Whorls

On my last observing run, we winded and clouded out. However, looking at the infrared water vapour pages at NOAA, I saw a beautiful line of vortices spinning out between two fronts of air.


NOAA keep all the imagery public for 30 days, so use a script to pull the images over and stitch them together with mplayer to produce an animated GIF.


# grab all the data for this night with the whorls in them
for i in q -w 0 23 do wget http://www.goes-arch.noaa.gov/WCWV08145${i}00.GIF;done
for i in q -w 0 23 do wget http://www.goes-arch.noaa.gov/WCWV08145${i}30.GIF;done
for i in *.GIF; do c=`echo $i | tr '[:upper:]' '[:lower:]'`; mv $i $c; done

for f in *gif ; do convert -quality 100 $f `basename $f gif`jpg; done

mencoder "mf://wcwv*.jpg" -mf fps=10 -o test.avi -ovc lavc -lavcopts vcodec=msmpeg4v2:vbitrate=800


Big Ideas (using a ZX Spectrum)

This video actually made me tear up a little bit. The nostalgia! The genius! He even used a "WH Smiths" computer cassette tape, which all parents were conned into buying for their Speccy laden kids at Christmas!

Kudos to Tim P. for finding the link.


Big Ideas (don't get any) from James Houston on Vimeo.

Arseilles and Airports

Well, that was a bad experience.

I went to a work conference in Marseilles for a week, and I am glad to be back in the country. To be fair, these particular conferences are week long affairs that result in burnout in three or four days, but this one was compounded by the, um, facilities that were laid on. To add insult to injury, we had paid 600 Euros with the punitive exchange rate of about $1.6 to 1 Euro for this conference, and what do we get?

One the first day, we got:

No air conditioning. In Marseilles sweaty summer heat.

Half the number of chairs for the number of people that attended.

Four of the talk rooms were in fact one single space divided by chipboard dividers. Yes, we got the triple whammy of hearing someone else's talk, not being able to see the slides because there was a wall of glass windows with daylight streaming in, and no microphones for fear of drowning out the other conversation.

Standing at the back of the rooms reminded me of a Merchant Ivory film set in the deep south - half the people were fanning themselves with their programs and the men generated minature armpit lakes of sweat in their buttondown shirts.

Oh! And they didn't have any supplies of water - no fountains, no jugs of tap water, nothing at all. I think I made five new friends when I looked under a cloth covered table, stole a bottle of Perrier water (that was scheduled for us in the afternoon, remember) and poured out five glasses of cold water. There was a minor stampede as people raced over and drank thirstily, and then I was told off by a French waiter for drinking unallocated water. They would have made a mint if they had had a stall selling bottles...

So - Charles de Gaulle airport. Essentially, don't go there. At all. If you can help it. For although it is pretty to be in, they have only two toilets in the E side of the building - apparently beautiful people don't need the toilet at all. And also, you cannot move the artfully designed chairs from their appointed spots, as THAT'S WHERE THEY HAVE BEEN BOLTED TO THE FLOOR. Do Not Disturb The Sexy, People.

Technical Support

The creator of the Pringles can gets buried in a Pringles can.

Don't worry, he was dead at the time....

Saturday Night, and Sunday Night

I went observing at the MMTO for four nights last week, just in time for an unusual low system to come down and give SNOW on the mountain in May. In Arizona.

To add annoyance to irritation, we were clear on saturday and sunday night, but of course.... the wind was too high. The chart from the automated weather station is shown above.

The Zamboniscope

It's a bad sign when you can make Roger Angel laugh out loud at your idea.

In a conversation with James Lloyd from Cornell at the Spirit of Lyot conference in 2007, he'd mentioned a novel way of making a space-based telescope using an old idea called a "luneberg lens". The lens is a sphere of matter, with a certain monotonic gradient of refractive index that varies only with radius, i.e. n=n(r). If you place a camera on the surface of the sphere and look back through the center of the bubble, you form an image that is free of spherical aberration and many other low order terms.

Lloyd's idea was with trying with a gaseous diffuser - initially, the gas flies off at the speed of sound determined by the temperature of the gas, but if you constantly replenish it from a compact source, maybe you could attain a steady state and have a large, very long focal length lens floating in space. Thinking further though, there is a simple case which shows that this doesn't work - when we look at distant stars passing behind the atmosphere of nearby planets, very little refraction of the the star is observed. So, even with approximately 1 STP of atmosphere, the focal length of such a system is ludicrously large.

Okay, so that doesn't work.

But.... what about a liquid or a solid?

I vaguely recalled that there is an under ice experiment in Antarctica that uses strings of photomultipliers, melted and subsequently refrozen into place in the antarctic ice many hundred of meters far below. Surely there was some measurement of the transmission coefficient of this ice?

Sure enough, there was! And the numbers in the paper blew me away - the mean free path for visible/blue light is about 200 meters - yes, that's right, the ice is so free of scattering microbubbles that you can see for two football pitch lengths.

Adding to this, it turns out that this is several times clearer than any ice made in a laboratory. The purest ice in the world appears to be about 1000m below the surface of Antarctica.

So, if you can manufacture a sphere of pure ice, which is then doped with a chemical that provides the index of refraction change in accordance with the Luneburg formula, you're good to go.

How big a lens can you build? Well, since we are in the realm of fantasy here, I thought I'd be conservative and go for 500m in diameter. After a quick bit of algebra demonstrated to me that the optimal size for an Ice lens is on the order of the absorption length (the exponent in the absorption quickly clobbers the effective surface area of the lens with increasing diameter), I also came up with a way to do the metrology. Get your sphere to within 1cm of the ideal sphere, and then use a reflective ball bearing in the center to act as a reference mirror, and then have machines that trundle along on the surface of the lens, peering down through a liquefied section of the ice that is melted by a surrounding hot plate.

Hmm, a machine that melts rough ice into a smooth surface. Where have I seen those before? Ah, at the ice hockey games!

Yes, I've invented the Zamboniscope.

No wonder Roger laughed at me.