Saturday, March 29, 2008

near infrared lights

When I need good near-infrared lighting, I turn to the broadband sources called the Sun and incandescents. They are the closest thing to a blackbody we see on a regular basis.

I presumed on this post that I was seeing an intense sodium line from high-pressure sodium lighting while taking daytime near-IR images. What I didn't realize while speculating at that point was that every high-intensity discharge light has a very hot envelope--for high-pressure sodium, a bulb of aluminum oxide (all jokes about transparent aluminum aside, of course). For metal halide and mercury vapor it's usually fused quartz, but sometimes it's the above alumina or sapphire. The tough requirements of dealing with a circa 3500K corrosive plasma dictate the choice of material. Have you ever seen a cycling HPS streetlight? As soon as the arc extinguishes you can see the pure blackbody glow of the very hot bulb window which is at or just below 1200K. That's what I'm detecting in the infrared shots--any HID light that is on is a great IR source. See this shot of the Chicago Theological Union / Oriental Institute or this one on the central quad of the University of Chicago -- the metal halide lights are on in the early evening with sunlight still streaming in. (Don't get me started on energy decisions here). Or here.

Or this HPS streetlight here at Hull Gate.

Compare that with fluorescents: they on the other hand are very poor in near-IR light, as expected from an efficiency standpoint--visible light is what you want in an efficient system. (The HID lights are highly efficient despite emitting copious near-IR light because the arc is incredibly bright and efficient in the visible. But you can't get such efficiencies in a low wattage bulb).
You can see fluorescents glowing a bit in this test focus shot of the first floor of the Reg:

Around the edges of the room are fluorescents, dimly adding some near-IR that is red or very near red. Notice that the ends of the fluorescent tubes are purple: this is further into the IR, and what you're seeing is the thermal glow of the little filaments that heat up and emit electrons. When I need near-IR indoors, I use old-fashioned tungsten: a single 60W incandescent bulb will outlight a room of fluorescents.

The perfect match: Southern California and Solar Energy

This is great news: Southern California Edison is going to build 250MW of distributed photovoltaic solar energy across Riverside and San Bernardino counties on top of large commercial buildings. These are inland valleys that get little marine fog and lots and lots of sun. The power company will own the panels and sell the power back to the commercial sites that host the panels, providing distributed power. It helps solve the great bottleneck of transmission between the power sources in northern California and the heavy A/C users in the south. The only caveat is that the inland valleys are also generally the smoggiest places in L.A. Improving the air quality will also improve the energy yield, but generally the smog is from automotive sources instead of coal plants--the coal plants that Southern California Edison use are all further east, polluting the desert.

Let's expand this to all the sunny cities of the desert: Las Vegas, Phoenix, Tucson, Albquerque, El Paso, and yes, even San Diego and Los Angeles. Let's even just start with solar water heating.

Tuesday, March 25, 2008

See 3 satellites in the same orbit

As Emily at the Planetary Society Blog points out, there are some decent opportunities to spot three spacecraft in nearly the same orbit right now: The ISS, the Space Shuttle, and the ESA's cargo craft "The Jules Verne". Tomorrow's evening pass is best for Chicago, but it will likely be cloudy, so tonight's low pass might be your best chance to see them. At 8:32 in the SSW the Jules Verne will first be visible, passing into the Earth's shadow directly south at 25 degrees elevation at 8:34. Then the ISS and Shuttle will show up at 8:36:50PM and pass into the Earth's shadow at 8:38PM. Details at Heavens-Above.

Wednesday, March 19, 2008

Bright Gamma Ray Burst

Last night there was a particularly bright gamma ray burst (080319B) located in Bootes that was perfectly located for a number of observatories to go after. An camera called "Pi of the Sky" caught the burst and estimated the peak visual brightness at magnitude 5.7, an amazing level for an object that, when spectra were taken of the fading remnant, is nearly 7.7 billion light years away, at a redshift of 0.937. In one of those coincidences there were 4, count them, 4 GRBs yesterday.
See an animation of the burst from Chile here.

I have a link to the field in the local copy of SDSS here.

Friday, March 14, 2008

Chicago Light Pollution article in Chicago Wilderness

An article about light pollution, focusing on the biological effects, is in the Spring issue of Chicago Wilderness. The article was inpsired by Homer Glen's recent passage of a light ordinance with work by Debra Norvil. Even on a clear moonless night, the integrated flux of light pollution exceeds the light of a full moon at Batavia, in the far western suburbs; it's much worse the closer to Chicago you get. In most of the metropolitan area the light pollution is bright enough to prevent your eyes from fully adapting to the existing light with your rods, making ironically everything appear dimmer.

Thursday, March 13, 2008

Flying over Colorado in the near infrared

Click to enlarge

Simply putting a double layer of fully-exposed color negative over a Canon A540 revealed it does have some decent near-IR leakage. Exposures were deliberately underexposed at 1/3 second to prevent image shake. I used some auto-leveling in Photoshop and faded it back a little.

You can see a number of interesting details in the image.

The first is the darkness of the sky above the horizon. Anyone from the old photography days with a red filter and black and white film is familiar with this effect. The blue sky is caused from Rayleigh scattering of photons by the molecules of air, and it's dependent on the inverse fourth power of the wavelength of light. So, blue photons of 450nm scatter 16 times more intensely than near-infrared light of 900nm. Right at the horizon the only scattering is visible in the red channel, which from previous posts we know is the nearest of the near-IR (i.e., just past 750nm). In the green there is no scattering---just a solid ball of earth with no haze. Like a planet with no atmosphere.

Expanding further on the RGB channels: the red is clearly a tail effect of the red filter--so we know the output is or around 700-750nm. It may have an additional output somewhere higher up if the coloring fades away in the IR. The blue should have a passband around 900nm, given that most bandpass filters will also pass double their wavelength (450nm being blue). Green would, if the doubling held, pass 1000nm, i.e. 1 micron, but at that point most CCDs made of silicon begin to really drop out and to get decent response you'd need an optically thick chip (as light absorption varies in depth in silicon in proportion to photon energy. See the Foveon chips for a practical use of this). And this seems to match the intensity of each channel: Red and Blue dominate, making a raw image very purple out of the camera. Green is always the weakest channel. It may either be passing generic IR from a weak filter or from the color negative filter.

I assume the clouds and the snow-covered peaks (right-center) reflect all wavelengths equally. Assuming that, the ground appears to reflect the lower-wavelength (i.e. deeper into the IR) IR better than the near-IR wavelengths.

The ground itself has some real variations in IR reflectivity, although it's difficult to see clearly: far-right center shows a redder response on a slope. I'd love to correlate some near-IR curves to some common mineral types. I do need to calibrate the wavelength response of the cameras. This isn't the image to do it with and I have some better ones with simultaneous visible light images.

P.S. The curvature of the horizon is just from the camera lens, not the real curvature of the earth.

Monday, March 10, 2008

You should be reading Systemic

Systemic is a blog by Greg Laughlin at UC Santa Cruz about exoplanetary systems--the explosive new field with nearly 300 planets detected to date. The latest post is about the terrestrial analog of the island of Hawaii as Mars.

The landscape here resembles nothing so much as a habitable, terraformed Mars. Hardened ropes of lava run down to the water’s edge:

In the pre-dawn light this morning, the air was totally silent, and it was easy to imagine that I was actually on Mars, before the water was gone, when a Northern hemispheric ocean lapped up against the lava of the lowermost slopes of Elysium Mons:

Wednesday, March 05, 2008

Southwest solar meets the New York Times

Turning Glare into Watts.


Often in desert construction the entire lot is bulldozed for convenience and it doesn't have to be. This applies to one acre lots (from personal experience) to larger plots as mentioned. The compressed surface often only allows the invasive non-native Russian thistle (aka tumbleweed) to grow. I've never seen the dominant native vegetation in the Mojave, the creosote bush, grow back in disturbed plots.

The Push for Imported Drugs

There was a bit of a dust-up in the prescription drug industry a few years ago: because of the high cost of many drugs in the United States, many seniors and others with high pharmacy costs were physically purchasing the same drugs in Canada or Mexico and taking them home with them. Then the obvious follow-up was: Why not just have the pharmacy mail them to you? And the answer was it was illegal under current US law. Then the drug industry in a major campaign said imported drugs wouldn't be safe because they weren't under FDA supervision, despite the fact that many of the drugs in the US were actually made in these same factories and imported by the drug makers. And various attempts to legalize importation from certain countries were tabled.

The FDA said in 2002

Drugs sold in the United States also must have proper labeling that conforms with the FDA's requirements, and must be made in accordance with good manufacturing practices.

As part of the FDA's high standards, drugs can only be manufactured at plants registered with the agency, whether those facilities are domestic or foreign. If a foreign firm is listed as a manufacturer or supplier of a drug's ingredient on a new drug application, the FDA generally travels to that site to inspect it.

After the FDA approves a drug, manufacturers still are subject to FDA inspections and must continue to comply with good manufacturing practices. "With an unapproved drug, you can't be sure that it has been shipped, handled, and stored under conditions that meet U.S. requirements," McCallion says.

Now, we learn that heparin manufactured by Baxter is actually created with pigs from China with incredibly questionable processes--buying random pig's intestines from unknown city farms. Over a dozen deaths, and potentially 400 serious reactions have been linked to the failure of the FDA and the drug industry to maintain quality control.

Is this the quality we were supposed to get from a forced domestic drug industry? Is this what happens with a neutered federal watchdog administration?

Tuesday, March 04, 2008

Geologists and risk: field-work

A coincidental occurrence today: A co-worker sent along a harrowing tale of Bill Menke, a seismologist, taking a truck down the 900ft deep caldera wall of Grimsvatn; and a discussion of some death-defying by geologists in the field. Don't miss the rockfall heading your way photos here.

I've found over the years that slopes aren't usually as impossible as they appear, and you'd be surprised at how you can climb and descend things you didn't think possible--it just takes time and effort. I did more dangerous things growing up in Boy Scouts and Explorers than in geology field courses.

And if you want some reading in which a man gets it right, nearly every time, read Bill's blog writings. Especially Cornucopians and Conservation