Our Students Visit and Observe at the Green Bank Observatory

Being able to breathe a few steps away from the largest steerable thing on the surface of Earth is something an astronomy minor would not say no to, especially if that thing is a telescope which has the power to answer mankind's biggest questions.

We are talking here about the Robert C. Bird Green Bank Telescope, the site of which (The Green Bank Observatory, or GBO) our astronomy minors had the chance to visit and explore.     Eighteen of our students were accompanied by four faculty members for an overnight trip there, where they got the chance to observe with GBO's 40-foot teaching telescope and participate in quite a number of other educational programs.

Overall, the experience seemed to be overwhelmingly positive: one might not get the chance to see so many smiles and hear "wow"s from physics, computer science, or engineering majors, all while learning about the our host galaxy, Milky Way, through their own observations of Hydrogen emission.

Far away from hot O and B-type stars, the hydrogen in space is in the ground (i.e., lowest energy) state.   However, when the spin of the electron flips from being parallel to anti-parallel with the spin of the proton, there is a tiny energy difference that is emitted at the wavelength of 21 cm (or a frequency of 1420.4 MHz).   While a hydrogen atom can wait on average a few million years before it undergoes this transition (YES, it is this rare!), the large amount of hydrogen gas makes this particular emission one of the most prominent and easiest to detect with radio telescopes.

The 40-foot spectrometer allows us to detect radio waves from this particular transition by
blocking (filtering) out all of the waves but the ones coming at this exact frequency.  This 21-cm line radiation provides the best way to map the structure of the Galaxy (note: for astronomers, Milky Way is the only galaxy with capital "G").

Here is an example of detection of (the center of the) Milky Way's emission at 21 cm with the 40-foot telescope's spectrometer (sorry folks! no pic from there). The red line is a calibration measure, while the black line records the data, i.e., the intensity (in Jansky units) as a function of frequency.  The two  strong peaks at the left side of the spectrum show detection of HI at two different frequencies: the strongest peak is located at 1419.5 MHz, and the other at 1485 MHz, depicting two different clouds of Hydrogen emitting the 21-cm transition that is redshfited (smaller frequency, or longer wavelength), implying that the detected Hydrogen is moving away from us (while rotating in the disk of the Galaxy).   The peak at the far right depicts an artificially created signal of 500 Jy, for calibration purposes.

Multiple data sets from eight groups of students, acquired during the night, were collectively analyzed the next morning.   After not much debate, there was a pretty good agreement that the data shows strong evidence that Milky Way has the shape of a flat disk, that is rotating counterclockwise.

Here are some of the students' thoughts about this trip, with some cool, funny, or downright amazing things they have learnt:

* Mary Ogborn & Ebony Williams (physics majors):  This trip really illustrated aspects of radio astronomy that I wasn’t aware of before. Although I was aware of radio interference, I was not aware of how sensitive these telescopes could be to various sources [...] The control room was also impressive, as it was copper-insulated, in order to keep in the radio waves coming from all the computers and machines. [...] it was interesting to step into the past and see how the original radio astronomers operated these huge telescopes. I can’t imagine having to manually dial in the declinations, change the frequency every second by pushing the mark button, and having the chart reader draw out the peaks without any other form of labelling. [...] I now understand how observatories in the past would hire people to be ‘computers’ before the advent of computers.

*Ryan Ferrell (physics major):  I did not expect to be able to extract this much information from the data which made me appreciate how much information can be brought out of even just a little data.[...] I learned was how many common things cause radio interference. I knew previously that most electronics caused radio interference, however I did not know that signals from modern electronics are a billion times stronger than the radio waves that the GBT was measuring from the Milky Way. [...] I never knew the GBT was the largest radio telescope in the world or that the Drake Equation had been thought of there. [...] I was very surprised to find the control center so close and surrounded in a giant Faraday Box. 


* Tanna Walters (engineering major) & Brandon O'Neal (physics major):  This trip to Greenbank Observatory has taught us a good bit about the actual ways in which the data is collected and how the hardware works.  GBT actually has a clam-shaped dish and an arm that is off-center that collects the radio waves. The purpose for this is to allow for the collection of more radio waves as opposed to parabolic telescopes that have the receiver in the middle of the dish, blocking a significant portion of the incoming radio waves.   [...] we learned just how sensitive the telescopes are to interference (RFI). Even taking a picture with our phones could interfere and ruin astronomers’ data all over the world. 

In the control room of the GBT

* Tom Gagne (computer science major) & Kris Pickens (physics major):  We learned the remarkable fact that if a cell phone were placed as far away as Mars, it would still outshine the brightest distant radio sources by several orders of magnitude.  So we had to turn them off when out among the telescopes. We also learned that a shipbuilding company built one of the telescopes and put an enormous ball-bearing in it. The ball-bearing was so large that the bridges had to be fortified along the path of the train that took it there. 

* Cameron Kelahan (computer science major):  For the first time, I was able to operate a radio telescope and perform radio astronomy. I learned how to operate a 40 foot radio telescope, the equipment that goes along with it, the meaning and importance behind the 21 cm line, and how the shape of the Milky Way was originally discovered. I also got an idea of what it may be like to work at an observatory from talking with [GBT operator].  His job seems very interesting and also challenging! 12 hour shifts are something one can get used to, but there is also a lot of responsibility that goes into operating a MASSIVE TELESCOPE!  The overall experience [...] allowed me to strengthen friendships with classmates and possibly future colleagues while learning with them about something we all have a passion for.  

The first look at the Sun

The Sun has been doing what it is doing now (fusing Hydrogen in its core) for about 5 billion years (and will continue his endeavors for another 5 billion years). We are all witnessing this activity, and are able to go on with our lives mainly as a consequence of what the Sun does and has to offer, and still... some of us took a good look at our star only yesterday...

Students enrolled in one section of the Introductory Astronomy (Astr121) class got the chance to see the Sun through a Coronado solar telescope and monitor its motion in the sky with Sunspotters. The solar observing session was only possible because the students enrolled in the General Astronomy II class volunteered (their astro class time) with setting up the telescope together with the necessary arsenal (counterweights, lenses of various resolving power, etc.). You might be pleasantly surprised to hear what those students had to say about this event (long time sought after; it rained a lot lately here):

First off, I would just like to say thank you for giving us the chance to look through the “Coronado” like that, because it was such an incredible and enlightening experience. I’ll be honest, I didn’t really know what to expect or what the sun would look like through the filter on the telescope. While I certainly expect it to look like a blood-red disc, I also was not prepared for just how much detail is still visible through the telescope. When I first looked through the telescope, the sun was moving pretty quickly and almost disappeared from view; but, in that small portion, I was able to see the surface turbulence swirling about in constant motion, as well as several sunspots which, surprisingly, appeared slightly brighter than the rest of the surface. After the line went through and several of my other classmates returned for a second look, I joined them; the students helming the telescope kept changing eyepieces, so I wondered if that would give me a different view. When I looked through the “Coronado” for a second time, I was treated to an even larger vision of our star and that allowed me to see even more. Once again, I saw the constant turbulence upon the surface, as well as sunspots, but this time I was able to see a solar flare. It exploded out of the edge of the sun like a fountain of red wisps; my words can’t do it justice, but it was just so incredible to see. I mean, it’s one thing to see the picture in the book, but it’s another thing entirely to actually see it with my own eyes. (Madeleine Cassier; Media Arts and Design; Digital Video and Cinema; Proud member of the Marching Royal Dukes)

Viewing our sun through a telescope in class was a fascinating experience!

At 8:45 A.M. this morning, our class was treated with the privilege of interacting with sunspotters as well as one of the astronomy department's telescopes, set up by several advanced astronomy students. A sunspotter is a wooden device which reflects an image of the sun onto a sheet of paper through the use of a lens and mirrors. This tool is one way we can view the sun without damaging our eyes from the sun's damaging UV rays. Another function of a sunspotter is to allow us to track the rotation of the earth as the image of the sun moves across the paper sheet over the course of a day. A sunspotter also allows us to see sunspots on the sun's surface, the photosphere, which we could not otherwise see with our bare eyes. Through the three sunspotters available for us along the sidewalk, we could see the reflected image of our sun as a palm-sized white circle with many small speckles (the sunspots).

The view from the Coronado telescope was quite unique, at least in comparison with my amateur experiences with telescopes from childhood. With the initial positioning, the advanced astronomy students had us looking at the sun as a deep fluorescent red circle which filled the field of view on the telescope. The red color is not the color of the sun as we would recognize and label it. Rather, it is the result of the coloring of the filter on the lens. Amidst this redness, we could see sunspots. With a few minor adjustments to the telescope's position by the advanced astronomy students, we were able to see swirling movement of the gases on the photosphere, in addition to the sunspots we had seen previously.

Thank you for the delightful morning! (

Caity Wilkinson;

Psychology/Pre-Law/Women's and Gender Studies

)

Had a lot of fun looking at the sunspotters and through the telescope this morning! The sun moved pretty fast and the first few times I looked at it with the telescope, there wasn't much to see beside the surface. Eventually I got to look right after it had been readjusted and it was a really beautiful sight seeing the edge of the sun against a dark background! I wish that I had more time to play around with the sunspotters, but unfortunately my next class is back to back with astronomy. (James Cole; computer science major)

Today in class we looked at the sun (not directly) through the telescope. The first time I looked was right after a classmate who was just in awe of how wonderful it was. I looked and all I saw was a mass of red. I was kind of confused because it didn't seem very glorious to me. A little while later I tried again, but this time a friend told me to try without my glasses because it worked for him. It looked a lot better surprisingly. My glasses are for distances, so when something is that close to my eye it is a lot clearer. It definitely looked way cooler. I could see more details of the surface, it was moving slightly and I also saw a spot that was kind of swirly almost. It looked like when you put oil into water, and it sits at the top and swirls around a bit. It was really pretty and interesting to look at.

I went over and checked out the sunspotters right after, and I thought they were wicked cool. How interesting is it to be able to see the sunspots that easily? I thought these were awesome inventions and I was glad to learn about them. One of the science students helping us was saying that we could even see the atmosphere. If you watched it, it flickered slightly and was kind of moving, and that was apparently the atmosphere. I haven't told my Mom much about in the classroom things, but this is something I want to tell her about. Thank you for this experience! It was a really cool thing to do! ~Megan Kelleher (music major) :)

After learning in the classroom, we took our activity outside to check out that familiar star known as the sun. We learned how to use a few different instruments. First of all, there was the sun-spotter, which is the safest way to observe the sun. With this, we were able to see the entire sun, as well as sun spots. It works with the use of several mirrors that reflect the sun onto sheets of paper. The sun ends up moving on the sheet of paper due to Earth’s rotation. We were also able to look through a telescope with light filtering so we were not blinded by the sun’s rays. The sun was a reddish color, due to this filtering, and if you looked at the edges of the sun, you could see the solar flares. (Jarrett Apicella-freshman)

Though the SunSpotter doesn't magnify our sun, it was amazing to see the actually sun spots and their current location on our star. When looking through the solar telescope with the hydrogen alpha filter the sun appeared red. When you took your time to look through the telescope and it was actually focused on the sun you could see solar flares from different locations on the sun. It's one thing to see flares in pictures, but when you actually see them for yourself through a telescope, they're that much more impressive. (Matt Zurlo; Justice Studies/Military Leadership)

Through the telescope the sun looked very red and the surface seemed very textured. After someone told me to direct my attention to the top of the sun i noticed an area that looked like a solar flare. Until today i didn't know that you could observe the sun through a telescope and it was a very interesting thing to see. -Kenneth Huffman (music major)

I could see the surface of the sun. It looked like molten lava. The sunspots showed up as brighter spots because of the Wavelength (that's what one of the helper students said). I could also see small flares off the edge. With the simple sunspotter, I could see sunspots as shadows. One of the other helper students explained that it works the same as a telescope and projects the sun onto the paper. I was really surprised you could see the sunspots that way. I've been looking forward to using the telescopes all semester and I'm really glad we finally got to go out and use them!

With the sunspotter, we looked close at the projection of the sun, where we were actually able to see sunspots; we also marked the positions of the sun over a short period of time to see the path of the sun. I was surprised to see the speed at which the sun was moving. We also viewed the sun through a telescope that gave us a more detailed image of the sun providing color and better resolution. The sun was showed as a deep red color due to the Halpha filter and you were able to see darker spots, which were sunspots, along with solar flares coming off the edges of the sun. (Andrew Sengstacken; Computer Science)

Thank you so much for the experience of letting us see the sun in such a new way. I loved the “sun spotters” as they were simple yet an effective way of viewing the sun. I could see the tiny black spots, which I assume were sunspots, as they moved around the sun. Also with both the telescope and the sun spotters I could actually see the sun moving. I know that the sun moves across the sky, but seeing it move so quickly was amazing. The best part was seeing the sun through the solar filter telescope. At first all I could see was a red disc slowly moving up but the there was a quick burst of gas from the bottom, which was solar wind. It was so amazing I went back for a second look. During that look I noticed the visible surface of the sun was also moving. It was an amazing experience, thank you very much! (Megan Tuskey; communication studies)