Friday, December 30, 2005
The Gibbous Moon rising over Rockefeller Chapel, taken over 4 years ago from Ryerson.
I took this image with an Olympus E-10. It was a humid but nice evening. What can't be seen are the hordes of gnats flying around nor the thunderstorm to the west. I also took an image of the Sears Tower with a tall thunderstorm behind it, with the idea to use the known distance and height of the tower to determine something about the cloud behind it (although you need one more bit of information about the cloud to figure it out).
Saturday, December 24, 2005
The collection, mainly through electronic means, of vast amounts of personal data is said to invade privacy. But machine collection and processing of data cannot, as such, invade privacy. Because of their volume, the data are first sifted by computers, which search for names, addresses, phone numbers, etc., that may have intelligence value. This initial sifting, far from invading privacy (a computer is not a sentient being), keeps most private data from being read by any intelligence officer.
You can't open up my mail (or e-mail) and look for names, addresses, and phone numbers without violating my privacy. The courts have held that e-mail headers are like pen information on phone calls, but the contents of the message are private. Get that? It doesn't matter what or who in the government opens my private communication, they've opened it and it's a clear violation of the Fourth Amendment.
You've got to have a warrant, mister, with a good reason, signed by a judge (hopefully not Posner), describing exactly what you are looking for and why you think you have sufficient cause. You can't open up everyone's communications fishing for crimes.
P.S. Richard Posner later writes during a chat:
I don't think most people would mind the government's scrutinizing their conversations for information of potential intelligence value if they trusted the government not to misuse the information.
Uhh... yeah, we mind. This fellow probably shouldn't be a judge based on his poor reading of the Constitution. It's not what "most people" would mind, it's whether these things violate the Constitution. And they do.
Wednesday, December 21, 2005
Monday, December 19, 2005
Saturday, December 17, 2005
This is unacceptable.
Agents' visit chills UMass Dartmouth senior
How the DHS is searching Inter-Library Loan requests is unknown, probably through one of the big ILL mediators like OCLC's Illiad.
Academic freedom to read and discuss whatever, to expose yourself to all ideas, including foreign ones, is paramount to a democracy. The DHS is inviting fascism by doing this.
Since I am an employee of an academic library, my employment is dependent on the ability of students and faculty trusting that their choices in what they choose to read is relatively private. We offer the ability to patrons to find out who has a particular book out, but only if they agree to the same reciprocal privileges. It's a tradeoff--I could find out who has checked out a copy of Mao Tse-Tung, but someone else looking for a copy of "Uranium" would know I had it borrowed. But with a secret warrant, the government can know what you have read without any notice to anyone. Unacceptable.
I would encourage anyone concerned about this to obviously complain to your elected officials, but also ask about your local library's policies regarding data retention, and encourage them to clean out the data as appropriate. Is your library's policy written and available to you?
Here is the ALA's Library Bill of Rights.
Thursday, December 08, 2005
Thursday, December 01, 2005
It's completely temporary, and could go down at any time, but the average radiation rate for the last minute in my basement office is available at the link. The long term average for the geiger counter is about 7.6 microrads / hour. If the rate goes up to 30 or so, it's likely I put a small dixie cup of western Michigan beach sand on it (the sand is enriched in monzanite which has a small amount of thorium in it).
UPDATE: Back up and running: http://dwarmstr.blogspot.com/2011/03/geiger-counter-back-up.html
Monday, November 07, 2005
"Constant observation is necessary, for when it erupts, a new name could be added to the most deadly disasters in human history....Nyiragongo!"
Wednesday, November 02, 2005
This image was provided through Los Alamos or Lawrence Livermore National Laboratories; Wikipedia claims it's from LLNL but LANL uses it on a page at their site. The four colors on the right are the +4 valence forming different complexes with different anions.
I edited the image and concatenated the colors together for a palette. It looks like some sort of bad hotel color scheme.
P.S. There is some discussion of the first separation of plutonium here: http://chemcases.com/2003version/nuclear/nc-04.htm
Monday, October 31, 2005
Once again, Minor Planet Mailing List has the scoop. Two ~100km bodies orbiting in the same plane as Charon and at 23rd magnitude found via the Hubble Space Telescope. Good thing we haven't dumped it in the ocean yet.
IAU official announcement
This image from Alan Stern (SwRI), Hal Weaver (JHU APL), Max Mutchler (STScI), Andrew Steffl (SwRI), Bill Merline (SwRI), Marc Buie (Lowell Observatory), John Spencer (SwRI), Eliot Young (SwRI), and Leslie Young (SwRI).
Wednesday, October 26, 2005
Monday, October 24, 2005
Monday, October 17, 2005
"I think there is no longer a debate," he said in an e-mail message to The Times. "Dr. Ortiz acknowledges that Brown's team spotted the object in their archives prior to him.""
Saturday, October 15, 2005
I took this photo over the summer. The Linne statue is on the Midway on the University of Chicago campus and to the eye is covered in a light greenish patina but goes quite dark in the near infrared.
P.S. One thing I forgot to mention is that I changed the hue so that the vegetation is green and the sky is blue. Another one like that is here. Also I corrected the incorrect link to the big Linne image.
Thursday, October 13, 2005
"Oh my god! Tours of reactors without background checks!"
"40kg of highly-enriched weapons-grade uranium in the reactor--without security!"
It might be 40kg, but it's sitting in rods with so highly radioactive nuclides it would kill them in a second. No one could handle it at all, and could never actually process it to get the uranium out.
"Big backpacks on campus--they could be full of books--I mean bombs!"
"Building plans on-line! of buildings on campus!" Wouldn't want students to find where their classes were or anything.
"Two nuclear bombs worth of uranium--to make topazes more blue." Yes, again, completely untouchable uranium.
Yes, journalism students looking like, I don't know, students, got tours of university facilities. God forbid!
Universities are places far removed from the insanity that is the paranoia filled United States of today. They allow for actual learning free from irrational thought.
MIT got boned because ABC drove a moving truck near the containment vessel and then followed the clip with a shot of the Oklahama City Bombing. It's a frickin' containment vessel made of inches thick steel and feet of concrete. It can't be broken.
Did ABC show ANY ANY nuclear engineers on camera? Just the NRC head, who knew how to deal with media--apologize and promise to tighten things up. Ask an engineer about a reactor and learn about the safety features. You can't get bomb material from a reactor without industrial processes. Ask the US Government on the square miles of buildings they used to extract plutonium at Hanford.
Tuesday, October 11, 2005
Sunday, October 09, 2005
"The pump operator's story reflects a spirit of civic responsibility that rallied in humble quarters like these when Hurricane Katrina roared through the Gulf Coast, soon to be followed by Hurricane Rita. At the same time, it illustrates the degree to which the once-solid foundations of that system have become an illusion. For decades now, we have been witnessing the slow, ruthless dismantling of the nation's urban infrastructure. The crumbling levees in New Orleans are only the most conspicuous evidence of this decline: it's evident everywhere, from Amtrak's aging track system to New York's decaying public school buildings.
Rather than confront the causes of that deterioration, we are encouraged to overlook it, lost in a cloud of tourist distractions like casinos, convention centers, spruced-up historic quarters and festival marketplaces.
The inadequacy of that vision has now become glaringly obvious. And the problem cannot simply be repaired with reinforcement bars or dabs of cement. Instead, our decision makers will have to face up to what our cities have become, and why.
The great American cities of the early 20th century were built on the vision of its engineers, not just architects. That spirit can be found in the aqueduct that William Mulholland built in the 1910's, transforming the parched Los Angeles desert into a sprawling urban oasis. And it paved the way for the soaring skylines of Chicago and Manhattan architects."
Sunday, October 02, 2005
The Keck 10m scope can easily beat the resolution of the Hubble Space Telescope when it is using the adaptive optics system, but it only beats Hubble over a very small patch of the sky at a time. It's great for looking at singular near point-source objects.
How does knowing a moon's orbit give you the mass of the parent? Here is what you know: You know the angular distance between the moon and the parent, which gives you the actual distance away from the planet, since you also know the distance to the planet from the Earth. Using Newton's formula of F=G*M1*M2/R^2, and that the apparent centripetal force for the moon is F=M2v^2/R, the two forces are equal, so you get that the velocity is equal to the square root of (G*M1/R).
The period is equal to 2pi*R/v.
So, the period is equal to 2pi*R/(square root of (G * M1/R).
Or you can say the Mass of the planet is equal to 4pi * R^3/G * T2. I think. Okay, I went back and checked some sites, and my derivation looks correct. This site has a good look at it.
Wednesday, September 28, 2005
I took a quick set of shots of Messier 27, a planetary nebula, last night from Ryerson, after fixing a piece of equipment on the telescope. This is 128 images of 15 seconds added together to make a 32 minute equivalent exposure.
Wednesday, September 21, 2005
The drop, the canyon you pass through, is Cajon Pass. It is a critical transportation, infrastructure, and drainage corridor. It is also entirely a creation of the San Andreas Fault.
On your left side as you head towards L.A. are the San Bernardino Mountains. On your right, and more impressive in appearance, are the San Gabriels. They, and some other ranges to the west, constitute the Transverse Ranges, a east-west set of ranges. They are really one mountain range, formed from the compression along a kink in the San Andreas slip-strike fault. The motion of the Pacific plate, normally slipping smoothly, rides hard against the North American Plate at this location, compressing the land up into an unstable, steep, untenable range.
Why there is a usuable (although steep) pass right in the middle of the mountains can't be ascribed to luck--the San Andreas Fault runs NW-SE right through the pass. You can see a diagram of this from here: http://www.laep.org/target/fragile_habitats/images/mtns_calif.gif (The link was down today but it's been up before).
Also, I've annotated a TERRA image of Southern California:
The full image showing the whole region is here:
This is a nice block diagram showing the region from the USGS.
Imagine sliding the left side of the satellite image down and to the right, and now the San Gabriels and San Bernandinos line up.
Not only does the fault create the range, it also slices the range up.
University of Chicago and Hyde Park types will be amused by the roads in the small settlement near the base of the canyon. Google Hybrid link.
Another point of interest is the strongest plume of sediment you can see in the ocean. The Cajon Pass drains through a convoluted path of washes, creeks, and dams to the sea right there. Is some of that silt from the rapidly eroding rocks of the Pass? Absolutely.
I originally started writing this entry in August, trying to start out with a broad comment about how geology completely controls topography. I am amazed at how every geographic and topographic structure can be explained geologically. That approach to the entry didn't work, so instead I wrote about a specific instance. And what's amazing is I am finding these explanations everywhere.
Thursday, September 15, 2005
Michael Brown wrote up his page about the issue here.
Reiner Stoss forwarded Brian Marsden's CCNet post about the issue to the MPML as well; it is available here for the moment.
Jose Luis Ortiz of Sierra Nevada Observatory asked me
to forward his letter.
Hello MPML, I provide you this information which will
go to my webpage in the next days. The detailed timeline
of our find was given to Daniel Green, director of CBAT long
before any controversy. Anyone can ask him and check against
any other timings of events provided by M. Brown. I suppose
that this has been done by the pertinent authorities and
that is why no official request on anything has been sent to
us by the International Astronomical Union (IAU).
Here I will repeat the timeline of events and even expand
The analysis of most of our 2003 survey images had been
postponed several times because they had a different optical
configuration to the current one and many images had problems,
so only this year did we begin processing them.
On Monday July 25th the object is found in some of our
March 2003 triplet images. We do all possible checks to discard
image artefacts being the cause and to make sure it is not a
false positive. We had had false positives in the past so we
were very careful. We realized that the object was very bright
and could be the same one mentioned in a DPS abstract web page.
A regular google internet search on K40506A leads to a public
internet web page with what appears to be coordinates of many
things. This is no hacking or access to private information nor
spying of any sort. Some of the coordinates shown in those pages
are not very far from ours despite the several years difference
so the object could be the same one but we cannot really tell as
we are not dynamicists and we decided to submit the astrometry
to the Minor Planet Center (MPC) because the MPC is to make such
On Wednesday 27th a report with our 3-day 2003 astrometry is
sent to the MPC with the subject "possible new object" as we
were not sure if it could be new or not. MPC reports have a very
short and specific format and are not regular scientific publications.
Astrometry of known or unknown objects is regularly submitted by
many of us to MPC and as I said they are not peer-reviewed
publications and have no references or bibliography sections,
but even if we had that option there was no possible reference to
give as K40506A was nothing standard and it was not even sure that
it was K40506A.
Apparently this report went unnoticed to the MPC and since we did
not get a response, the next day we seek help of OAM people for
precovery (that is, to try to find the object in publicly available
image archives on the internet) as we had no experience on this.
This requires orbital computations for which we do not have expertise.
R. Stoss was particularly helpful as a reputed person in precoveries.
The description of the process is very technical but I reproduce
it here anyway, quoting parts of his own words to the minor planet
The initial orbit based on the three positions from 2003 was a
crap, even retrograde if I remember well, but it was good enough
to find it on NEAT data from few days later. This way the orbit
was improved iteratively, the prediction improved, new frames
found etc. until the NEAT archive was plundered. The next step
then is to go to DSS, until back to POSS I. From all the 1-opp
TNO precoveries I had done so far, this one was a no-brainer.
The object was very bright and the "stepstones" were perfect,
i.e. the frames and plates were perfectly "timed". Thus DSS2
and 1 were plundered and some POSS I non-DSS plates as well and
both NEAT and DSS data submitted.
Additionally, as it was getting dark in Spain and weather was
clear in Mallorca, I opened over internet the 30-cm scope and
started to prepare it for the night, looking We had to start
before the end of nautical twilight because the object would set
behind the shelter soon. We did 30 images of 30s each and stacked
with Astrometrica in sets of 10 images to get three measurements.
Motion could not be seen visually but the numbers showed it moving
and in the right direction. So I decided we should report these
three data points instead of stacking all 30 images to get one
data point. One data point would have been better (better SNR etc.)
but I know the MPC folks and their pretentions
As a result of all of this the provisional designation of the
object was assigned to our 2003 images, but Brown's group received
credit through several means. It is evident that they spotted it
first, but did not report it to the MPC so the provisional
designation came to our images.
We have been studying physical properties of large Trans Neptunian
Objects for several years and have published more than 10 scientific
peer-reviewed papers on them, so we are driven by purely scientific
goals here. We conduct also our own survey since late 2002 in order
to find a few very large TNOs and report them to the astronomical
community as soon as we find and confirm them because we believe that
international scientists working together, collaborating and sharing
resources can boost science progress and do the best possible job.
In other words, our survey is not only to feed our work, but also to
provide the scientific community with objects that can soon be
studied by the international community with all its man and
Jose L. Ortiz
Tuesday, September 13, 2005
Friday, September 09, 2005
Thursday, September 08, 2005
New Scientist has the press release.
Wednesday, September 07, 2005
Tuesday, September 06, 2005
Paul Frame at Oak Ridge has a great site about radioactive consumer products at http://www.orau.org/ptp/collection/consumer%20products/consumer.htm
and see the potassium info page at http://www.orau.org/ptp/collection/consumer%20products/potassiumgeneralinfo.htm
Monday, August 29, 2005
Thursday, August 25, 2005
Salton Sea Algal Bloom -- Warning -- 18MB
Watch for the irrigated fields in the Imperial Valley blink on and off over time in the animation.
Monday, August 15, 2005
Saturday, July 30, 2005
Friday, July 29, 2005
Thursday, July 28, 2005
Their web site
According to our best orbit fit and using regular assumptions on phase angle
correction, the H value es around 0.3. Unfortunately we do not know the
geometric albedo but if below 0.25 (which is the case of all TNOs for which an
albedo has been measured except Pluto), the object would be larger than Pluto.
However, it may well happen that this object is abnormally bright (with a very
high albedo), like Pluto. So, depending on the albedo, this object might be sort
of a Pluto's brother or Pluto's father...
This object is beyond Pluto and almost reachable by most amateurs, which is the
reason why we write here!. It is observable right after sunset for a while at a
reasonable elevation. Maybe some decent science can still come out of your
Time will tell if it is a legitimate huge find. The size/population numbers have always indicated that there should probably be at least one more Pluto-size object out there, and I always believed someone would find it. Early KBO papers after the discovery by Jewitt and Luu of 1992 QB1 discussed the size distribution with Pluto at the top and kept the option open of other big ones.
Saturday, July 23, 2005
Solar Spectroscope design
Digital setting circles on Ryerson telescope
Long-term office radiation -- just finished a long series at work 9.3microRads/hr.
stuff to do
VLF radio on computer
coffee can furnace (finally a place to use those huge aluminum backplanes on hard drives)
light pollution sensor
fabric dyes (coffee, mulberry)
Tuesday, July 19, 2005
Friday, July 08, 2005
The engineers have decided that the principle of "imprecise positioning with a cheap motor, but with feedback", is a better/faster/cheaper approach than "precise positioning, assume the motor goes where commanded". Instead of stepper motors, with their high torque and their ability to hold them at a defined angle, they used standard DC motors, and read what they're doing via optical encoders, both rotary and linear, on the axles they move (aka servos). In the telescope world, most people prefer to use steppers for positioning. http://www.cs.uiowa.edu/~jones/step/ is a full overview of steppers. I got into learning about motors from the king of converting telescopes into computer-controlled monsters: Mel Bartels
You can tell you have a stepper in your hand if the motor has four or more wires going into it. When you turn the shaft of them, they should feel like they move into defined positions as you rotate it.
I've taken apart a number of inkjet printers, starting with old HP Deskjets from 1990. They used encoders and standard motors too, but the printer was designed to last. Canon Bubblejets from the mid-90's used steppers; and I had always assumed all printers would from now on. The HP Deskjets also used a Z80 CPU; I'd always loved that an ancient processor was still being used in embedded stuff. Keith tells me it's a great processor.
In addition to the DC motors I get some encoders, a beautiful aluminum heatsink, and a 1/3Farad backup capacitor. I would have had a huge absorptive sponge too, but it was full of ink.
Thursday, July 07, 2005
Monday, July 04, 2005
Saturday, July 02, 2005
Thursday, June 30, 2005
The Sun is a convenient source of radio waves. You can see this yourself by watching weather radar around sunrise or sunset. Radar works by emitting a very short pulse of microwave radiation. Then it listens for the weak returns for a short time (since a radar beam is line of sight, there is no point is listening for returns past 200 miles or so because of the curvature of the earth, or roughly 1 millisecond). The time it takes to hear the return gives you the "range" or distance to the object that reflected the beam. When the sun is low on the horizon, the radar receiver picks up the radiation as if it were a continuous return, and it's visible on all of the weather radars.
The image is of the radar from St. Louis last night at 8:28 PM CDT. You can see how the weather radar interprets a continuous return as if there were stronger reflectors further out, and how far north the sun is at this time of year near the summer solstice.
Sunday, June 26, 2005
Colin is spending the summer and next year in Santiago, Chile. I pulled up a recent TERRA image of Chile & surrounding areas:
If you have a computer with a lot of memory and a great Internet connection, try this one: http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?2005175/crefl1_143.A2005175145500-2005175150000.250m.jpg
These images were taken on 06/24/05 at 14:55 UTC, about three days ago.
As usual, wikipedia has a link to great canonical satellite image of the city: http://eol.jsc.nasa.gov/sseop/images/city/lowres/ISS004/ISS004-E-6990.JPG
A really high-res image of part of the city is here: http://www.landinfo.com/GalSatIkonosSantiago.htm
Saturday, June 25, 2005
Wednesday, June 15, 2005
Tuesday, June 07, 2005
I always had thought that the bright white appearance of foliage in the near infrared was due to chlorophyll fluorescence--indeed, in a college class on plant structure and function, I recall examining a large beaker filled with chlorophyll dissolved in some alcohol, illuminated with a strong beam of light, that was deep red when viewed to the side.
You can see a spectrum of various vegetation here. Note how strongly plants begin to reflect at 700nm, which is near the far-red limit of vision. (You can see light beyond 800nm, if it's bright enough, but that's another post of OSHA violations and laser regs).
However, this remote sensing page shows that the high albedo of plants in the near infrared is actually just due to the cellular structure of the leaf. Plant structures are essentially transparent in the near-infrared, and the light is efficiently scattered in the air spaces beyond the first layer of cells. This has been compared to the mechanism that causes snow to be so white and reflective for a substance that is made up of transparent pieces. Newer leaves are not as thick and full of air gaps as mature leaves, and so should reflect less. The spongy mesophyll (what a great term, in my opinion), this interior area, allows for proper interchange of gases, and access to it is controlled by the stomata. Here is a (large) photomicrograph of a leaf cross-section: http://koning.ecsu.ctstateu.edu/Plants_Human/images/leafcslabel.jpg
I took most of these photos over a month ago, when Chicago was experiencing spring, so the trees had small leaves. In many cases, the wind is blowing the trees around and ruining the multi-second exposures!
Tuesday, May 31, 2005
This is a split screen image of Yerkes Observatory in the visual and near-infrared. I moved the camera in between images and wasn't planning in advance, but the comparison still works. You can see the pine tree turns white, the blue sky turns very dark, and the tones of the brickwork and dome sheeting subtly change.
Automobile windows, we are all taught, are wonderful examples of the greenhouse effect. Visible light streams in, is absorbed by the car's interior, and converted to heat. The thermal infrared light is then reradiated by the interior but unable to escape the glass, and the car heats up.
Manufacturers are well aware of this fact, and today's cars have a higher glass to surface ratio than older ones. Given this, why aren't we melting the plastics in the car?
We could tint the windows, to reduce the total light into the car, but this is dangerous at night, and is completely impractical for the windshield.
The answer is in the glass itself. Automotive glass contains a special additive to absorb near-infrared light. NIR is worthless to human vision, but can contribute significantly to the heat load of a car. (I can't remember the reference, but I've read it can be 50%).
Here is an image of a car that visually had no tinted windows; indeed, no one can opaque their windshield legally:
A spectral graph of a glass like that is here. (Link used to go to a nice graph but it's missing).
You can see that American currency has some sort of blank stripe code on the back of the new bills: http://www.lib.uchicago.edu/~dean/infrared/slides/IMG_4784.html.
I saw this at here; and then a simple search shows that it is no secret but a great anti-counterfeiting technique: http://www.accubanker.com/support/irmappings.phtml
These need a separate post.
P.S. Here's an image of a Linne statue with a false-color mapping.
My infrared gallery
Bushes in the near-IR
Sunday, May 22, 2005
All of the images were normalized with "Auto Levels" in Photoshop and desaturated to greyscale. The raw images are very purple and underexposed.
The filter material
was color negative film, fully exposed and processed, stacked
up in three. This sandwich is opaque to the eye except for
bright filaments. There is leakage around the sides of the filter when I place it on the camera lens, and since it's just negative film, there are significant reflections between the three pieces, creating a hotspot in the center of the frame.
In the camera, all three channels respond,
although the green is weaker than red and blue. The response
from all three channels must be the residual near-IR leakage
through the color filters, and scenes appear to be the same if
you compare each color channel. With a two layer sandwich you
begin to see more red light come through, and this creates a
neat contrast between near-infrared-red and near infrared:
http://www.lib.uchicago.edu/~dean/blog/ir2-auto.jpg. There is
a normal visual comparison at
The exposures are roughly 1000x longer with the filter in bright sunlight.
In the next post, I'll discuss some interesting details about near-infrared light: plants, automotive windows, and currency.
And split screen comparisons with normal visual images.
Visual Infrared Comparisons
Plants in the near infrared
Linne Statue in the near infrared
IR hosta (or plantain lily)
Tuesday, May 17, 2005
Tuesday, May 03, 2005
Plus, a graph of the transmission of fully exposed and developed color negative film, from recorded by here:
This helps explain how dust removal scanners with ICE work--the film dyes are transparent in the infrared, but dust isn't. An infrared scan of the negative shows a clear negative with only the dust visible. Silver grains in black and white film are uniformly opaque to light and so ICE won't work with it.
Saturday, April 30, 2005
Thursday, April 28, 2005
Wednesday, April 27, 2005
That isn't snow, it's grass.
A clue to what wavelengths we are seeing is the fact that the streetlight happened to be on, and we can see it, and HPS lights emit a very intense 819.3nm and 819.5nm doublet.
Monday, April 25, 2005
These were shot with a near-IR filter over my camera
(a near infrared filter being two pieces of fully exposed color negative film).
If you swap the RGB colors around, you can eventually get something almost, but not quite entirely unlike, normal. http://www.lib.uchicago.edu/~dean/ir2-rgb-bgr.jpg
Some more (post-processing):
From looking at the RGB histograms out of the camera, it appears that the red and blue filters let the most near-IR through. Traditionally this is the case. The red lets very near-IR through, and the blue lets in IR at double the blue wavelength (a 450nm blue filter will let in 900nm IR, e.g.). The blue channel shows the most chlorophyll fluorescence too.
Thursday, April 21, 2005
Visually, you can see this, especially between Mare Serenitatis and Mare Tranquilatis (wow I can't believe I spelled that right the first time). They are the two prominent, quasi-circular touching maria on the left side. The color difference for maria basalts is the difference in composition of TiO2.
Tranquilatis, the bluer one, is very rich in TiO2.
Giguere, Thomas A.; Taylor, G. Jeffrey; Hawke, B. Ray; Lucey, Paul G.
The titanium contents of lunar mare basalts
Meteoritics & Planetary Science, vol. 35, no. 1, pp. 193-200 (2000).
Saturday, April 16, 2005
Friday, April 15, 2005
Saturday, March 19, 2005
Wednesday, March 16, 2005
Friday, March 11, 2005
Nowadays nearly everything is powered via a switching power supply, as opposed to a linear supply. What's the difference? A linear supply uses transformers to convert the AC running at 120 volts and 60Hz into a lower, often 13.8 Volts 60Hz AC. This is then rectified into pulsing DC via a set of diodes and smoothed out with capacitors. It's wasteful--a percentage of the power is lost via heating in the transformers. They have to be very large to keep the 60Hz oscillating magnetic field inside the transformer.
Switching power supplies first convert the AC into a high voltage DC (around 200-300V). Then, the DC is switched quickly on and off at a high frequency, often 50kHz or higher. This is then put into a much much smaller transformer since high frequency transformers can be much much smaller and still be efficient as a big transformer running at a lower frequency. On the other side, power requirements are measured and there is feedback to provide a pulse-width-modulated approach to supply the power needed.
gives a good overview.
Anyways, they are noisy. The world is a very noisy place in the VLF band.
Long ago, my friend John Crocker ran a 1000ft wire down the length of the Midway, stuck a ground rod into the earth, and placed a pair of high-impedance headphones in between. The VLF radio waves are directly converted into audio frequencies.
Read VLF Radio Part 2: Sferics
Wednesday, March 09, 2005
With the detector 2 cm away and 10 samples of 10 seconds each:
Single sheet of paper: 2466
Aluminum (1/16 inch thick): 577
Aluminum and paper: 563
With geiger counter reversed: 80
With geiger counter reversed and Al: 60
From side of geiger counter: 96
From side with Al: 87
Background count was 12.
Then, I did some distance counting.
Distance Count rate
I also measured the rates with the 1/16 inch thick Aluminum sheet in the way--this way, I was hoping for only the photonic component of the radiation, so no air absorption.
Graphs are needed, I know. I just wanted to post something. Everyone else is busy with end of quarter work.
Saturday, March 05, 2005
Wednesday, March 02, 2005
Monday, February 28, 2005
Saturday, February 26, 2005
Friday, February 25, 2005
Wednesday, February 23, 2005
Tuesday, February 22, 2005
Click on the above image for a larger version.
Interestingly, in the camera there is more spectral detail in the red channel than the blue. (
This is another project: I have the entire solar spectrum from slightly UV-ward of the calcium H & K lines at 400nm to somewhere near 750-800nm in the near-infrared imaged through my spectrograph and the Ryerson telescope. I want to combine the images into a long continuous image. My own solar spectrum.
The Solar Spectrum -- Magnesium Triplet
Terrestrial Oxygen Red
The Sodium Doublet
Monday, February 21, 2005
It's terrestrial only in the sense of being non-astronomical; to all but astronomers it would be called "atmospheric".
Sunday, February 20, 2005
In retrospect, waiting is probably a good thing, as this means
- I am not a highly competitive student (I already knew that) and
- I was not thrown out immediately.
Saturday, February 19, 2005
Friday, February 18, 2005
1. The digital setting circles slipped off the declination.
2. The right ascension clutch (aka tracking) wouldn't work, or only occasionally would catch.
3. The dome slit was cranky.
All these things affect our motivation to observe, which is the whole reason of being for the RAS. If these items are causing problems, and they are, they need to be addressed and solved in a reasonable amount of time.
For #1, I can fix this easily by moving the setting circle up closer to the moving surface. Once it is done, it shouldn't ever be a problem again and we can get people to use the digital setting circles (designed to help people find stuff).
#2 See a comment below. I think a locknut is warranted, but I think Alex had determined there wasn't enough space for another nut. Can we get two thin nuts? Or, since the motion of the RA naturally loosens this nut, can we put a teflon washer in to help reduce friction?
#3 Physically characterizing the orientation of the metal bars that hold up and contain the slit rollers is important. Are they parallel and level? I recall shimming the bottom rail long ago to keep it level. Part of the problem with solving this is the inaccessibility of the parts, given some of them are 15 feet above the roof of a six-story building.
Oh, yes--the breakthrough last night was hearing parts moving when I tried to move the telescope in R.A. while locked--it gave me the idea to mentalize a force diagram. When the clutch is locked, what forces the scope to move? It's actually transmitted through the R.A. fine motion worm.
The bare bone measured 181 uR/hr when placed just above the detector window.
It measured 170 uR/hr with a sheet of paper between the window and the bone (and a plastic bag).
With a 1/16inch thick sheet of aluminum, the count rate was 42 uR/hr (with plastic bag).
The rate was 15uR/hr from behind the detector and 12 uR/hr from the side. The background was ~14uR/hr.
This suggests 11uR/hr of alpha particles (helium nuclei);
128uR/hr of beta radiation (electrons); and
42uR/hr from gamma rays.
Thursday, February 17, 2005
Ground level neutrons are produced from secondary nuclear reactions occuring from primary cosmic rays hitting atmospheric atomic nuclei. The first neutron monitors were created as a result of John Simpson and his cosmic ray research at Chicago.
Data table for 2004 at Climax, CO: ftp://ulysses.sr.unh.edu/NeutronMonitor/HourlyClimax/Climax2004
Wednesday, February 16, 2005
Thanks to Jason Robertson for the link.
In short, another NASA hyped-up press release with a speculative claim that has no solid data behind it. An Earth-analogue environment that explains a Martian gas fingerprint is not proof.
Saturday, February 12, 2005
The clicker unit attached to the geiger counter
I made the clicker unit with robust design in mind. Therefore, I epoxied everything to the case and it looks really crappy, but it's not going to fall apart in someone's pocket. You can see the basic circuit--9 volt battery switched, which powers the counter through the phone jack. The detection indicator is a negative voltage swing on another line from the phone jack, which switches a PNP transistor. The transistor opens to allow current to flow through the potentiometer, the headphones, and the speaker. The LED is controlled directly by the indicator pulse, without transistor switching.
What's wrong with the design? The headphones should be bypassed when they aren't plugged in, but they aren't, so the speaker does not click without headphones. And, when the headphones are in, there isn't enough oomph to drive the 8 ohm speaker. I tried bypassing the headphones, but I didn't try until after I had assembled the unit, and everything was too cramped to solder.
P.S. What software tools do you use to generate nice schematics? Preferably free or open-source.
Wednesday, February 09, 2005
Anthony Turkevich, Lester Winsberg, Howard Flotow, and Richard M. Adams
"The work reported here was carried out in the old ruling engine room for grating production in the basement of the Ryerson Physics Laboratory of the University of Chicago."
"As mentioned earlier, atmospheric krypton in the 1990s has a radioactivity of tens of thousands of disintegrations per minute per liter. It is now about a hundred times more radioactive than the samples reported on here."
"The largest current producer of radioactive krypton is the French reprocessing plant at Cap-de-la-Hague, which released 1.8 × 1017 Bq of krypton radioactivity in 1994. If diluted by the whole world's atmosphere, this would produce a radioactivity of krypton of 2,400 dpm per liter (STP). Cap-de-la-Hague's output may represent about half of the present input into the atmosphere of this radioactive nuclide."
Tuesday, February 08, 2005
University of Chicago lighting is different. Most pedestrian lighting is mercury vapor. Newer floodlights have been metal halide.
If I took a spectrum of the light pollution, I could measure the strength of a sodium line and a mercury line and compare them to determine how much light pollution is from campus sources versus the city.
For this sort of spectroscopy I don't need a telescope--just a camera, grating, slit, and lens.
Monday, February 07, 2005
1. photograph clicker unit.
2. publish schematic.
3. enjoy the fun of graphs!
Southwest Airlines flight to LAX. I turned on the detector at roughly 12,000ft, and turned it off at the official 10,000ft announcement. According to the pilot cruising altitude was at 39,000ft. The big drop at 3/4 of the way across the graph was a temporary disconnection.
This is the decay of radioactive daughter products of radon-222 being captured on a coffee filter that filtered 15 minutes of air through a vacuum cleaner in someone's basement in Ohio.
If you graph this curve on a logarithmic scale, you get this:
It's not quite straight, but the slope of the line gives you the exponent of the equation far below. The unreadable timescale is the same as the graph above it.
Radon-222-> Po-218 + alpha
Polonium-218-> Pb-214 + alpha
Lead-214-> Bi-214 + e-
Bismuth-214-> Po-214 + e-
Polonium-214-> Pb-210 + alpha
Questions I have that I haven't answered: What exactly is the software recording? What are those numbers? If I listen to the pulses, it seems the software multiplies the number of pulses by 4 to get the observed numbers, which it claims are microRads/hr. If this were a singular nuclear decay, I could deal with it, but it's 5 different decays. So how do I convert into pCi/L of radon? Why does it appear the half-life of the graph is nearly 50 minutes, which just happens to be the half-lifes of the first five decay products added together? Am I recording both the alpha particles and electrons/positrons, AND the gamma rays?
Simple EPA primer on radon: http://www.epa.gov/radiation/radionuclides/radon.htm
Uranium-238 decay chain: http://www.atral.com/U2381.html
Radioactive decay follows A=A(o)e^-kt, where A(0) is the inital amount of material, A is the amount at time t, and k is the decay constant. k is related to the half-life (t 1/2) by the following: (ln 2)/k=t. To get this equation, set A=1/2 of A(0) in the first equation, remove the A(0), take the natural log of both sides, and you're done.
There are lots of fun projects associated with a Geiger counter. Cosmic radiation is one (remind me to graph my week-long Ryerson graph). Live web server graph of current levels is another.
I have another graph of a more recent trip to LAX here.
1. Evaporate sample.
2. Ionize sample.
3. Separate out all ions save +1 charged ones.
4. Accelerate ions.
5. Subject ions to uniform and strong magnetic field.
6. F=qvB, where q=charge, B=magnetic field strength, v=velocity. F=mv^2/r. Heavier ions will deflect less in the field.
7. Measure ions (by current, charge, impact, whatever).
I know some mass specs measure different masses by varying the field strength to sweep the ions by a single detector. A linear CCD (or other long detector) would be able to pick up multiple ions at once.
Measuring current seems too sensitive--can I measure nanoAmps? I know better the response of CCDs than anything else. But these are big particles that won't go far into the detector, and might get stuck in the control gates atop the silicon.
I wonder if I can get more sensitive results by increasing the length of the device. If the ions are deflected by say 0.1 degrees per amu, but I can't see that, I could lengthen the travel distance and they would separate out further on the detector.
Vacuum--a problem since I have no experience.
Can I build a miniuature mass spec using a new technology magnet (i.e., hard drive magnet)?