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  • Boom 4:43 pm on February 22, 2013 Permalink | Reply
    Tags: astronomy, ,   

    Swiss Cheese, Statistics and the Early Universe 

    How could a fermented milk product riddled with holes relate to the cold space filled with hydrogen gas and stars, and to a branch of  mathematics that no one understands? The answer depends on how you look at the Universe. Regular readers may know that our colleagues in the Low-frequency Cosmology (LoCo) group here at ASU are building instruments to observe 21 cm spectrum of hydrogen from the early Universe. In a non-scientific description, we are trying to look at “rainbows” emitted by hydrogen gas using radio telescopes. The “rainbows” from different periods of time in the Universe also happen to fall into different frequencies of radio signal. Observing them at various radio frequencies will let us construct a cube showing the distribution of hydrogen in the early universe as a function of time. Now, emission from stars and galaxies breaks up hydrogen atoms surrounding them into nuclei and electrons, creating “bubbles” in which hydrogen gas is ionized, and there will be no 21 cm spectrum from within the “bubbles.” As a result you will see holes in the cube, like a block of Swiss cheese! I should also point out that the size of these “bubbles” can tell you what the stars that produce them look like!

    Unfortunately, our current generation of instruments is not good enough to construct a clean data cube that will let us directly look at the “bubbles” and measure them, and we will have to learn from statistics. Think about it this way: You count all the holes with a particular size or volume in your block of Swiss cheese. Then you chop up the cheese into pieces to “contaminate” them (be careful not to cut through the holes too much), then mix in small pieces of another type of cheese with tiny holes, like Tilsit, and randomly put all the pieces back into a block. If you then count the holes and measure their sizes again, the number should be relatively the same. (Remember that holes in Swiss cheese are big!)  This analogy does not exactly describe what  we will be seeing in our data, but it roughly explains what I meant by statistics. The bottom line is that you can still learn something about the Universe from bad data by using statistics.

    Figuring our what type of statistics to use and the best way to use them on the 21 cm data will be my Ph.D. thesis.  Please cheer and support me!

    Piyanat Kittiwisit, or Boom (as he likes to be called), is a graduate student in the Low-frequency Cosmology group in the School of Earth and Space Exploration at ASU. 

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  • raul_monsalve 2:38 pm on December 7, 2012 Permalink | Reply
    Tags: astronomy, chile, , ,   

    Southern Hemisphere Again! 

    Hey gals and guys!! My name is Raul Monsalve, Chilean, and this is my first post on the ASU Explorers blog. Just like the other contributors, I will show you some of the exciting things we do at ASU as part of the cutting-edge research endeavors.

    I am currently a Postdoctoral Scholar; my undergrad degree is in electronics engineering and my PhD is in Physics, where I worked on a CMB polarization experiment called QUIET. With that background, it is obvious that I like instrumentation for radioastronomy and that is why I am enjoying a lot working at ASU in the exciting field of Low-Fewquency Cosmology.

    As you know by now (especially with all the experiences shared by José in previous posts), astronomy is a discipline conducted at an international level for several reasons, and therefore if you want to join this field you will become a world citizen sooner or later.

    As an example, last week I traveled to Chile to a conference on astronomical instrumentation organized and hosted by the Chilean Ministry of Foreign Affairs and several universities. Being one of the most developed countries in South America, Chile hosts an important amount of world-class telescopes because of its clear skies in several frequency ranges. Among others, telescopes such as ALMA, E-ELT, GMT, VLT, CTIO, CCAT, QUIET, CBI, APEX, ASTE, NANTEN, ACT, POLARBEAR, TAO, CLASS, have chosen Chile to observe from. Astronomy is indeed becoming the focus of Chilean support in the R&D department.

    Some of the ALMA antennas at an elevation of 16,500 feet in the Chilean Atacama desert.

    VLT optical and infrared telescope at an elevation of 8,645 feet in the Chilean Atacama desert.

    During this trip I did not visit any telescope because all my time was devoted to the conference. It was the first meeting of its kind in the country, and had the purpose of introducing the efforts of teams from several universities working on instrumentation. Government representatives also attended in order to present the different financial instruments available for astronomy research. They stressed the fact that support has been increasing year by year, and encouraged (young) people to make use of it. Many Chilean astronomers, engineers and students attended, as well as internationally renowned scientists. This gave everybody the opportunity to network and broaden their perspective.

    I gave a talk the third day of the conference about what we do best: Low-Frequency Cosmology. It served as an introduction to the topic to Chilean scientists, and also proposed the idea of the participation of Chilean institutions in this kind of studies, possibly in collaboration with ASU. From people’s reaction, I can say that the talk and the idea were very well received, and that people from important institutions are very interested in participating. In that sense, the trip was a total success!!.

    My talk on low-frequency cosmology at the Chilean Ministry of Foreign Affairs, with part of the audience.

    Round of questions after the talk.

    Chilean government palace, “La Moneda”, in Santiago. The view is from the top of the Ministry of Foreign Affairs building, where the conference was held.

     
  • josemanuelchavez 4:32 pm on December 5, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Australia Recap + Deleted Scenes 

    These past two weeks have been the first of many things: first flight on American & Australian airlines (previously, I had only traveled on a Mexican airline) and the first time on a different continent.  We took one of the longest flights available and traveled to one of the most remote areas on Earth – which was precisely the point of this trip!

    One would think that this trip would show the vast differences between the U.S. and the ‘Land Down Under’.  Yet, I only noticed strong similarities throughout my stay.  Our flight over to Perth was akin to traversing the southern California countryside – plenty of discernible ranches with rambling roads along the way.  Other than the ‘Australian’ accent, which is not the same in all parts of the country, there aren’t too many disparities in the language.  I found the enunciation – with all its diversity – to be pretty awesome.  In contrast, it took me quite a while to get used to riding in the left lane – it’s like driving in a mirror image of the road!  Throughout the trip, I felt thoroughly welcomed and thrilled to be in a new land – scarcely feeling like a foreigner.  America and Australia are indeed siblings in the international spectrum.

    Another aspect of this trip that I enjoyed quite a lot was the fieldwork.  I have found going about the Australian outback, inspecting and mending instrumentation, to be incredibly fun.  It’s like playing in a giant sandbox that’s hundreds of square kilometers in size!  Yet, whether in the lab or a remote radio quiet zone, once you’re focused on what you’re doing, you quickly lose track of the setting.  In the field of astronomy, the entire world – nay, the entire universe – is our lab.

    Throughout the trip, I have observed the problem solving tactics of the other team members. With three PhD’s and a highly experienced technician constantly nearby, there’s always something to be learned.  I have noted their pedagogical tips and hope to apply what I’ve learned to tackle new problems.

    (One of my favorite quotes: “Don’t be a ‘guess-and-check’ engineer.  Be a scientist and solve this problem.”)

    From one west coast to another; a symphony of domestic and international flights, it has been a privilege and a pleasure to be your liaison throughout this trip.  Until next time, I hope you may again choose LoCo Airlines to reach your destination.

    Cheers!

    -Jose

    ________________________________________________________________________________________________________

    Deleted scenes:

    Foggy LAX

    Foggy LAX

    The behemoth that got us to Sydney - Boeing 747.

    The behemoth that got us to Sydney – Boeing 747.

    Our onsite LoCo engineer, Mr. Lizard.

    Our onsite LoCo engineer, Mr. Lizard.

    ASKAP radio telescopes aka giant mushrooms

    ASKAP radio telescopes aka giant mushrooms

    Always have a notebook handy - whether at the MRO or Mars.

    Always have a notebook handy – whether at the MRO or Mars.

    The team's glamour shot.  We come in peace.

    The team’s glamour shot. We come in peace!

    Giant sandbox

    Giant sandbox

    Caught me off guard

    Caught me off guard

    Like a kid in a candy store.

    Like a kid in a candy store.

    Representing the Sun Devils

    Representing the Sun Devils

    No gang signs please.

    No gang signs please.

    MWA core

    MWA core

    'roos on the run

    ‘roos on the run

    Go Devils! (I'm starting to sound like cheerleader aren't I?)

    Go Devils! (I’m starting to sound like cheerleader aren’t I?)

    On top of things.

    On top of things.

    This guy is a 24/7 explorer!  He creatively tied his camera to the end of a shoelace and fished a few shots inside a small cave.

    Hamdi is a 24/7 explorer! He creatively MacGyvered his camera to the end of a shoelace and fished a few shots inside a small cave.

    Don't get alarmed, it's just a flying camera riding on a kite.  No big deal.

    Don’t get alarmed, it’s just a flying camera riding on a kite. No big deal.

    Shh...

    Shh…

    Can you spot the emu/s?

    Can you spot the emu/s?

    Windy coast at Geraldton.

    Windy coast at Geraldton.

    Oh hey, there's the Opera House!

    Oh hey, there’s the Opera House!

    Until next time, Sydney!

    Until next time, Sydney!

     
  • josemanuelchavez 2:44 am on November 28, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 5.2: Ariztralia 

    As we finish our fifth day in Australia, I am set with mixed feelings.  On one side, we are essentially done with most of the work that our trip was designated for.  On the other, we are a day closer to leaving this amazing country – which feels just like home, sometimes even better.

    View from the breakaway

    View from the breakaway

    We’ve stopped by the control building and Boolardy Station for the last time.  We are extremely thankful for their hospitality and assistance.  The food was simply second to none; the staff was extremely supportive and constantly let us borrow equipment (we made sure to hand everything back) while teaching us more about the Australian culture.  Lou and I practiced speaking bit of Mandarin on site, I’m sure it had been months since either of us had done so with another speaker.  It’s important to note how useful the control building was.  It has been, in many ways, our home base.  Let’s put it this way, if we were astronauts in near-Earth orbit, it would have been our ISS (International Space Station).

    Arriving at Geraldton

    Arriving at Geraldton

    After a four hour drive, we arrived at Geraldton.  A small resort town, it is right on the coast facing the Indian Ocean.  It’s been years since I’ve smelled the salty air; pleasant gusts of wind are constant reminders.  I’ve never been in this part of the world, yet it feels awfully familiar.  Tomorrow we will depart to Perth and then onto Sydney.  Cheers mate!

     
  • josemanuelchavez 9:51 pm on November 26, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 5.1: Flying Cameras 

    Hello all!  Today we woke to another amazing breakfast and headed off to the MWA site.  We toured through all the tiles and climbed the nearby breakaway.  For the first time in the trip, we finally got some pictures of some kangaroos (or rather, “roos”).

    'roo radio explorers

    ‘roo radio explorers

    We then returned to the DARE/EDGES to take a final view of the set up. Lou, one of the MRO staff, let us borrow a compass which we used to measure the angle of the DARE antenna from North.  As he told us, this area has very little magnetic interference which helps us get very accurate measurements.   The angle was found to be about 19 degrees off.

    While part of the time was wrapping things up, Danny and I attached a camera to his kite and took aerial footage of the site.  After a couple of failed attempts, we finally got the kite to fly consistently and saved the video.

    Test run of the LoCo KiteCam

    Test run of the LoCo KiteCam

    Aerial view of EDGES

    Aerial view of EDGES

     

     
  • josemanuelchavez 9:30 pm on November 26, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 4: It's LoCo Time! 

    G’day mates!  It seems like the Australian dialect has finally caught up to me.  With most of the fieldwork complete, we reviewed the glorious amounts of data that DARE/EDGES had produced.  Nothing alarming came up during the day, so we decided to stay in the homestead and organize our gear for our transit back home.  Truth be told, it was quite a good thing to stay in today, given that it was considerably warmer than the previous days.

    Representing ASU

    Part of the team went to Mullewa to pick up the new addition, Dr. Danny Jacobs.  Bringing new energy and supplies (a filter), Dr. Jacobs was promptly updated about the team’s work.

    Hard at work

    We are planning to go out (briefly) to the field again tomorrow.  The agenda is to measure the orientation of the DARE and EDGES systems  and to run a few more tests on the DARE receiver.

    Site satellite view

    It’s important to note about the warning that everyone who visits the MRO will gain weight.  Skeptical at first, I would like to conclude that this is in fact, true.  Imagine being offered multiple, delicious meals throughout day – there is simply no way to say no.  The perfect example is the local yellow lab who has been at Boolardy Station for a few years.  He happily trots around the encampment, taking breaks along the way, and nibbling on unidentifiable crumbs.

    Monty

    Today will be our last day here, we will depart tomorrow afternoon to Geraldton and onto the MWA meeting.

    With busy schedules, almost always something on the agenda, and families in different time zones – one often looses track of time.  But when asked what time it is, we respond: “It’s LoCo time here!”.

     
  • josemanuelchavez 5:59 pm on November 25, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 3.2: Divide and Conquer 

    Mid-morning we had “smoko” (coffee break) – a delicious coconut cake with a sweet lemon frosting. Hamdi has become a huge fan of the butter out here (as he says, “MRO has the best butter in the world!  I am an MRO guy!”), so one of the MRO staff, Mike, brought Hamdi two bricks of butter for his smoko. However, we couldn’t convince Hamdi to eat that instead of the cake…

    Hamdi with his butter

    Possibly enthused by all the sugar, the team embarked to the field, ready to engage DARE/EDGES yet again.  Once at the site, Judd split us into teams: the A Team would deploy the EDGES receiver to a run a few tests while B Team would glue the DARE’s foam housing back together.  Not unlike a couple of special operations units, we performed our duties.  (Maybe next time we could do a parachute jump and land directly on site.)

    Inspecting the EDGES system in the control building

    Hamdi and I focused on running a few tests on EDGES, starting off by measuring the impedance.  We had to layout what seemed like elvish rope’s (Lord of Rings reference anyone?) worth of Australian extensions cables between the hut and the antenna.  In order to weatherproof the antenna, the team thriftily covered the receiver with a plastic bag and laid down an adhesive cover across the upper slits of the antenna.  With this complete, we took a sample of the spectrum and verified it looked comparable to a previous measurement.   Oddly enough, being able to see just a little RFI helped us validate the spectrum measurement again.  Spotting one of these man-made signals is a reassuring token that the antenna is functioning properly.  For example, occasionally detecting a spike around 120 MHz means that an airplane might be flying overhead.  With this healthy indication, the team left EDGES recording overnight.

    Running tests on EDGES

    The B squad directed their efforts to fortify DARE.  They had to make efficient use of the glue on hand, carefully positioning glue pellets along the along the walls.  Even the distinctive “scarred” side of the enclosure seemed to have healed well.  Not a field for the faint of heart, radio instrumentation sometimes proves injurious for interloping spiders and foam boxes.

    Tying down DARE

    Having received positive results and stabilized the devices, the team drove back to the homestead with a considerable weight off its shoulders and off the truck bed, literally.  We had less stuff to take with us – not as much to worry about.  Depending on the quality of data, we might not return to the site tomorrow and instead spend time analyzing the data.  All indications suggests that both experiments are being team players and producing splendid results.

    Discussing the preliminary data

    Rested and washed up, we had an amazing roast beef for dinner.  Complete with a side of bread, non-skinned potatoes, peas, and squash – a feast for champions.  Moreover, Hamdi finally caught up with his daily consumption of butter.  Slowly but surely, he conquered the golden cube – the reward of a day’s hard work.

     
  • josemanuelchavez 12:00 am on November 25, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 3.1: Up and rrrrruning 

    On day three of this journey, the strategy was to place the DARE antenna back inside the foam box.  Sure enough, as soon as we had placed the antenna back on the foam supports, Hamdi noticed that one of the antenna terminals was broken.  This meant that we needed to re-solder the joint together.

    Inspecting the DARE system

    Rather than risk moving the antenna again, we constructed a makeshift lab in the outdoor desert so we could solder the joint in place.  Hamdi promptly began soldering in a meditative style that would have made his yoga instructor proud.

    Balancing stick position

    Once the terminal issue was fixed, the team did a quick spectrum measurement from 1-300 MHz in the hut.  We noticed that it looked considerably different.  There was plenty of power from the sky!  At first we thought the RFI look suspiciously low.  Although we are in a RFI-low area, there is still a small trace of things that we should see in the spectrum – such as occasional Orbcomm transmissions at 137 MHz.  After waiting a few minutes, we did indeed see these signals.

    Field lab

    It’s also nice to note that today has been considerably cooler than the previous days.  The wind helped keep the flies away and the pristine clouds were very welcomed.

    Hamdi proceeded on to taking a total power measurement.  First with the antenna connected and then with the load.  The input connection was connected to a splitter, which splits the signal in half.  We then have to compensate for this by adding 3 dB to both signals.  We recorded the total power produced by DARE when using the antenna to be -24.64 dBm and the load to be -28.46 dBm.

    DARE with our hut in the background

    With roughly half a day’s work already completed, we’ve analyzed some of data back in the control building. After a refueling lunch, we’ll go out again and wrap things up.

     
  • josemanuelchavez 9:19 pm on November 24, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 2.2: Smoko Loco 

    After spending a few hours in the field continuing our efforts on DARE, we decided to take a break, or rather a “smoko” in the local slang.  Normally referring a smoke or tea break, the team bent the meaning to imply a rest from work (maybe some tea).  On a related note, Hamdi’s new rap name is “Smoko Loco”.  We have yet to see if the name will launch the aspiring rap artist to super-stardom.  Stay tuned.

    Hamdi making sure the spectrum analyzer rides comfortably on the way to the site

    Nearby the EDGES/DARE site there is a control building that has a well-equipped lab in addition to some other amenities that one would find on a campus research building.  Along with having a kitchenette and conference room, it also has a designated First-Aid base and a highly monitored wing with dozens of (yet to be) servers.  In order to prevent any RFI (Radio Frequency Interference), the building is protected by two pairs of pneumatic doors.  This makes the building an impenetrable and impermeable signal fortress.

    Set of pneumatic doors

    Hamdi continued working on the system in the lab inside, seemingly running off infinite energy.  After a few tests, he alerted us by calling out, “I found the problem!  It’s alive!”, referring to the balun unit.  The unit was difficult to measure, but by boosting the signal we were able to spot it on the spectrum analyzer.

    Hamdi using the spectrum analyzer

    As the team discussed during the lunch break, unraveling low-frequency radio electronics is not a simple task.  For instance, to use commercially available equipment we must use a single-ended component.  The team uses balun circuits to transform this to a differential (or vice versa).  Test equipment we have on site does not measure differential circuits directly.  This means we need to use some tricks.   Likewise, faint signals provide a problem which requires highly sensitive equipment.   In the end we measured the gain of the balun at 14 dB with an open load.  That sounded about right, so we were ready to reinstall the balun and the antenna.

    Control building

    Refueled and regrouped, the team launched off from the control building and back to DARE.  The winds had beefed up considerably in the afternoon, which made housing and rearranging the somewhat fragile DARE biconical antenna worrying.  So we decided to postpone until the morning.  Comfortable with a good day’s work, the team used the hut as a temporary home for the antenna and strapped down the foam enclosure.

    DARE securely strapped down, dubbed “Scar Face”

    All in all, the team managed to solve a few issues – technical and logistical, alike.  We checked the DARE low noise amplifier, learned how to best arrange our day, and many other things that will help out as a whole.  The team definitely felt more confident after today’s work.

    View outside the control building

    I do have to add that being here reminds me of my childhood summers in Mexico; a foil between scientific investigation and the rugged rancher lifestyle.  The people are both relaxed and excited about spending time at Boolardy (or rather Ball-ah-dee) Station.  It’s a great place to do research and meet pleasant people.

     
  • josemanuelchavez 12:32 am on November 24, 2012 Permalink | Reply
    Tags: astronomy, , , , ,   

    Day 2.1: Ready to Roll 'n' Rock 

    On the second day of our problem solving expedition, we began our morning earlier than usual.  Given that we had arrived to the site pretty late the day before, we wanted more time to address the problems.  We were ready to rock ‘n’ roll, or as Hamdi put it “roll ‘n’ rock”!

    Hamdi testing the EDGES system

    It took us longer than expected to get going from the Boolardy Station this morning because Hamdi was repeatedly examining the EDGES receiver unit while continuously saying “just one more thing”.  It’s important to note how easy it is to lose track of time when you’re thoroughly focused on finding a problem.  There was some bouncing of ideas on the way to site, which ended in Hamdi betting his lunch that the problem was related to temperature.

    Arriving at the DARE site

    We promptly arrived to the site once again, primarily focusing our attention to DARE.  The method of attack was use metal plates (that had a previous life of being cabinet dividers) to pry open the DARE enclosure. Unfortunately, this didn’t work as we had hoped.

    Referencing previous pictures

    Given few options left, we finally went with the contingency plan of cutting the top off the DARE enclosure.  With an image from a prior trip of how the antenna was positioned inside the enclosure, the team carefully made some horizontal incisions across the foam and raised the top portion of the box, opening the system for inspection.  Tragically, a spider was injured during this process – we hope that it is doing well.  Before we altered anything, Hamdi made sure to take a spectrum sample to use for later references – like yesterday, it’s always important to record what happens before you change the system.

    Opening up DARE

    Nostalgically remembering his time working in Goldstone Observatory, Hamdi expressed that he was excited to be tackling this problem despite the pestering flies and steady heat.  With a spectrum established from 1 to 200 MHz, the team expected to find a change in the amplitude of the signals.  We then proceeded to examine the antenna itself.  We also used a total power meter to measure the power connected and disconnected to the antenna.

    Dust Devil

    With less sun but more flies, our second day has produced a bit more results than the first.  The fieldwork here has proven to be substantial but we realize that all the efforts ultimately turn into both fun and challenging experiences.

     
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