Tagged: astronomy Toggle Comment Threads | Keyboard Shortcuts

  • kdavis32 7:53 pm on December 7, 2015 Permalink | Reply
    Tags: antarctica, astronomy, STO-2   

    STO-2 Progress Update 

    The STO-2 mission has been progressing remarkably smoothly (mostly!) as we prepare for launch later this month. The instrument team, APL gondola team, and NASA Columbia Science Ballooning Facility have all been pushing hard to make this mission a success.


    Pointing testing looking at the sun outside the balloon hangar. 


    Chris Groppi assembling an instrument package to run the 4.7 THz camera.

    On the instrument side of things, the Ball dewar that holds our camera pixels was filled with liquid helium last week. We were able to test the camera detectors once this was done, because the camera will only work at these temperatures. We have 100% of our pixels working at all 3 of our target frequencies! We were able to align all of the cameras properly with the optical system and our Local Oscillators (light pumps, which you can read more about in my previous post here) while the dewar was on the work bench. The alignment took several days and several new bolt holes, but we managed to get everything running perfectly in the end.

    One of the things I am helping with is making sure that the camera detectors are pointing straight out of the dewar window and aren’t tilted to the side. One of the easiest ways to do that is to have the camera take a measurement while looking at a hot and cold load in front of the window, and comparing the input power while looking at the two temperature loads. We used the room temperature (~300 Kelvin = 68 F) paddle on a spinning wheel as a hot load and the bottom of a cup of liquid nitrogen (77 Kelvin = -321 F) as the cold load.  This ~400 degree temperature change causes a significant change in power received in the camera, which we use to measure the sensitivity of the camera towards a given direction. We scan the cup and paddle system in front of the window to find where the strongest signal from the cold load is, and determine if that is in the center of the window or not.

    Once the instrument pointing, noise measurements, and alignment had passed our preliminary tests, we moved forward with the next major progress milestone of putting the dewar underneath the telescope. This involves taking the telescope out of the ‘cradle’ or gondola structure and attaching the dewar to the bottom of it, and then putting the integrated system back in the cradle. Once it is attached, the telescope needs to be re-balanced and tested to make sure that it can tilt and swing without any interference. We were all nervous to see the dewar tilt over, but we had no leaks. We had one electrical problem but it was resolved quickly without costing us much time with our schedule.

    naked telescope

    Kate and Jim look over the telescope (left) and cradle (right)

    OMG telescope is naked

    Telescope with the dewar attached underneath. 

    Over the next few days, we will be testing the focusing of our telescope. It is more challenging to focus the telescope than you would expect because the humidity in the atmosphere on the ground absorbs light at the frequencies our instrument can see. We are getting around this problem by using transmitters at a different frequency than our instruments normally use, but can still see.  Also up next will be more pointing and alignment tests, installing the communications packages, installing the solar panels, and another hang test. Stay tuned!

  • tmozdzen 10:12 pm on July 20, 2014 Permalink | Reply
    Tags: , astronomy, , , ,   

    Nevada Field Trip, Day 5 – One Last Low Band Reading and a Steak Dinner. 

    The weather report for our last full day at the ranch indicated afternoon showers, but clear in the morning until about noon. We decided to get one last 2 hr low band measurement taken in the morning. On our way back the previous day, we noticed a spot 15 miles south of the ranch that looked favorable.

    As we loaded the car, the tire pressure indicator warned us that we were low 5 psi in one tire. We exited the car, had a look, and discovered it to be worse than just 5 psi. The tire was half flat.

    Luckily, John and the ranch hands had not gone into the field yet and were still working in the area.   So we asked them if they could help us with our tire. They pumped it up with air and then we easily heard where the leak was – on the bottom of the tire right in the middle and was caused from hitting one too many sharp rocks. The tire couldn’t be patched, it was a dead tire.

    John knew of a tire repair place in Austin, Nv, just 50 miles away. The man had a tire our size, and agreed to come up the road from Austin to deliver and install the new tire (actually a used tire). The deal was on.

    Raul and I drove to our observation site using the spare tire (not a full sized spare) and began setting up the morning’s observation. 10 minutes later, the repair man pulled up with his truck and proceeded to take care of our tires. Amazingly the whole ordeal only set us back about one hour. We thanked him profusely and paid him profusely, but it was worth it. He said, “this is my job, I fix tires.” And he was a very busy man indeed. He was one of the tire shops selected to patch the huge tires for one of the mining companies. He told us that those tires were very lucrative to repair.

    The sky was clear when we started but we knew it was going to be a race against time. Hour one: completed. Skies looking a little more ominous. Hour two of measurement began: how long would the sky hold off? We waited a bit too long and the high winds came. We furiously tried to shut down the computer cleanly, but the wind and now rain droplets were coming down too fast. Our shade structure twisted into a pile of rubble. We did manage to get the computer and instruments back into the car with no damage to them or us.

    We unpacked the car at the ranch, as it had not started to rain there yet, and repacked it properly. That hour of delay from the flat tire did cost us as we really needed that extra hour.

    As we were recovering from the earlier mayhem, the AC suddenly shut off and all was quiet – the power went out. OK, what next?! Fortunately, dinner was being cooked on the gas grill and we would not be denied our dinner.  In the meantime, I went down to the hot spring hoping to cool off.  The end of the pond away from the spring was indeed cool and it felt very nice to wash the dust off and cool off in the hot spring (luckily we are from Phoenix and have an altered sense of hot and cold).  Showers at the cabin were out of the question as the cold water was too hot to stand under.

    We had a very nice dinner with the ranch manager John, with his wife, two daughters, the daughter’s 3 little boys (ages 3, 5, and 7), the daughter’s boyfriend (also the head ranch hand), and one college intern.  We had great discussions about cattle, the history of the ranch and surrounding area, and of course, John wanted to know more about the topic we were studying.

    And to cap off dinner, the power came back on after being out for nearly 6 hrs. The day had a rough beginning, but a pleasant ending.

    We are now headed back to Arizona and are examining the data we collected.

  • tmozdzen 9:27 pm on July 20, 2014 Permalink | Reply
    Tags: , astronomy, , , ,   

    Nevada Field Trip, Day 4 – The Search Continues, but Nevada has a Monsoon Season as Well. 

    We processed our data from the previous day and noticed that the high band antenna had considerable radio frequency interference (RFI), but that the low band was much quieter. To view the antenna response, we plot the antenna temperature (basically power) vs frequency. An ideal plot would be a smooth curve, but when RFI is present, there will be occasional narrow RFI spikes at various frequencies.

    The frequency of FM radio is in the range of 88 to 108 MHz. Despite the lack of FM reception on our car’s radio, the low and high band antennas picked up a forest of spikes in the Radio Band. It appears one can not escape FM radio.

    Other than FM radio, the low band interference was not that bad. We decided to use day 4 to search the area for other locations which were good in the low band, by using our small biconical dipole antenna and measure for 10 minutes for a NS orientation and 10 minutes for an EW orientation.

    We traveled a 180 mile loop around the area, stopping in various (4) places. The loop took us 9 miles north of the ranch on Nevada Hwy 21 (Grass Valley Rd) and then 21 miles westbound on another road (name unknown) to Hwy 278. Going south on 278 for 41 miles brings you to Eureka, the first decent sized town in the area. The next part of the loop is 69 miles of Hwy 50 (westbound), which meets up with Hwy 21. 40 miles of the gravel road Hwy 21 brings us back to Gund Ranch.

    We tried 4 locations. The first location was on the road whose name we are uncertain of. We were able to get in a full measurement. The second location was a few miles south on Hwy 278 near the Alpha ranch. Our measurement there was cut short by about 5 minutes due to a rain cloud that popped up suddenly. Our third measurement was 30 miles into Hwy 50. That measurement was called off due to rain before we could even set up. The fourth measurement was also off of Hwy 50, but about 5 miles north of there on a side road.

    We did get in some measurements on day 4 despite the rain. However, lightening did add spurious RFI to our data, and the data might not appear as clean as it should actually be.

    At the end of the day, the Ranch Manager, John, paid us a visit and confirmed an earlier invitation to us to have dinner with him and his wife at his house the next day (steak from his cattle), but there would be additional guests because his wife had reminded him that it was his birthday tomorrow!

  • tmozdzen 11:33 pm on July 17, 2014 Permalink | Reply
    Tags: , astronomy, , , ,   

    Nevada Field Trip Days 1, 2, and 3 – The Search for a Quiet Location to Listen for the EOR Signal 

    The EDGES program under Professor Judd Bowman is searching for a site which would be nearly as remote and quiet (in the radio frequency ranges of 50-200 MHz) as the current site in Western Australia, but slightly more convenient to get to for testing and development.  The Global Epoch of Reionization (EOR) signal is very faint and must be carefully extracted from a bright sky almost 100,000 times greater in magnitude, so the fewer stray signals we pick up, the better our chances of successfully extracting the signal.

    It was for this reason that Raul Monsalve (post-doc) and I (PhD candidate) packed a nice new SUV rental with our antenna gear last Monday and headed off to the middle of Nevada. It’s a long trip, so we were forced to spend the first night in Las Vegas. And on the second day, via the extraterrestrial highway (318), we arrived at the Gund Research Ranch operated by the University of Nevada Reno. (http://www.ag.unr.edu/about/facilities/gund_ranch.aspx). During the drive on the second day, we were encouraged by the weakness (and most of the time the lack of reception) of FM radio stations.

    The ranch manager had a nice empty cabin available and was very hospitable. He showed us the boundaries of the ranch (100,000 acres when considering public and private lands) and told us of the hot springs in the area. One undesirable by-product of the hot springs is that the longer you let the cold water run, the hotter it gets, to the point of scalding. The ranch research focuses mainly on cattle, but people come to the ranch to conduct research on a variety of topics. He also pointed out several spots in the field that might interest us which didn’t have cattle roaming around that we might want to visit the next day.

    On the third day, we took the packed SUV out onto a field on the ranch property. The rancher warned us to get out of there asap if it started to rain, because the road would get slick as butter and we’d have no chance of exiting. The road consisted of two tire tracks without vegetation amid a field that was a forest of thriving desert scrub brush plants. After going into the field for about a mile, and fearing we might not come back out if we drove much further, we found a place to set up our antenna and take measurements.

    We brought 3 antennas with us and took measurements with all of them at this site:
    1) A low band antenna sensitive in the range of 50 to 125 MHz
    2) A high band antenna sensitive in the range of 80 to 200 MHz.
    3) A small biconical dipole antenna sensitive in the range of 50 MHz and above.

    After 2 hrs, we set up the low band antenna and took 2 hrs of measurements. We then switched antennas and took 2 hrs of measurements with the high band antenna. Because at 2 pm a few drops began to fall during the high band measurements, we decided to make the bi-conical dipole measurements in parallel to hasten our departure (we could do this because the dipole used a different piece of equipment than the low and high band antennas). If it really started to rain, there was no way we could shut down and get out of there in under 40 minutes, so we foolishly took our chances and completed all of our measurements. Luckily the few drops of rain stopped and we made an uneventful return to the ranch.

    We are now looking at the data we recorded and will update you on the results in the next blog entry.

  • mpbusch 8:47 pm on April 13, 2014 Permalink | Reply
    Tags: astronomy, istb4, ,   

    LoCo Outreach 

    Hello LoCo followers! My name is Michael Busch; I am currently a sophomore at Arizona State University majoring in Astrophysics and Computational Mathematical Sciences. I started working in the Low-Frequency Cosmology (LoCo) Lab in August of 2013 under both Dr. Judd Bowman and (more directly) Dr. Danny Jacobs. The LoCo lab is involved with some awesome radio research, as Nithya described last post. This semester, I am helping Danny identify sources of noise in the power spectrum of the Murchison Widefield Array (MWA). One of my other regular duties in the lab is aiding in the lab’s education and public outreach department. LoCo participates at a majority of the events hosted by the School of Earth and Space Exploration, including Earth and Space Open Houses and other special events, such as Earth and Space Day and Night of the Open Door.

    Night of the Open Door occurred in March, this is the biggest public education and outreach event that Arizona State hosts. All of the colleges and schools in the University host their own events and open their doors to the public for them to see some of the cool research that lab groups and departments are conducting. Planning for this event had been ongoing for many months, and many different groups in the School of Earth and Space Exploration (SESE) participated.

    As with many events well-planned and organized—catastrophic weather struck and monsoons doused the ASU Tempe campus.

    This was, overall, quite unlucky for the outdoor demonstrations across campus, but dramatically increased the influx of visitors to our building. LoCo had two tables full of demos and information for the public: including one of the dipole antennas used in the MWA, the Octocopter autonomous flying drone, Radio Frequency Interference (RFI) detectives, a giant word search puzzle, and a poster that I made explaining some of the general science behind the MWA. Despite the weather, Night of the Open Door yielded an amazing turnout, and the LoCo table was quite the hit!

    The LoCo lab at Night of the Open Door, with the Octocopter on display. From left to right, Michael, Danny, Tom, Jackie, and Nithya.

  • tnithyanandan 7:08 pm on March 21, 2014 Permalink | Reply
    Tags: astronomy, Cosmology, , , low frequency, , power spectra, , , ,   

    Joining ASU and a peek into my research 

    My name is Nithyanandan Thyagarajan. I joined the LoCo (Low frequency Cosmology) lab group at ASU SESE headed by Prof. Judd Bowman, in September 2013 as a postdoctoral research scholar. I did my bachelor’s in Electrical Engineering from IIT Madras, India. For my PhD thesis at Columbia University, I worked on identifying and characterizing variable and transient radio objects by conducting one of the biggest searches of its kind in the radio sky. I then moved to Raman Research Institute in Bangalore, India as a postdoc and worked on statistical characterization of foreground contamination in the power spectrum of redshifted 21 cm line emission of neutral hydrogen during the epoch of reionization (EoR). During this period I got associated with the Murchison Widefield Array (MWA) project.

    The LoCo group has members involved in a variety of interesting projects. Besides having a strong presence in the MWA project, the members are also involved in other EoR experiments using the Experiment to Detect the Global EoR Step (EDGES), Precision Array for Probing the Epoch of Reionization (PAPER), Dark Ages Radio Explorer (DARE), Long Wavelength Array (LWA) and other theoretical and modeling projects. I am excited to be a part of this diverse group which provides enormous opportunities to learn science through the many perspectives from these different experiments.

    Currently, I am focusing on setting up simulations to predict the response of the MWA telescopes to all-sky radio emission. My aim is to isolate and characterize the signatures of different spatial structures of foreground objects such as the Milky Way, and other extragalactic objects besides the instrument’s own systematic effects on the observed power spectrum that contains information about the spatial distribution of redshifted 21 cm line emission from neutral hydrogen from the EoR. An understanding of the radio foreground objects and that of the telescope is extremely significant because the expected signatures from the neutral hydrogen emission during the EoR are extremely faint compared to the contamination from radio foregrounds and instrumental artifacts. Detecting EoR signal may be impossible without a precise removal of such contamination and artifacts.

    Here’s an approximate simulation of the radio foreground and instrumental signatures we expect to see in the power spectrum when the entire hemisphere of the sky is observed by the MWA telescope. The simulations are found to match well with results from analysis of data from the MWA telescopes.

    Predicted spatial power spectra of a an all-sky model as seen by MWA telescopes.

    Predicted spatial power spectra of an all-sky radio model of foreground objects as seen by MWA telescopes. The all-sky radio emission model is shown in the central panel. The peripheral panels show the power spectra recorded by different antenna pairs (x-axis) grouped by orientation of the lines joining them (EW at bottom right, NE at top right, NS at top center, and NW at top left). The x-axes in all the peripheral panels represent the different antenna pairs which sample the transverse spatial information from emission from the plane of the sky while the y-axes sample spatial structures into the plane of the sky. Since the sky model contains heterogeneous spatial structures, these different antenna pairs record different spatial information. The wedge/fork shaped feature prominent in the top center panel and the bright horizontal feature in all the peripheral panels arise out of the emission from our galaxy and other extragalactic radio emission (all the bright features enclosed by the forked black lines). The periodically repeated horizontal structures are caused by the frequency characteristics of the MWA telescopes.

  • margaretelizabethblumm 10:18 am on August 9, 2013 Permalink | Reply
    Tags: astronomy, conference, education, , ,   

    Astronomical Society of the Pacific Meeting 

    Recently, I attended the Astronomical Society of the Pacific’s annual Education and Public Outreach conference in San Jose, CA to represent the Low-Frequency Cosmology Group (LoCo Lab).  It was an amazing experience!  I met with many people involved in the educational outreach community from across the nation.

    I presented a postertitled “RFI Detectives: Raising Awareness of the Radio Sky” describing an activity we modified to use for large public events.  This activity helps us to teach aboutradio wavelengths, frequency, and radio astronomy using hand-held radios to let children search for sources of radio frequency interference; or RFI, for themselves.  We adapted the activity from the NRAO activity “Be an RFI Detective”.  Many people came by to view and discuss my poster, and seemed quite interested in the research we are doing.

    I attended numerous talks about a variety of things, from the politics of astronomy education to how to teach astronomy to preschoolers.  Everyone was so knowledgeable and incredibly kind.  I networked and make contacts that will assist in future efforts toward a career in education outreach.

    One of the sessions I went to was about how to teach the scale of the Universe.  I was amazed to see how far apart the planets are.  We had string that was scaled to the distance of the planets (I don’t remember what the scale factor was), and we stretched out the Solar System.  I objectively knew that the distances were huge, but seeing how the outer planets wouldn’t even fit in the room was surprising.

    The conference provided an invaluable learning experience and was fascinating. I am very grateful that I was able to go and meet so many like-minded people who share my passion for teaching the world about the wonders of space. This was a wonderful opportunity and I will make sure to use all I have learned to improve the outreach here and get people more interested in space.


  • kdavis32 2:27 pm on May 15, 2013 Permalink | Reply
    Tags: astronomy, , ,   

    Characterizing EDGES Radio Frequency Interference 

    Hello LoCo followers! As the avid readers should know, the LoCo team is working on developing a ultra-sensitive radio telescope, EDGES, in order to detect faint emission signals from the very earliest stars and black holes that formed in the universe. Since the signals are so faint, EDGES must be the most sensitive instrument of its kind. However, the high response of the telescope to small signals can be disadvantageous, since there are many other radio sources that can “drown out” the desired signal. Most everyone has experienced this effect as static on a car radio. In this case, the EDGES frequency range actually includes the FM band, and the radio signals that you want to hear in your car is, to us, just like ‘static’ that interrupts your favorite broadcasts! In fact, astronomers call this unwanted interference ‘noise’ even though it is caused by electromagnetic waves instead of sound waves.
    Here at ASU, I am looking at the radio frequency interference (RFI) patterns that disturb our observations of the early universe. In figure 1, you can see a typical plot of the intensity at a given frequency during the course of the day. The X-axis is a plot of frequency, and the Y axis shows time at one minute intervals. A red pixel shows that there was a lot of incoming flux at a given frequency, and blue shows a low level of flux. The large red sphere is actually the radio emission of our Milky Way galaxy. The vertical bands of high flux correspond to radio frequency channels that we humans use for broadcasting. Some of these bands are used for FM radio, some are used for GPS, and others are used for industrial or amateur radio communication (like cell phones or satellite TVs).

    Antenna Temp 2011_315_00_Ta

    The intensity of the RFI signals in these bands changes throughout the day for a wide variety of reasons. I am looking for times when the power is unusually high, and seeing if those events correlate to known environmental phenomenon. For instance, one of Earth’s atmospheric layers is composed of high temperature particles that have been stripped of their electrons and form ions, thus the layer’s name ‘ionosphere’. When a force perturbs this layer, the charges move around in wavelike patterns. Moving electrical charges radiate photons, and the frequency of the radiation is dependent on the frequency that the ions oscillate. If the ions oscillate at radio frequencies, then there will be an increase in radio photons coming from the ionosphere, and the EDGES instrument will record that event. Other RFI sources that cause noise in the data are meteor showers (that perturb the ionosphere), ionospheric clouds, solar flares, and geomagnetic storms.
    The frequency at which radio waves can propagate through the ionosphere is called the critical frequency. Signals at higher frequencies than this escape to space, while signals at lower frequencies
    are reflected back towards Earth. Figure 2 shows a plot of the average critical frequency of the f1 layer of the ionosphere for each day from 2007 to present, which spans the time period that the EDGES instrument has been running. You can see that there are seasonal peaks each year, due to the orientation of the earth’s magnetic field compared to the direction of the sun. I am interested in finding the spikes in the data, to see if there are any peaks in the RFI intensity on those dates.

    RFI 2011_315_00_rfi

    As mentioned above, infalling meteors are known to cause perturbations in the ionosphere. Many of these meteor showers are spectacular to view with the naked eye, but a few are so faint that we only know they are there because of the disturbances they make in the ionosphere that have been recorded by other radio instruments. Figure 3 shows a plot of how many meteors are expected to hit the atmosphere for any given day. They are separated into ‘visible’ and ‘radio’ showers, based on whether they are visible to the naked eye or have been detected by radio instruments only. The X axis runs over one year only, since the Earth only runs into each group of meteors once per year due to our orbit around the sun. The Y axis gives the Zenith Hour Mean (ZHM), which is the total number of events predicted to occur during the hour that the shower has the most meteors.

    Total Expected Radio and Visible

    So far, I have been working on getting the data into a format that will be meaningful to do the comparison between. In the next few weeks I should start to see if there are any of the correlations between the ‘noise’ in the EDGES data and the events that happen in the sky above it. If this is successful, I can use the information to remove the events from the data so the astronomical signal we want to detect will be clearer. Wish me luck!

  • dannyjacobs 3:08 pm on April 10, 2013 Permalink | Reply
    Tags: astronomy, , ,   

    In the name of science 

    Science experiments, as in life, are plagued by uncertainties.  As sarah showed last week, a particularly pernicious one is the response of the  telescope across the image. Things tend to get dimmer towards the edges, but without some very well known source in that area, its difficult to correct.  Most telescopes get around this problem by physically scanning across a known source, tracing out the response function.  Our new low frequency telescopes (MWA,PAPER) are fixed to the ground, we do not have the option of moving the telescope. So its time to get creative.  We can use satellites, known astronomical radio sources, or we can even fly a known transmitter over the telescope.

    So, I hope this explains this picture here.


    Danny flying the Octocopter. Next, we’ll be attaching a calibration antenna.

    The Octocopter is on loan from our colleagues at Curtin University. (Here’s a great video they made with it.) We’ll be attaching a calibration source and flying grid pattern over the telescope.  Today we just attached a go pro camera.  Here’s the footage

  • seasterb 2:23 pm on March 25, 2013 Permalink | Reply
    Tags: astronomy, , ,   

    Is it Abstract Art or Science? 

    Many cosmological questions about the early universe are on the horizon of scientific discovery at this time. Theorists have come up with a time line that shows the development from the Big Bang to the present gigantic and complex universe. Can we prove what the theorists have predicted? Perhaps – but with every measurement there is some amount of error and uncertainty. Unfortunately, the uncertainty that can be tolerated in our group’s experiments to be able to state definitively, “We know when the first stars and black holes formed” is ridiculously small. The project that I have been working on for the last year set out to find the error related with using an antenna at varying locations on the Earth and different times during the day to make accurate measurement of the radio spectrum. Every antenna has a beam pattern – which is the area that an antenna can collect information from, and each beam pattern has places that are more sensitive and less sensitive to incoming signals.
    By projecting these beam patterns onto a temperature coded map of the sky, an estimate of what that antenna can “see” at that time, frequency, and location on the globe can be made – but if you ask me, most of the information I get resembles a painting I would love to hang on my wall.

    Figure 1- Sky Map at 408 MHz

    Figure 1- Sky Map at 408 MHz

    Figure 2-Beam in Azimuth and Elevation

    Figure 2-Beam in Azimuth and Elevation

    Figure 3 - Beam in Right Ascension and Declination

    Figure 3 – Beam in Right Ascension and Declination

    Figure 4 - Beam Projected on the Sky Map

    Figure 4 – Beam Projected on the Sky Map

    Figure 1 shows the temperature coded map of radio emission from our own Milky Galaxy in the sky – red is hot and blue is cold. Figures 2 and 3 above show how the modeled beam pattern looks for a physical antenna in two different astronomical coordinate systems. Figure 4 filters the beam pattern, modeled on the data set generated for the antenna beam pattern filtered by RA/DEC, against the sky map. On the color scale, red is the strongest signal and blue is the weakest signal. So as the earth rotates, the sky over the antenna will change and the red, or strongest collecting point, will hit different parts of the sky. In Figure 4, the beam pattern was projected on the galactic sky map at an arbitrary latitude, longitude, and time on earth (in this case a location in Australia).

    After this projection, the temperature of the projected map was summed at each frequency. Once this was coded, I add a series of “for” loops in my software to change the antenna’s latitude from -90˚ to 90˚, the time from hour 0 to 24, and the orientation azimuth from phi of 0˚ to 360˚. After plotting as a function of frequency, the curves were fitted with a second order power curve with the form: Ax^B+C. All of the curves and the corresponding residuals were plotted on the same figure for better comparison (Figure 5 and Figure 6 below). Once on the same plot, the curves that had an error larger than 0.05 K were eliminated. The last step was changing the time and the location simultaneously to determine the best combination of data collection of those two parameters – this can be seen in Figure 7. So far, our experiment site in Western Australia at -27 latitude is looking pretty good (at least for part each day)!

    Figure 5 - Temperature Sum For Different Latitudes

    Figure 5 – Temperature Sum For Different Latitudes

    Figure 6 - Residuals for Best Latitudes

    Figure 6 – Residuals for Best Latitudes

    Figure 7 - Best Latitude and Time to Collect Data

    Figure 7 – Best Latitude and Time to Collect Data

    This process, although easy to write out step by step, was quite particular. Taking hundreds upon hundreds of data points from an antenna and figuring out how to adapt the program that was written for the theoretical case was less than straight forward.

    So, is it abstract art or science??

    Plot of the Coordinates - This one is fun to look at!

    Plot of the Coordinates – This one is fun to look at!

    Another plot of the coordinate system that is just fun to look at!

    Another plot of the coordinate system that is just fun to look at!

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc