Wednesday 12 Aug at 14:00 EDT. Conditions aren't ideal since the moon will be a waning gibbous.

Information is here at Sky and Telescope.

Here's a general observing guide at Sky and Telescope.

The main thing is to go outside, in the darkest location possible, lie on the flattest thing you can lie on (lawn chair, adirondack chair, ground) and watch the sky, the whole sky or as much as possible. The shower will be best after midnight or 1:00 or 2:00 in the morning, when we are on the side of the earth encountering the meteors head-on.

Sunday, August 09, 2009

How I Learned to Quite the iPhone and Love Google Voice

RT TechCrunch How I Learned To Quit The iPhone And Love Google Voice http://tcrn.ch/4IFB by @arrington

Saturday, August 08, 2009

Bokodes

Mike sent me this interesting article on Bokodes, an idea from the MIT Media Lab for replacing bar codes. It' s an interesting idea with interesting optics. Their paper is linked to at the site.

Now that I've read the paper, the optical idea is pretty simple. They put a tiny lens in front of their pattern (say, on a product). The lens acts like the objective of a microscope. It focuses light from the code as parallel rays. (I suppose that's actually un-focusing the light!). When you point a camera at this, even from a large distance, it acts like the eyepiece of a microscope and, when focused at infinity, focuses an image of the bokode onto the camera's sensor.

This very long microscope is very sensitive to angle. A focused image is insenstive to distance though the size of the image will vary with distance.

Fascinating!

Wednesday, August 05, 2009

Jupiter Impact Image

This is an excellent image of Jupiter and the impact site by Mike Hood at Spaceweather.com.

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).

Camel

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

Futurescapes

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.

http://www.youtube.com/watch?v=2kEXMCQw6VY

http://www.youtube.com/watch?v=5vytMN7RBlE