So, my next story from my trip is from way back on June 13 (Yeah, I’m a little behind…). This was in the middle of the Synthesis Imaging Workshop, the day after the US heroically beat England 1-1 to kick off our hopeful run to the World Cup. The previous day had hikes that I skipped out on and a pool party I didn’t swim at (it was cold, believe it or not). So, on Sunday, I made full use of the planned activities — namely, a trip to the Plains of San Agustin to visit the Very Large Array.
Here are the corresponding pictures for this event, by the way: http://picasaweb.google.com/113708845568647784424/20100613VLA#
The Very Large Array (VLA), for those of you not in the know, is the reason I’m in New Mexico. Not to observe on it or to work on it, but because the Socorro facility of NRAO is in Socorro because the VLA is 50 miles away. Since large arrays need lots of open space far from sources of radio interference, the Plains were a good choice for sticking an array. And, since all the support staff and scientists need a place to live, NRAO science facilities sprung up in the nearest mildly large town, Socorro.
The VLA consists of 27 ~10 story antennas (from base to the top of the subreflector when the dish is pointing straight up). arranged in a Y shape — or, more accurately, in three lines angled 120 degrees from each other. One arm points North, and overshoots the intersection of the three arms by two antennas (it has eight antennas North of the intersection and two South). The other two arms, by doing the geometry, point Southwest and Southeast. At the time of my visit, only 26 antennas were in the array — I think one was taken from the North arm for repairs. There is also a 28th antenna at the site, allowing for technicians to always be working on one dish.
Currently, the VLA is undergoing an upgrade to the EVLA (The E stands for Expanded!). The biggest part of this (aside from design, software support, and calibration standpoints) is installing new equipment on the dishes and upgrading the calibrator (see my previous post for a simple explanation of the purpose of the calibrator). It’s kind of a big deal, and I’ve witnessed astronomers having heated arguments about how the implementation is going. Not everything is rosy in the sciences, I fear.
So, I woke up early that Sunday and walked to the AOC (where I work) in hopes of hopping a ride on the buses before the buses left for the hotels. We succeeded, and therefore had first pick at seats on the bus (boo-yah!). After sitting around for about ten minutes, we rode over to the hotels and picked up everyone else in town for the conference. Then, we headed out to the VLA.
When I said that there is stuff in Socorro because of the VLA, I don’t want to give the impression that they’re close. It takes more than an hour to get out to the VLA, and most of the scenery is pretty boring. The high point of the trip, aside from when you get close enough to see the array, is passing through the town of Magdalena (population 913, according to Wikipedia). Other than that it’s a lot of open space, mountains in the distance, and cows. So I took the enjoyable option of sleeping on the way out. Aside from a brief moment of awakeness as we passed through Magdalena when I turned off my phone (phones = Radio Frequency Interference (RFI), which you don’t want climbing all over your antennas), I slept until the sounds of people taking pictures woke me up just outside the array.
Another thing I should probably mention is that the Plains of St. Agustin are ~3,000 feet higher than Socorro. So, showing up there in the morning was actually kinda chilly, especially since I was wearing shirts. By the end of the day my decision paid off, but it was initially not the best of options. After getting out of the bus, I initially put on sunscreen and grabbed a bottle of water (that didn’t last that long). By chance I joined a tour group that was going to go up on the dishes first.
One of the perks of being an astronomer (and I assume this holds true for most fields) is getting special access. Regular people visiting the VLA can get within, oh, ~40 feet of one Antenna. They also aren’t supposed to be walking along the arms or visiting the ALMA antennas. Those of us present that day, however, were given full access. Huzzah!
Not that far up the antenna is the pit room. That’s where all the cables come down through. There’s some equipment there, but it really isn’t TOO exciting. If you’re afraid of heights, however, it’s probably about as high as you want to go. It’s maybe 10 feet off the ground. Probably ~40 feet up (these numbers I’m guesstimating as I go along…I’m bad at estimating distances, especially vertical distances. My pictures will give you the best impression.) was the elevation gear, a large, greasy gear that controls the elevation of the dish. Also, there were cryogenic coolers, whose power requirements take up over half of the operating expenses of the array alone. They look like Air Conditioning boxes (the ones you set outside, not window units).
Up another flight of stairs, over some pipes, and through a narrow passageway is the vertex room. Located directly under the dish itself, here is the front-end unit, the feed horns, and all of the other instruments used to get the data off the dish and pipe it to the correlator. It’s capable of producing a lot of RFI (electronics tend to do that, even those that don’t actively transmit), so there was a bunch of radio shielding around the electronics. After getting a ~8 minute talk about everything inside the vertex room, we walked back into the narrow corridor and climbed a ladder onto the dish itself.
Several things about the dish. First, it’s bright. They’re painted white, and they’re designed to collect all sorts of light. Also, unlike optical telescopes, they aren’t as finely polished (find your favorite optical astronomer and ask to walk over his or her mirror…I doubt they will appreciate your request.) so you still get solar reflections even if you aren’t at the solar focal point. Even with sunglasses on, it was mildly blinding at first. Second, despite the size of the dish, walking on it is a little unnerving. You can feel how thin the metal is, which is not something you want to feel ten stories above ground. Third, the dish is parabolic, so the slope picks up a bit near the edges. Walking near the middle was easy, but, near the edges you feel like you’re going to fall over (also not the most pleasurable of feelings). Finally, they’re huge. You can probably tell in my pictures, but there is a lot of room up there.
The dishes were pointed more or less straight up, so I walked over to the edge to look around. It got tough to stay standing, so I adopted a Captain Morgan pose, leaning onto my leg further up the dish. Some of the people I was with didn’t enjoy that thought and stayed firmly in the center. After about ten minutes of pictures and gawking, we headed back down. Oh, one last thing about the antennas I should probably mention — the walkways are all metal, specifically the kind you can see through. Once again, a bad place to be if you’re afraid of heights.
After we were back on the ground, we headed over to the operations center. We took the same route into the building Jode Foster took in Contact, but we didn’t have the luxury of disappearing into the magical studio set built for the movie. (If you’ve never seen Contact and visited the VLA operations center, at one point JF runs into the building, runs through a door, and heads up to the control room. However, everything after that door was made in Hollywood because the actual control room wasn’t “hi-tech enough.” Inside, we saw the correlator, the clocking MASER, more circuit boards, and the control room. The control room has a really awesome view of the array itself, pointed more or less toward array center. There’s also a bunch of computers, but that’s to be expected with science. Perhaps best of all, they have a signed picture of Jodie Foster with Arecibo in the background (it’s in my pictures).
Once done there, we headed over the visitor’s center/gift shop, where we lingered for several minutes. Then, onto a bus to visit the Long-Wavelength Array (LWA). You need to look at my pictures to appreciate it. It’s ~200 metal things sticking out of the middle of the desert (in sight of the VLA). They are working on getting several thousand more out there, but, for the time being, it’s still a lot. The guy who talked to us about it brought his ~14 year-old son with him, who has been helping with the assembly. I guess being related to astronomers gets you almost as much access as being an astronomer. The two of them (man and son) talked about the project and all the fun they had getting things assembled (rabbits eat stuff, in case you were wondering).
Our last stop was to the Antenna Assembly Building, where the 28th Antenna was hiding (and the 27th antenna was sitting). We got to walk around inside of that for a bit, looking up at all the feed horns sitting around. They also had the “Jack of Diamonds” sitting outside, which was the rail-mounted jack they use to move the antennas. You can tell you’ve hit the big time when you need a train just to move your telescopes. Pictures, as usual, are in the album.
Finally, we went inside the old cafeteria for lunch. The cafeteria, along with the Visiting Scientist Quarters (VSQ) are not really used anymore (the VSQ is going to get demolished some time), so we had boxed lunches. I forget what exactly I had, but I do remember that, having it at 1 pm after forgetting breakfast, it was very delicious.
After lunch, I took one last stroll of the area. I really wanted to see the ALMA antennas, so I walked over. I later learned that they weren’t so keen on people doing that, but my trip over prompted a mass migration of astronomers, so I’ll take credit for being a trendsetter instead of an instigator. ALMA, for those of you not in the loop, is the Atacama (Chile) Large Millimeter Array. The millimeters are not large in Atacama, mind you — it’s a large array designed to observe at wavelengths of around a millimeter. NRAO is working hard on it. It’s a big deal, really, especially during the conference. Also, I work in the ALMA wing, so I get to hear and see a lot about it.
Having finished up the picture taking, I got back on the buses, folded my arms, and fell asleep. I woke up about ten minutes from Socorro, having had my foot fall asleep on the bus footrest and my watch imprint itself on my arm (picture!). That was, more or less, most of the non World Cup excitement for the next week or so. Next blog post : EMRTec!
