Teachers Sciencing
08.06.2018
SCIENCE!...(Didn't I say that already?)
Okay, so we taught the 9th graders, and we went up in the big scope, and we sat around the house and manage to eat well...but then there is the Science to do.
Then and Now
Before I get started, I want to give some historical context to our horn scopes. Sitting outside the Jansky Labs (the main research facility at GBO) is another scope with a nice plaque. It truly looks a lot like what we made. It was a pioneering technology detected Hydrogen for the first time, and now, about 70 years later, a bunch of high school teachers are using a similar thing to repeat their experiments...cool!
Hey, that's what we are doing!
Harvard's and Ours...same receiver can size
Okay, slightly bigger light gathering power
Somewhere early in our stay, Pranav rounded up the troups for an after lunch meeting so that we could each take the lead on a science project with our horn scopes. It was then up to us to decide when, who, and where each experiment would take place. The experiments were kind of divided into two groups: Calibrating the stuff we made (LNA and Horns) and using our stuff to see the Milky Way Galaxy.
I want to finish this blog with this entry, but I don't have a complete set of pictures for all the experiments that I took. As they come in from my colleagues, I will add them in.
Alphabetically:
Alexis' -Low Noise Amplifiers (LNA) Comparison- Each signal we receive with the horn scopes will have "noise" (unwanted signal strength) contributions from the sky, the horn, the Can, and the LNA. (SCIENCE 101 STUDENTS! - CONTROLS AND VARIABLES in an Experiment) So, we used the SAME horn and pointed to the SAME part of the sky (Our Controls), and just switched out the 10 or so LNA's (Our Variable) that we had. There is actually the HOT-COLD Shed that is used specifically for this purpose for the professional devices that they use here at GBO. The big round circly thing is for mounting the receivers to be tested. The winning LNA got the LNA Award (Let's Not Acknowledge Award) So, we don't really know who won!
Getting Ready to LNA Test
A Horn is worth 1000 pictures...ok, just 3
New John was dedicated to science right to the end.
Dan's - Horn Comparison Same place- HOT COLD Shed, Same Sky, Different day, different Variable- The Horn/Can combo. We used one of the better tested LNA's, even though they all did pretty well, and switched out the Horns to see how they did. Thanks to Dan's activity with the students, we had about 6 or so extra Horn/Can combos. Again, there were some variations, but the horns all did pretty well with offering minimal noise. There was a winner, and this award was called "The Horny". To protect the integrity of winner, I won't say which one horn was the Horny one.
This is your leader?
Howard's - Whole Sky Drift Scan Survey This was, by far, the most encompassing experiment , in time and effort. The idea was to set up 9 horn scopes arranged in such a way to cover the line from due south up to the North Star. Then, let the scopes sit for 24 hours while the whole sky "DRIFTS" by. So, first, Howard had to find a forecasted 24 hour period without rain...which turned out to a tough thing to do, and we may have hit the only one in our two weeks here...There was a lot of rain in our time here. We actually had to make a few new bases for the extra horns that the kids made, and we had to set up a power station so that 9 laptops could run for 24 hours taking data. The hope was to be able to loosely maps the location of the Milky Way in the sky. The results were pretty good. Ideally, one should do this for 3 days at slightly different angles so to get overlapping data to smooth the graphic. There was about a Gigabyte of data to be sorted through and mapped. This would be a doable experiment at a school. One horn scope could do it, but it would take about a month of solid data gathering, or at least thirty individual 24-hour scans.
Anyone for Ice Cream?
Gotta Know Where to put the Scopes
Building the Array
Gotta Shade the Computers
...and now a word from our sponsors
Like the Energizer Bunny
24 hours...done!
New John's - Beam Width
MINI LESSON FIRST --An optical telescope with a curved mirror is using optics geometry to bend light and reshape it through an eyepiece and send it into your eye where your brain processes the signal and you see things that look closer, brighter, and in more detail. Let's consider the Moon. It takes up about a 1/2 degree angle of the sky. So, 2 Moons per degree times 360 degrees in a full circle means we could put 720 Moons side by side to wrap the sky. Still, when you look at the Moon with just your eye, you can see details on the Moon (Craters and Seas). This means that the smallest thing you can see is about 1/10 of a degree. This is known as the ANGULAR RESOLUTION of your eye.
The radio horn scope channels the radio waves into the can where the antenna picks up the signal. This helps that amount of signal coming in, but does little for the resolution. The resolution has been suspected to be, not 1/2 degree, but 15-20 degrees. It is like putting a white handkerchief over your eyes. You would only be able to tell if the Moon was in your field of view because the handkerchief would be brighter.
Okay, back to New John's Experiment. He used the Sun to cross the field of view with two methods. He did 4-hour drift scan letting the Sun move from clearly outside the range of the Horn, let it cross, and recorded the intensity of the Sun's radio brightness as it crossed the field of view. (The Sun is "bright" in all wavelengths) The second method was to methodically move the horn past the Sun. This makes it a ten minute experiment vs 4 hours.
Old John - Quiet Partner John was behind the scenes on many of the experiments, and his data management block in the program has made doing many of these experiments, especially mine, much easier. Thank you.
Tad's - Velocity vs Radius Curve of the Milky Way I can't go any further without saying that Old John deserves equal credit in setting up this experiment. We both expressed equal desire to investigate this one. Since he had so much else going with his program block addition, he let me take the lead on this.
We used 4 horns to look, systematically, along the galactic plane from its center in Sagittarius, along the first 1/4 (90 degrees) of its full wrap around the sky. It was probably the busiest experiment to set up ahead of time, planning where to point the scope at specific times to see the galactic plane in 7.5 degree intervals. We spent about 2 hours from 10 pm to midnight on 7/26/18 looking. We used 4 horns pointing at the same point in space to build confidence in seeing that the spectrum looked similar to each other...and to make sure that we got at least one good data point per spot. Even with that, we did have one location that all four of us failed to get a decent reading.
Practicing alignment for tonight's performance
Which Way to Point?
There is a lot of data that comes with this project, and a lot of speculation as to what exactly to do with this data in mapping the Galaxy. Due to our low resolution, we can see general trends. Professional astronomers use higher resolution scopes to get more detailed data, still there is a lot of guess work in creating a map of our galaxy and exactly where the spiral arms are. I will present some data here, but there is more work that could be done...I will save it for my astronomy students to work with!
Galactic Plane Results
Undergrads Rhys and Andy- Detecting Pulsars with 4 Horns Though they were part of our program, these two were a constant presence. They were taking the scope design and trying to stretch the capabilities of putting 4 horn scopes together in unison to see if they could detect the presence of a pulsar star. The pulsar has a much weaker signal strength than the Milky Way we were looking at. Also, the "Pulse" in "Pulsar" is the fact that it rotates quickly and sends its radio signals out in regular pulse intervals in time. Their work to try to weed this information out of the data involved a much more intimate encounter with understanding the software than we had to deal with.
Yeah, but I have 4 of them!
After all there work, they left without conclusive evidence that they had detected the pulsar. There is still a chance that the info is in their data waiting to be found, but there is also a valuable lesson for any scientist in that failures are part of the game, and they make the successes all the more rewarding. What an incredible lesson for undergraduates to learning. Failure in a class test means you didn't answer the question the teacher wanted, but you can look it up. Failure in an experiment means you didn't get the answer you wanted, but nobody knows the answer and it is still yours to seek...don't give up!
Back to Dan We all got a chance to go down to the 40 ft radio telescope (with resolution of about 1 degree) and learn how to use it. It was a quick lesson, and easily forgotten if not repeated. Dan took on the desire to work with the scope a lot and eventually got about 120 data files of different things. We (Old John and I) were trying to coordinate our galactic plane data with Dan to get a 5th, much higher resolution, set of data for our experiment. Unfortunately for us, the STEM students were all expected to do some data recording using the 40 ft scope, and gobbled up much of the scope time, so Dan wasn't able to get data to go along with our data.
One for All, and All for One
This National Science Foundation granted RET (Research Experience for Teachers) was truly that. The fact that we got to DO SCIENCE as described in this entry was a major accomplishment for us all. I would like to finish by saying that I was intrigued by the very diverse group of 6 teachers. We have a wide spread set of backgrounds, and teaching locations and situations, yet we had the commonality of finding some reason to come to DSPIRA. It made for a very full experience in seeing the diversity of the lessons we generated for the students, and the in the science experiments we did. We had our ups and downs, agreements and arguments, but in all, I think we all benefited from each others contributions and skill sets.
And, of course, a thanks to Kevin Bandura and Natalia Schmid for developing the DSPIRA experience, proposing it to NSF, and getting it funded!
My picture...Almost All...waiting for Howard to figure out his camera delay feature
And after the wait...
The Whole Gang!
