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And I thought taking a class was a lot of work…

George Privon — Sat, 24 Jul 2010 15:00:48 +0000

Yesterday marked the midpoint of the summer class I am teaching: Introduction to Stars, Galaxies, and the Universe. I knew it was going to be a lot of work but I don’t think I could have possibly understood how much. The content is split more or less between background & stars (two weeks), and galaxies & the Universe (two weeks). We just wrapped up the stars portion with supernovae and the deaths of stars. The summer classes here are intense, two hour lectures five days a week for four weeks. Factoring in somewhere between four to five hours preparation per hour of lecturing and it quickly becomes a sizable investment of time. Oh yea, you also have to write assignments, quizzes, and tests.

Getting to bed by midnight is becoming a luxury, reserved for the weekends! However, having said that I am very much enjoying the experience. I am fortunate that my advisor is okay with me taking four weeks off from research so I can focus on the class (and get a few sweet hours of sleep each night ). Teaching a class has been very informative, not just in terms of teaching, but also in terms of appreciating the broad knowledge base one needs when talking about science. As I am preparing lectures, I frequently realize that my presentation relies on prior knowledge that I cannot assume everyone has. As people say.. if you really want to understand something, try teaching it to someone else.

Two more weeks to go in the class, and we will be getting into the topics where sizes and distances become more and more difficult to comprehend. Galaxies outside our own, ranging from the nearby Andromeda galaxy all the way to galaxies we see when the Universe was a fraction of its current age! But before I can talk about it, I have to write the lecture.

Becoming a black-belt (radio astonomer)

George Privon — Fri, 18 Jun 2010 14:00:34 +0000

I spent the last week down in the New Mexico desert, attending the 12th Synthesis Imaging Workshop (can you spot me in the picture?). The aim of the workshop is to teach astronomers about radio telescopes, particularly interferometers. These instruments are very unique in their methods of attaining the highest angular resolution, despite the long wavelength of light involved. The workshop covered roughly a week and served as a “boot camp” for radio astronomy. The majority of the time was spent listening to lectures which described the theoretical and practical side of using radio telescopes to observe the Universe. However, two days were spent working with real data, and two days were spent “playing” (hiking and getting a tour of the Expanded Very Large Array).

I had been wanting to attend this workshop (which is held every 2 years) since 2005, when I began working on data from radio telescopes. So I was very excited to be there with the other 150 students.

Of course, I suspect recounting the excellent lectures (which can be viewed online or purchased) might not keep you reading, so instead I’ll put up some pictures from the extra-curricular activities from the week..

The first of which was a trip to Santa Fe and Taos. I had never been to either place and it was a nice change from Socorro. I won’t say much, just put some pictures up.

In addition to the two towns we also drove across the Rio Grande and walked around on a large bridge over the gorge. It was a pretty windy day, so our ankles were ex-foliated by the blowing sand

On Sunday all the summer school attendees were treated to a tour of the EVLA. I have been to the VLA two times before, but I can’t turn down a chance to visit a telescope! The EVLA has actually changed somewhat substantially since the upgrades have started. Most of the 20-30 year old electronics have been removed and replaced with new digital equipment to upgrade the instrument by a factor of at least 10. This includes laying optical fiber to collect data from the individual dishes.

By far the coolest part about the EVLA visit was this:

Yes, it is a slightly grainy/blurry picture of the EVLA from a distance. What makes this so cool? When I took the picture, it was taking data for my project! After the tours, I found out that my name and my EVLA project ID were on the screens in the control room. Just as we arrived, it finished taking data on a merging luminous infrared galaxy. I haven’t had a chance to analyze the data, but rest assured I will put something up here once I have.

Another interesting part of the tour was the new Long Wavelength Array (LWA) station at the EVLA site. This is a low-frequency array and they have built the first demonstrator station (picture up and to the left). It’ll be interesting to track their progress over the next few years!

I managed to get a nice panorama of the EVLA as all the dished returned to their stowed position before resuming observations:

There are more pictures online:
Santa Fe and Taos on flickr
EVLA tour on flickr

What I see while remote Observing at the Kitt Peak 12m

George Privon — Fri, 04 Jun 2010 02:51:04 +0000

Right now, I am observing remotely on the Steward Observatory 12m Telescope, which is located at Kitt Peak (KP). I have been to KP before, and seen the 12m before but never used it.

Now, I am towards the end of a 20 hour observing run (the first 5-6 hours of which were done by my advisor), to look at Carbon Monoxide (CO) gas in other galaxies. This isn’t a new phenomenon, CO has been found in many galaxies, including some in the relatively young Universe! CO is used as the main tracer of cold molecular hydrogen, which has no emission on it’s own. (But warm molecular hydrogen can be seen in the infrared). So, astronomers use CO as a proxy to measure the amount of cold molecular hydrogen in galaxies. This is crucial because molecular hydrogen is the bulk of the material that eventually forms stars. Understand where that “stuff” is in galaxies is key to understanding how and why stars form.

So, I am trying to measure the amount of CO in external galaxies so we can understand the amount of gas in them. To do so, I am using a 12m diameter telescope which is optimized to observe at wavelengths around 1mm (or about 2,000x longer than what the human eye sees). It looks similar to a satellite dish because it also receives radio waves, but these are higher frequency (shorter wavelength) than the satellite dish on your roof.

So, it’s all well and good to say that I am looking for CO.. but what do I actually see?
Since I am using a radio telescope with only 1 dish (as opposed to something like the the Expanded Very Large Array), I don’t get to see an image . I only have 1 “pixel” on the sky. I can move the pixel around the sky and “map” out an image, but if I only point the telescope once, I only get 1 point. Unfortunately for me, these galaxies are smaller than that “pixel”, so I can’t map them like this. If I want to see a picture of the CO in the galaxy, I need to use a telescope which can see finer details.. something like the Atacama Large Millimeter Array!

But, even with just one “pixel” I can learn a lot about the galaxy. If I break the light up into different wavelength bins, I can learn about how the gas is moving in the galaxy due to the doppler shift. That is shown as a spectrum (galaxy name removed to protect the guilty):

The broad bump in the middle is the radio waves coming from CO gas in the galaxy. Note the bottom scale, which shows that throughout the galaxy, the CO is moving over a range of about 400 km/s! While this sounds fast, it is about the typical range in velocities over a whole galaxy, so it’s not too surprising. This is probably just gas rotating along with the galaxy. The spikeyness is noise. We can’t make perfect measurements due to many issues (atmosphere, the electronics, etc). But the broad bump is definitely real.

So, how do I get that spectrum? First, I’m sitting at my desk:

My computer (the big one on the left, I’m writing this on my laptop to the right), is connected to a computer at the telescope on top of Kitt Peak. On my screen are a bunch of windows which keep me informed about what is going on (click to see a big version):

Most of the labels are self-explanatory, but the chat box allows me to communicate with a telescope operator and tell them which target i want to look at and how long we should look at it. The “catalog and ephemeris” window lets me load a list of sources and it shows where they all are on the sky so I can pick the best ones to observe (want ones that are high above the horizon). The “telescope info” box has lots of data on where the telescope is pointing, how much noise will be in my data, what frequency I am observing, etc. Very useful.

Using the program above, I work with the telescope operator to point at targets and collect radio waves from them. That data is then saved. Computer software then processes the data to remove the effects of the atmosphere and calibrate the data. And, voila! you have the spectrum above.

Despite the fact I am not at Kitt Peak, the observing is fairly similar. If I were there, I would still have the same program open on the computer, only I wouldn’t have to type to the telescope operator. And even more fun, I would be able to go outside and see the beautiful night sky from the top of a mountain.

For a bit of a comparison, here’s what observing at an optical telescope looks like.

What observing actually looks like

George Privon — Sun, 18 Apr 2010 23:17:54 +0000

I have written a bit about observing at various telescopes, most recently being my 4 night run at the Steward Observatory Bok 90″ Telescope. You might wonder what I (and other astronomers) actually do while observing, where we actually are while the telescope is staring up the sky.

The days of being near the telescope are pretty much over for scientific observing at large observatories. Most observing doesn’t look like this anymore (in addition to the fact that this photo is staged: light are on!):

Nowdays the astronomer (and frequently a telescope operator) sit in a control room which is thermally isolated from the telescope. In the case of the Bok 90″ and most older telescopes the control room is inside the dome and near the telescope. However in some cases, the control room is in a separate building! Here is a picture from inside the Bok control room where you can see the back of the telescope through the open window in the upper right. The window is of course closed while we’re observing.

Modern telescopes can be controlled via specialized computer software which can point the telescope and run the various instruments. So control rooms will have multiple computers to run the telescope, acquire data, and analyze that data. There is also frequently a telescope operator employed by the observatory who’s job is to operate the telescope. This can involve moving the telescope from target to target, focusing the telescope, and troubleshooting. The operator will have their own desk and set of computers to manage this task.

(Note: I have uploaded a few pictures to flickr which show the control room. I encourage you to click on the images and go to the flickr page. There are notes on the images showing which computers do which tasks.)

At the Bok 90″, this is the telescope observer’s area:

Here’s a close-up view of the telescope control desk (no smoking, unlike Edwin Hubble in the picture above):

Since the telescope pointing and control is taken care of by the telescope operator, this leaves the running of the scientific instruments to the observing astronomer (me!). In my case, I am using a camera to image several galaxies I am studying. In the observer’s area of the control room there are two computers: one for controlling the instrument and one for looking at the data from the camera.

So while observing, I use the left-most computer to open the shutter on the camera and take an image. That image is then downloaded to the computer next to it (the one with 2 monitors), where I can view it and analyze it enough to verify its quality. For most of the night the observer will sit at those computers, taking and analyzing data.

Kitt Peak Observing Update

George Privon — Sat, 17 Apr 2010 21:20:59 +0000

2 down, 2 to go. So far I have had tolerable weather for observing. The first night was somewhat cloudy and we lost some time but conditions overall were less than idea. Last night was better from the standpoint of clouds, with only a little bit of haze between the telescope and the galaxies I was observing. Despite that, I have gotten some good data.

The day before yesterday my parents were able to come up to the mountain for a quick visit. They were on their way to Texas and swung by to see the observatory. I showed them the Bok 90″ and we walked inside the Mayall 4m dome and over to the McMath-Pierce Solar Telescope. A volunteer was operating a Coronado solar telescope with a Hydrogen-alpha filter. We were able to see a large solar prominence on the surface.

It was great to see them and also to get to show them around my “office”

Things are looking iffy for tonight, but even worse for Sunday. Cloud cover moving in, so we will see what happens. It’s approaching time to head back to the telescope, but I think I will enjoy the view for a few more minutes before I go:

Live, from Kitt Peak!

George Privon — Thu, 15 Apr 2010 02:01:32 +0000

After a bit of air travel, some driving, and then a few hundred feet of walking, I am now sitting in the control room of the 90″ Bok Telescope at Kitt Peak. It is just around dinner time here, so I currently have the room to myself. My observing run starts tomorrow night, but I am here a day early so I can be certified to use the 90Prime imager. So, for the evening I am tagging along on someone else’s run.

We still have another hour or two until sunset… but things will start moving along shortly. If you want to be up to date on the action, check my twitter feed.

Upcoming observing trip

George Privon — Sun, 11 Apr 2010 16:38:11 +0000

In a few days I will be flying to Tucson, AZ to do some observing at Kitt Peak National Observatory on the Bok 90″ Telescope. I have 4 full nights, using the 90Prime imager. The dates are around New Moon, so assuming the weather is good we will get some great data. I will be bringing my own camera and taking pictures if I have time while observing.

If you want to follow along on the run, I will be posting short updates to twitter through the duration. This will be the first of 3 observatory trips in 3 months, so I will be tagging updates with #3in3 on twitter. Feel free to comment on posts or @reply on twitter if you have questions. I will do my best to answer them, but the answers may not be immediate.

Finally, clear weather for public night!

George Privon — Sat, 10 Apr 2010 19:58:19 +0000

Last night was the semi-annual Fan Mountain public night. Unlike the previous two or three iterations, we had beautiful clear skies. The sunset was gorgeous (apologies for the shoddy cameraphone pictures):

Venus and Mercury were also easily seen just after sunset. (Same caveat about the cameraphone, which barely picked up Venus):

We began tours at 20:00, 40 minutes apiece for both the 40″ and 31″ telescopes. As in previous iterations, I gave a presentation on the FOBOS spectrograph. The last tour passed through around 23:00. Although the size of tours dwindled towards the end, we had roughly 300 people come through. Not nearly a record, but still a great attendance!

I had a lot of good questions from visitors while at FOBOS. I find answering questions to be the best part of interactions, it is when you can really see what people are interested in. My ultimate goal with outreach is to share science, whether that ends up being the science I do or someone else does is secondary. As long as I can talk about something that interests the public, I consider it a success.

After the tours were over, I quickly packed up my station (putting away fiber-optic demo and the diffraction grating) and rushed up to the 40″ before it closed up for the night. They had been looking at Saturn. I must say, looking at Saturn through a 40″ telescope is quite impressive. The seeing was fairly poor though and you could see the turbulence in our atmosphere in the form of ripples going across the image of Saturn.

If you are interesting in the Fan Mtn public night, the next one will likely happen in October. Tickets, which are free but only available in limited quantities, will be available a few months beforehand from the UVa Astronomy Department.

Guest on the Public Universe radio show tomorrow

George Privon — Wed, 24 Mar 2010 16:45:27 +0000

I will be a guest on the Public Universe radio show tomorrow morning at 10am (EDT). The topic will be my research, upcoming trips, and photography. To tune in, visit the Public Universe radio page. The show will be archived and available online afterwards.

EDIT (25 March 2010): The archive of the show is online here.

APOD: “Exceptional Rocket Waves Destroy Sun Dog”

George Privon — Thu, 25 Feb 2010 01:20:33 +0000

In case you missed it yesterday, a picture of mine from the Solar Dynamics Observatory launch was the Astronomy Picture of the Day (APOD):

APOD: 2010 February 23 – Exceptional Rocket Waves Destroy Sun Dog

It was very cool to see the picture on APOD. I got a decent amount of feedback and contact from people. Lots of it on twitter but also a few emails. There was also a healthy discussion of the cause of the shockwaves on the APOD discussion board.