If you can't see through it ... ski through it

Easter sunrise behind the telescope.

Easter Sunday was quite non-traditional for me, but memorable nonetheless.  Actually, we had great weather for observing, and I made a lot of progress with my final observations, which ran from 5 am to 12 pm.  However, the previous couple of days hadn't been so good for observing, and I had spent some time staring out the window at clouds, snow, and skiers.  During that time, I vowed to ski before I left IRAM.  Finally, on Sunday, at 2 pm I hit the slopes!

View from the top.  Three things that I love in life: telescopes, mountains, and skiing.

I borrowed skis and boots from the observatory, which were probably older than I am, but fit almost perfectly.  I think you could call the observatory "ski-in-ski-out", because I just walked out the door near my room, clipped into the skis, and (after becoming re-acquainted with the skiing motions after more than a year of not skiing), I was gliding down the mountain.  Remember, it's April, which is definitely the end of the season here, so most of the snow seemed artificial, but at least well-groomed.  It was sunny and warm, and with clear skies, the view from the top was magnificent.

My transport down the mountain.

I returned to IRAM in the evening for a fantastic dinner, nice red wine, and good conversation with the other astronomers.  In the morning, the snow-cat took me down the mountain, and I'll spend the next couple of days exploring Granada.  A perfect ending to a very good observing run.  I can't describe exactly what IRAM was like, because the weather and conditions were always changing, and the contrast of the observatory on top of a ski resort in southern Spain's Sierra Nevadas is difficult to synthesize.  So, I will direct you to my photos, and these should give you some idea of my experience here.

Our only option to see the big picture

Perhaps you have read several of my previous posts, and I hope you have gotten some idea of why Chile is one of the best places in the world for astronomy.  For this reason, I have been thoroughly enjoying the experience (Thanks: Fulbright, U de Chile, ALMA, Yale) to live in Santiago this year, and work at the University of Chile and ALMA.  So why, you might ask, would I leave the astronomy-mecca that is Chile, and travel 7000 miles to seclude myself on top of this mountain in the Spanish Sierra Nevadas, where we happen to have been stuck in a snowy cloud for several days?

Sometimes we're above the clouds (at 3000 m elevation), and conditions are great for observing.  The sunsets are gorgeous too.

The telescope I am using is called the 30 meter telescope at the Institut de Radioastronomie Millimétrique (IRAM).  "30 meters" is the size of the telescope dish, and IRAM is an international research institute with headquarters in Grenoble.  Besides the fact that when I applied to use the 30m telescope, I was encouraged by the potential trip to Spain and a week of what I was told would be incredible cuisine, I wanted to use this telescope because it is one of the largest single dish telescopes that observes at the frequency at which carbon monoxide (CO) emits light.  This frequency of light is not necessarily what most people think of as "light".  If you looked at the CO in a star forming region with your eyes, you would see nothing, because the gas and dust are not hot enough to emit light at visible wavelengths.  However, the gas that forms stars is just barely hot enough (still, it is very very cool, only about 10-20 Kelvin, or degrees above absolute zero) to emit some radiation with wavelengths of about 1 millimeter.

They were actually observing through this.

 The IRAM 30m telescope is designed to detect this kind of light.  Why no shiny mirror? Don't you need a dome? How can you keep observing even when it's cloudy outside?  Radio and mm telescopes are slightly different than optical telescopes because the longer wavelengths of light don't need such a perfectly smooth, shiny mirror surface in order to be reflected and focused.  Also, the weather (as we obviously have wind, rain, snow here) doesn't do significant damage to the surface of the antenna.  And, we are lucky that we can observe even if it's cloudy or somewhat humid (although we have to be careful with the telescope if water, snow or ice accumulate) because radio wavelengths of light are longer than a typical water molecule, and therefore just pass right through (radio wavelengths can also pass through you and me, think about it).  Similarly, we can observe radio wavelengths during the day, because the light of the sun doesn't compete with our observations.  Very convenient... 

Check out these icicles on the telescope.  Skiers beware.

In fact, ALMA is also a "mm/sub-mm" observatory, and it can detect similar emission as IRAM.  But, the IRAM telescope is 30 meters, and the largest ALMA antenna is 12 meters.  With its many 12 meter antennas, ALMA has a large "collecting area" (think of it as many buckets scattered through the desert collecting falling photons), and it is very sensitive to faint light.  This is because the sensitivity of a telescope depends on its size, and with an array, the areas of all of the antennas contribute to the total sensitivity. 

Another important concept in observational astronomy is that the spatial scale to which a telescope is sensitive depends on the distance between any two points of the telescope.  In other words, an array of telescopes with large distances between any two telescopes (a.k.a. baselines) is sensitive to very small details. However, it is difficult for an array like ALMA to also be sensitive to the larger information (they don't want the antennas too close that they might collide).  For this we need single dish telescopes, where we can consider the infinitesimally small distance between any two contiguous points to tell us the bigger picture of what we are observing.

The receiver, behind the telescope dish, is where some magic happens.  Millimeter-wavelength light is converted to a frequency that a computer can process, and we can measure how much light we have received.

The heavy lifting (i.e. moving the telescope) is done with monster motors like these, inside the telescope mount.

Eventually, ALMA will incorporate a "compact array" and several single dish telescopes, at the same time as it functions as a large array that spans several kilometers, and we will have the best of both worlds.  But, for now, there is a bit of an art to carefully combining observations from a telescope array (we used an array in California called CARMA) and a single dish telescope like IRAM.  This combination magic will be my project after my observations end, so that hopefully we can make a pretty picture, and even more importantly understand the details of star formation on many levels. 

Cloudy and clostrophobic, but content

The amount of ground I covered getting here will soon be balanced by the amount of ground I cover each day.  That is to say, once you get to the telescope, there's no reason even to leave the building.  The commute to work involves two flights of stairs, and a short hallways.

I spent the last couple of days preparing my observations, and then learning how to observe with the IRAM 30m telescope.  Up to the last minute, we were deciding on a few crucial details of the observations.

One important piece of information for your observations is known as an "off-position", which is a position in the sky that you think will have very little (preferably none) light compared to your target source (at whatever wavelength you care about).  This way, whatever emission you do get from the off-position, you can assume is coming from the fluctuating atmosphere, and therefore correct your observations. Sometimes you just have to take a shot in the dark, or make an educated guess based on previous observations.

The other last-minute decision had to do with what's called "spectral resolution" of the observations.  You have a choice of how much detail you want to see, in exchange for the breadth of information you receive. Ideally you'd get both, but you can't have your cake and eat it too (an aside: they do feed us very well here, and that means multiple desserts every day).  The receivers needed to be precisely tuned to the specific wavelength(s) of interest, and if we tuned with very fine precision, we would lose some efficiency.

Fortunately, this is a very conducive work environment, with limited distractions, so I was mostly able to focus on the task at hand.  But, I occasionally caught myself peering out the windows at the changing weather conditions, and the occasional skier passing by.  And then I realized, I hadn't been outside in more than a day.  Some part of me thought, "Cool, maybe you should take the challenge, stay inside for a week straight, just to see what it's like."

It's totally feasible here, because we have accommodations, a kitchen (and wonderfully talented cooks), recreation facilities, and (of course) work, all in the same building, which is even connected to the telescope by a below ground passage. But, knowing that I'm atop a mountain at about 10000 feet elevation, overlooking the southern Spain Sierra Nevadas (even though we've been stuck in a cloud since I arrived), I just can't give into a silly challenge to stay inside the whole week.  I have to explore, I miss the feeling of sun and snow and wind on my cheeks.  So, at least I ventured outside for these photos...

At first it was so cloudy that I could hardly see the telescope.

The telescope sometimes appears to be peering towards the skiers as they come off the chair lift.

An older, smaller telescope is on the next peak.

Finally the clouds parted for a beautiful sunrise over the ski area below, and signalling the beginning of fantastic conditions for my observations.

20 hours

The past approximately 20 hours have been chaotic, but at least they have been linked by one common theme -- transportation adventures, with everyone else acting like it's all completely normal.  Here is the recap of the highlights in my journey to observe at the IRAM (Institut de Radioastronomie Millimétrique) 30 meter telescope.  The irony is that I will be using the telescope for a total of 20 hours over 3 days.

The adventure begins on board an Iberia plane, recently having taken off from Santiago, when it was announced that we would be arriving in Madrid at 8:00 am. Our itineraries said 7:00 am, and to complicate matters, the three others in my row and I had connecting flights at 8:00 am.  When one of the women (luckily the others spoke Spanish, and could vouch for me) asked the flight attendant how we would make our connection, his answer: "That will be difficult."  I told myself at that moment that there was no use in worrying for the entire duration of the 12 hour flight, and in the back of my mind I kept hoping that maybe the wind would carry us just 10% faster than expected.

Granada is in the Andalucia region of southern Spain.

We landed at 8:00 am, as announced, without one mention that we were later than the original itinerary.  Still holding out hope, I jogged through the Madrid airport, through immigration (luckily it was quick), and boarded the shuttle to the K terminal (the sign said it would take 18 minutes, but I kept optimistic).  All for nothing, because by the time I arrived at K, the flight wasn't even listed on the "Departures" screen.  Luckily, my half-marathon training had paid off when it counted the most, and I arrived near the front of the line at customer service.  Actually, it was very easy to switch to a later flight, I just passed my failed boarding pass across the counter, and without hardly a word, the Iberia employee gave me a new ticket for a later flight.

The problem was that my plan for transport to the telescope relied on the 8 am flight, to arrive in Granada at 9 am, and immediately take a van to the telescope (they had actually made special arrangements for me).  I found the words in Spanish to sheepishly say "I missed the flight", and I called the telescope to tell them I'd be later than expected.  From here, the adventure takes a turn for the better.  Beginning with the fact that people in Spain speak slowly and clearly, and I could actually communicate when it mattered the most. 

These bull cut-outs are seen all over the region.

I did arrive as per the revised schedule at 1 pm, took the transport to the observatory offices in downtown Granada, and from there a van about 1 hour to the Sierra Nevada ski area.  Slightly jealous of the skiers who will be enjoying their vacation during Semana Santa (Holy Week), but also realizing what an awesome experience it is to go to a telescope, I boarded the gondola (yes, everyone else was carrying skis, and I was carrying my luggage) which took me to the next ski station.  From there, I loaded myself and my luggage into a snow-cat, and we headed up the ski slopes to the telescope which perches on top of the hill.  That's right, next to a chair lift! 

Not my photo, but that's the telescope and our transportation.

The whole time, at every junction, the person accompanying me just waved me on to the next (progressively more strange) mode of transportation, as if (1) it was obvious that everyone rides a gondola to work sometimes, and (2) of course there's a gigantic 30 meter telescope sitting on the ski slopes.  And I went along with it, enjoying the ride, and looking forward to what will certainly be a unique Semana Santa.  It took 20 hours to arrive, who knows how many to return.  I hope the 20 hours of observations are perfect.

Turno #3 diversions

This turno got off to a delayed start, following an intense rain storm at the ALMA OSF (we hesitate to boast that this is the ``driest place in the world'' now).  Last week, the previous astronomers on shift were sent home early, and our trips were originally cancelled, then rescheduled a day later.  This meant that when I arrived at the OSF along with my supervisor, the first night we worked hard to quickly get the system going again and as many antennas as possible reinstated into the array.  Fortunately, the weather continued to improve throughout the week.  I hope this means the end of this year's "fuerte" (strong) altiplanic winter. 

After the rain, the mud dries into the most impressive formations I have ever seen (this is a parking lot that became covered in mud/dirt).  As the water evaporates, the sheets of mud crack and curl upwards around the edges.  A fun diversion can be to toss sheets of mud and watch them shatter into dust.  I have seen sheets several inches thick, and several feet long!  The desert is an amazing environment.

Each of the following nights, we had more and more antennas becoming available.  For various reasons, the array is always changing.  In this case, some antennas were being powered up after the storm, and others were being moved to a new configuration (unrelated to the storm).  To keep the telescope operating at very high precision, we need to know the exact location, focus, etc, of each antenna, and this process of measurements (called antenna integration) takes some serious time and attention.  Luckily, I was working with a good team and every night we made progress.


It wasn't always business as usual during this turno.  Here are a few notable distractions that kept things lively. 

Seen around ALMA -- The first is a video taken by the Project Scientist, just to show you that some creatures manage to survive in the harsh desert environment.  Creepy creatures like this one seem to do okay here.  Annoying flies and mice also call the ALMA site home. 

Visitors -- The ALMA Education and Public Outreach officer seems to stay busy coordinating visits to the ALMA site for journalists and photographers.  This weekend, we saw several new faces in the control room, including journalists from USA, France and Germany.  Of course, we had astronomers from, you guessed it, USA, France and Germany to talk with these visitors!  At first I was hesitant to be the USA voice for ALMA, since I too am only a visitor here.  At least I got to tour the North American antenna camp along with the journalists, and we saw one of the antennas being delivered by the transporter.  But, in the end, talking with the journalist made me even more excited about the project, especially the parts of this project that have never been done before, and it reminded me how fortunate I am to have this opportunity to work here. 

Also visiting ALMA was a photographer sent by ESO (European Southern Observatory) who is documenting telescopes for a book to celebrate the 50th anniversary of ESO this year.  He was photographing a group of us huddled around a computer that was controlling the antennas -- what we were doing could seem like a dull task, but actually it's exciting to be working with such a diverse group of people on a project that is always new.  One evening, we gathered a group outside for a photo with the sunset, and with Jupiter and Venus over our shoulders.  We were from Chile, USA, Japan, and Europe, personifying the agreement of the ALMA project. 

Getting outside -- We work a lot at ALMA, many hours spent in the control room staring at computers.  And while we accomplish a lot in that control room, I try to remember to also enjoy the incredible surroundings.  In all directions from the ALMA OSF are incredible views -- exploring around the ALMA site by day, or looking up at the sky at night. 

I went on two hikes with guys who work building antennas for ALMA, and who know the site very, very well.  We headed out walking north of the OSF, towards a giant cactus, and descended into a deep canyon that seemed to drop out of nowhere.  We followed the canyon as it wound through the nothing-ness, sometimes scrambling over boulders or hugging the walls of the rocky canyon to descend deeper.  To complicate matters, we had to avoid some pools of water after the recent rains, and the accompanying mud which always seemed to be some unknown consistency.  Fortunately, my new friends helped me along the way, I stayed dry and fairly mud-free, and I learned some more about the area, and about hiking in canyons (i.e. never go down somewhere that you may not be able to get back up).  I look forward to exploring this area even more.  Of course, next time I show up to our daily meeting after returning from a mid-day hike, I will make sure that I have cleaned the sunscreen and dirt off of my arms first…

Many years must have have shaped and rearranged the rocks in this canyon, like this boulder that we walked under.

It's not only the landscapes that are amazing here, but of course the sky is also impressive and infinite.  Last night one of the guys here set up a small optical telescope outside and we took a tour of the southern sky.  The highlights: a nebula in the Large Magellanic Cloud, a star cluster, the Sombrero Galaxy, the Orion Nebula and Saturn (okay, the last two are not uniquely southern, but they are especially awesome with such a clear sky).  We had spent several nights observing Saturn to calibrate the ALMA antennas, and to an ALMA antenna, Saturn is best seen as a spectrum with a little blip of light to signify a detection of the planet.  Exciting to us astronomers because it means the antenna is working.  But, not very aesthetically intriguing.  Last night, through the optical telescope, Saturn was more awesome than I have ever seen.  The rings were perfectly oriented, and we could even see the gap between the ring and the planet, several bands on the planet, plus several moons to the side.  It's good to remember that at its very essence, our research is really beautiful and somewhat mysterious, I think this keeps us motivated to continue exploring the universe. 

This photo of Saturn was taken with a camera pointing to the eyepiece of the 8-inch Celestron telescope. You have to see it to believe it.  Photo courtesy of an ALMA co-worker. 

Astrobites Post: An antenna array is a successful mix of apples and oranges

Here's my latest astrobites post, with some more details about the incredible ALMA antennas.  You'll learn about submillimeter interferometry, and why the 66 antennas at ALMA, built and operated by an international collaboration, make this the largest astronomy project in the world.

Did you know that the ALMA Array Operations Site (AOS) technical building is the second highest steel frame building in the world, at 5000 m?  If you can tell me what is the highest, I'll be really interested!

Real weather, simulated observations

We're nearing the end of the altiplanic winter here in the Atacama, which means (fingers crossed) we should get back to observing soon.  The other night we were very productive with observations, but last night was somewhat of a different story.  Snow at the array meant we were shut down for the night, limited to running the antennas in "simulation mode", which means we can test the software and the observing scripts, but the antennas only pretend to be observing (they're not supposed to actually move if there might be snow/ice on the surface).  So, the weather wreaked havoc on the observing plan, but it did bring some pretty dramatic (and admittedly incredible) scenes in the afternoon.  I tried to document it all.

(1) Sand storm -- In the time it took me to walk from my room to the control room, the sand storm blew by, probably about 10-20 km, which means it was moving about 60 km/hr (from my very rough estimates).  It fortunately didn't arrive all the way to the OSF (fortunately, because I hear the sand is impossible to dislodge from your ears, face, clothes, etc).  I wanted to capture the whole scene, because to the north was a thick cloud of sand, but to the south was still sunny and clear.  Above is the 360 panorama I patched together.  If you google something like "Atacama sand storm", you will see that this must be rather common after all, and produces plenty of intense scenes.

(2) Rain(bow) -- Every time it rains here, we head outside, just to feel the cool moisture on our skin.  Someone usually comments about how this should be the "driest place on earth".  Well, it did rain here, but it passed in less than 5 minutes.  Clouds in the direction of the antennas is not a good sign for the night, but at least the rain left behind a full rainbow.

(3) Cloudy (bad) sunset (good) -- Again, astronomers may regret to say that some cloud cover produces the most gorgeous sunsets.  Well, if we can't be observing, at least we can appreciate the beauty.  Here I was enjoying the sunset with one of the other astronomers on shift. 

(4) Snow vs. antenna -- An antenna makes the ~30 km journey from the OSF (3000 m elevation) to the AOS (5000 m elevation) very slowly and carefully, aboard the specially designed antenna transporter.  Any sign of weather, and the move is cancelled.  This afternoon, along with all of the other crazy weather that blew in, some snow arrived at the high site before the antenna, and the transporter was forced to turn around.  We (the astronomers and array operators) at least made lemonade from the lemon-y weather, and hung around to enjoy the show as the antenna was returned to its temporary home near the control building, where it will wait out the bad weather.  Check out more photos (uploaded on Picasa), and the video I took, but maybe it's better in fast-motion.  In case you're interested, the transporter has 28 wheels that can move independently, and can place the 100 ton antenna on its station with 1 mm of accuracy!!  The driver makes most of the journey in the cab, but for the final moves, the transporter is operated with a remote control (it seems sort of like a really exciting video game).   

... All of this exciting weather ultimately shut us down.  These were the most "real" things that happened, all within about 1 hour this evening, before we headed inside for the night of observing in "simulation" mode.  So, enjoy the photos and the dramatic stories now, and I hope that I won't have anything more to report of this nature in the future!!