Sudden cold front temperature change

A fantastic wind shift and cold front passage last night dropped temperatures by twenty degrees Fahrenheit in the course of a few minutes. As is common here, the cold front used the lake as an expressway south to accelerate and end an otherwise warm and humid Memorial Day. As experienced by me, a quiet warm night suddenly grew loud as the trees shook, then a blast of cold air blew through my open windows in a gust. Another account.

This data is from the Ryerson weather station.
--Timestamp--- Temp Humid Dewpt Wind HiWind WindDir
20080526 19:30 80.6 57 63.9 8 18 247
20080526 20:00 79.8 58 63.7 6 15 247
20080526 20:30 79.0 61 64.4 5 13 270
20080526 21:00 78.2 63 64.6 4 13 247
20080526 21:30 77.6 66 65.3 5 11 247
20080526 22:00 76.8 67 65.0 5 11 247
20080526 22:30 76.1 69 65.2 4 11 270
20080526 23:00 54.3 73 45.8 10 35 270
20080526 23:30 51.9 78 45.3 18 41 0
20080526 24:00 48.8 82 43.6 18 33 0


One of the few storms that popped up on the warm side earlier that evening
Is this cloud from the cold air bumping the warm humid air up and out of the way?

Even more awesome Mars images?

You've seen the amazing image of Phoenix descending in the Martian atmosphere as taken from MRO's HiRISE. (As Emily Lakdawalla puts it: "OMG!! Parachute!!!! Photo !!!!!" You might have seen the first false-color images. But now there is a rumor about another HiRISE image of Phoenix while it was still descending in front of Heimdall Crater.

Is this that image? Not spectacular enough after the first image.

One hour to Phoenix Mars Landing

One hour to go.

The newest supernova in the Milky Way

The last supernova in the galaxy was Kepler's star of 1604 in Ophiuchus. Or was it? You'd expect a supernova in a barred spiral of our size every 50-100 years. We haven't seen any, and it's because of that pesky dust in the way, blocking our optical view. But it looks like follow-up x-ray work from Chandra has found evidence of a 150-year old supernova in Sagittarius!


X-rays in orange, radio in blue. Reminds me of the firefox logo.

It looks like the impetus for revisiting the radio work in 1985 was that the x-rays detected by Chandra were significantly outside the 1985 radio contours implying rapid expansion. See the paper here.

P.S. Tip to General Carlessness and Bad Astronomer

Adventures in large format digital photography: part 5

I got the camera working again, kinda of. It doesn't work with TWAIN enabled stuff. It will work just fine using Vuescan on Windows and XSane on Ubuntu. Exposures are weird with Vuescan--I seemingly lost 3 stops of speed with it.

I also dremeled open the highly vignetting slot that previously limited the images to that narrow vertical view. I can now scan 7x11 inches. (Somehow I lost an inch and a half--the sensor is dead below 7 inches). There is also a band of vignetting and/or low sensitivity right across the central-top of the frame.

Kaguya: Color on the Moon

I was perusing (as best as possible without reading Japanese) the currently released images of the Moon from the Japanese spacecraft Kaguya when I encountered this one. You nearly forget all the images are in color when all you are looking at is the nearly monochrome Moon.

Click to enlarge to HDTV resolution

The bad idea of a gas tax holiday

Tom Friedman points out the obvious stupidity of McCain's and Clinton's idea of a gas tax holiday for the summer.

Broke the camera

In my attempt to remove the prominent vignetting which restricts the scanned area to 5x8 inches, I broke the camera. This was to be expected, as it has happened every time I try to do it (or at least soon thereafter). I can only hope the problem is a physical gearing issue, which means I might be able to fix it. And I hope it does, as I'd love to take it out west and south and other places...

Rockefeller Chapel, Reynolds Club, and Flowers

The light was rapidly falling last evening and this was my last image, with a full open aperture, but it was still underexposed by about a stop. Expressed in other terms, a film camera with 100ASA film would expose for this for about one second at f/8. Autoleveled and hue adjusted in photoshop. See the original here. This also was the first outing of the camera with a coat of black paint in the interior, an additional baffle on the top to handle light when doing macro work, and I added a shoulder strap with some eyelets (one broke on the trip). Remind me to stick some teflon strips or wax the bottom of the inner box--it's getting too hard to move to focus.


A color image, underexposed. The lightest of breezes moved the daffodils a touch between exposures. The flowers were just over 4 feet away.

CF Torchiere replacement

Compact Fluorescents are all hot right now. And it's Earth Week.

I bought a floor lamp from Home Depot that used a single standard bulb and didn't have any fancy dimmer system: it just had a hi/lo switch (I'm still not sure what it does with it--the CFLs flicker on the low setting, so I quickly turn the lamp to high when flipping the switch. It could be a simple rectifier to provide 50% of the power). I then bought three lamp socket splitters. These screw into a standard lamp socket and provide two sockets. So, with three splitters, a single socket becomes four. This is OK because the CFLs use so much less power--with four of them, I'm only using 100W, and the floor lamp suggests using a 150W standard bulb. The sockets themselves are rated higher, so I think the 150W max is for thermal/fire issues (high wattage bulbs can start fires if drapery or other flammables fall on them).



Taking pictures of lighting fixtures is hard--either the fixture looks dim and the room dark, or the fixture is overexposed.



If you think the color temperature is off, you can adjust by using different color CF bulbs. Here was an experiment with a 2:1 warm:daylight ratio.


an even ratio between warm and daylight. This was too cool for evening use. The color is way exaggerated here--the yellow bulbs are nearly white to the eye.


The color of the photographs is too strong--your eye does not see such strong color in the fixture.

In any case, I made this fixture 100% n:vision 100W soft white bulbs, and use it all the time. I have a second fixture where I replaced the dimmer switch with a standard push switch (it's tough to find a switch that fits in small diameter torchieres) so I could use compact fluorescents in it. I put 3 GE 100W daylight bulbs in the latter fixture and use it only during the day.

Now the caveat: the splitters stick the bulbs higher than where an incandescent would be in the fixture. Ideally the rim of the lamp shade would be a touch higher, but I've yet experimented with the right material to make one. Doing so would improve the fixture and reduce glare from it.

The end result is I've increased the lighting in my otherwise dark apartment (north facing windows on the first floor) and decreased my lighting energy usage by 50%, even more on average since I don't use the second fixture at night. I'm already being paid back on my electricity bill: some $10 a month less.

Weather on campus

The Ryerson Astronomical Society got SG funding for a weather station on campus, to get accurate weather data (which is really important in the spring with lake breezes freezing the lakefront while Midway is warm). We finally overcame all obstacles last night and have the station live at http://sagan.uchicago.edu/. I believe we have other delivery vectors to set up, so it can be seen at the Reynold's Club TV screen and such.

Adventures in Large Format Digital Photography: part 4

Today I mounted an inexpensive IR blocking filter in front of the lens using a cardboard mount. It's ugly, but gets the job done. I did this because after a second outing with the camera the odd tones on vegetation and clothing were getting tiring. It also allows me to make real color images with three separate red green blue scans.


Three separate scans using a 25A red, 47 blue, and a combo X1+Y2 greenish filters. Added together in photoshop and auto-leveled, plus some addition saturation, and some highlight/shadow work.
The green is not a true tricolor green, it's more yellowish. I need to buy the 61 green to get better matching.

Red Shirt Phenomenon

A great way to drive traffic to a site about web site statistics. Don't miss the powerpoint slides.
Analytics according to Captain Kirk

...One of my favorites is an analysis of the Red-Shirt Phenomenon in Star Trek.

What? You don't know about the Red Shirt Phenomenon? Well, as any die-hard Trekkie knows, if you are wearing a red shirt and beam to the planet with Captain Kirk, you're gonna die. That's the common thinking, but I decided to put this to the test. After all, I hadn't seen any definitive proof; it's just what people said. (Remind you of your current web analytics strategy?) So, let's set our phasers on 'stun' and see what we find...

seen via B12 Solipsism

Adventures in Large Format Digital Scanning: Part 3

Click to enlarge any of these to the original size (the first image is actually only 50%).


An early image with the prototype cardboard camera. This image was auto-leveled, sharpened, and hue altered to attempt to match the original color out of the camera.


When outdoors with a small aperture all the dust on the scanner glass becomes visible, as seen in this and all further images in this post. I ended up cleaning it after this first trip outdoors.


You can heavily sharpen the images out of the camera: this one is at 169%. I am still experimenting with basic things like focusing and apertures, so final sharpening levels are way in the future.


I made a second scan of Lui at 1200dpi, cropped, and cropped some more in post-processing. It looks soft on the original and I think 1200dpi might be interpolated (although Canon says 1200x2400dpi). It's also possible the focus was off.

The new cheap subnotebook race

More gadget blogs need this sort of writing. We are using several Eee PCs here as dumb terminals for various headless servers and they work great. In some cases they replaced 15 year old Toshiba laptops that until now had no modern replacements.

A few months ago, a Sony executive, asked what he thought of the success of the Asus Eee bargain sub-notebook, leaned back in his chair, sucked on his cigar and smugly denounced the pursuit of cute, tiny, low-cost laptops as "a race to the bottom." Then, turning dangerous, he leapt like a panther across the desk, tackled his inquisitor and plunged the smoldering ember of his cigar through the vitreous of his interviewer's eye.

Boing Boing Gadgets: Dell Joins Asus, HP In "Race To The Bottom" with Budget Sub-Notebook