Education

NRAO TWELFTH SYNTHESIS IMAGING WORKSHOP, 2010

Posted on February 27, 2010 By Web Master

Impressions by Jamie Riggs

The first announcement of the National Radio Astronomy Observatory (NRAO) Twelfth Synthesis Imaging Workshop for 2010(http://www.aoc.nrao.edu/events/synthesis/2010/) appeared on the NRAO website in February, 2010. I promptly signed up as in years past there was a waiting list (the workshop is limited to 150 participants). The Twelfth Synthesis Imaging Workshop took place June 8-15 in Socorro, NM. The school was an eight-day-week of lectures on aperture synthesis theory and techniques at the astrophysics graduate student level. There were basic lectures on synthesis imaging, and advanced lectures on more specialized techniques. Two of the days were practical tutorials in Astronomical Image Processing System (AIPS) and the newer Common Astronomy Software Applications (CASA) package demonstrating data collection, calibration, and imaging of both Expanded Very Large Array (EVLA), Very Long Baseline Array (VLBA), Combined Array for Research in Millimeter-wave Astronomy (CARMA), and Atacama Large Millimeter Array (ALMA). It was a full and enriching week.

The workshop participants came from all over the world. They were students, engineers, technicians, and, of course, astronomers and astrophysicists. The world’s great radio observatories were represented in the participant list. ALMA sent a large contingency as it had first science with five dishes just weeks before the workshop. Science proposals will be accepted beginning in November, 2010. Much excitement prevailed at the workshop as a result.

The first day, Tuesday, was registration followed by five, one hour lectures. That evening, NRAO gave us a very nice reception. Wednesday was a full day of lectures. I should mention that each day of lectures ended with discussion sessions headed by the presenters. This gave us ample opportunity to ask questions with answers much more detailed than was practical following the lecture itself. Thursday was another full day lectures, and the ALMA group held an informative reception after. They went over many of the aspects of the Chilean facility necessary for the scientists to begin forming research questions. (Seehttp://science.nrao.edu/alma/index.shtml for more information.)

250 LWA dipole pairs.

Friday was the first day of data reduction tutorials. We had our choice of using AIPS ( http://www.aips.nrao.edu/ ) or CASA ( http://casa.nrao.edu/ ). I was advised to sit for the CASA tutorials as it is newer and likely to be the future of synthesis imaging packages. The tutorials were online, but each section of students had three NRAO scientists, post doctoral professionals, or PhD students to assist. I learned quite a bit about just how radio astronomers analyze interferometry data. The day was in two halves, separated by lunch and a tour of the NRAO Science Operations Center (SOC) on the New Mexico Technical University (NMT) campus. The tour included the correlator room, the fiberglass communications systems between the SOC and the VLA antenna site (http://www.nrao.edu/index.php/about/ facilities/vlaevla) an hour to the west. We learned how the data drives used in the correlators were shipped to and from the VLBA sites, located from Hawaii to St. Croix, with the EVLA as the VLBA center ( http://www.nrao.edu/index.php/about/facilities/vlba ). The tour ended with visits to the feed horn engineering labs used both on the EVLA and ALMA dishes, as well as the ALMA receiving system development laboratory. The only description I can think of is: Amazing!

Saturday was hike and pool party day. We hiked up South Baldy Ridge in the Magdalena Mountains to the Magdalena Ridge Observatory ( http://www.mro.nmt.edu/Home/index.htm ). The Magdalena Ridge Observatory (MRO) is primarily intended for astronomical optical interferometry research and will be composed of two facilities, a single 2.4-Meter telescope and an array of optical/infrared telescope interferometers. It is located on South Baldy Ridge, about 30 miles west of the NMT campus. At an elevation of 10,600 feet above sea level, it is the fourth highest observatory in the world. Upon returning from the observatory, we all cooled off in the New Mexico Tech Swim Center. Food was plentiful! This was followed by a party hosted by a NRAO post doc. Margaritas galore!

One of the dishes!

Sunday was perhaps the most exciting day for me. We all traveled out to the VLA antenna site west of the town of Magdalena. It was an impressive view as we crested the range encircling the antenna location. The antennas were in the compact array, offering excellent photographic vistas. Our tour began in the operations center, which has a signed photograph of Jody Foster in the control room (as does Arecibo). We saw how the antennas were controlled for EVLA and VBLA observing, and how the data were brought to the communications room for transmission to the SOC in Socorro for correlation. Next, we visited the Long Wavelength Array dipole antenna farm just south of the EVLA antennas. The LWA is an effort to advance astronomy by using inexpensive antenna stations to build a very large aperture to probe at the lowest frequencies between 10 MHz and 88 MHz.

Our next stop was the maintenance hanger for the EVLA dishes. A railroad system is used to deliver the dishes to the hanger, and to position the dishes in the various observing locations. The hanger reminded me of a smaller version of the shuttle hanger at Cape Canaveral. One of the dishes was in the hanger, and it looked much taller in there than out on the open desert!

Tour of a dish.
Finally, we were allowed to crawl all over one of the dishes at its observing location. The pedestals have three levels. The first contains the communications consoles, and the second contains the receiver consoles. The third level contains the various feed horns. Up a ladder, through a hatch, and we were walking on the dish surface. The secondary reflector held a low frequency, polarized dipole. The feed horns were numerous. They were mounted on a turntable to allow for easy selection. It was spectacular!
The VLA

Monday was the final day of lectures, followed by the farewell dinner hosted by NRAO. Many of us then adjourned to the Capital Bar (the Cap), as was the case most nights. It is just about the only place in town for after-hours entertainment. A very good time was had by all.

Tuesday was the last day of the workshop, and the second day of data analysis tutorials. I worked with CARMA 3C123 spectral line data. I gained much insight into how astronomers work their interferometer spectral data.

Lunch that day was provided by the NRAO organizers. I sat with one of the NRAO associate scientists. He and I carried on an animated discussion of statistics in radio astronomy data analysis. He suggested I think about working on the very illusive Radio Frequency Interference (RFI) contaminators buried in the source signals. “We certainly can handle the strong, easily identified sources,” he said, “but the weaker RFI, convolved with the source signal itself, we continually scratch our heads over.” Needless to say, I am now searching out and studying the exiting RFI literature…

The amount of information presented during the workshop was enormous. Many of us will be studying the material for quite some time. Although we all worked very hard, we also had plenty of fun. We made new friends, and reacquainted ourselves with past friends. I reconnected with several of my NRAO Arecibo Single Dish School classmates, and we enjoyed a delicious reunion dinner at the Socorro Springs Brewing Company. I heartily recommend the imaging workshop. So much so, that I’ve signed up for the first one to be held in Chile!

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DSES COLLABORATION WITH FRONT RANGE COMMUNITY COLLEGE

Posted on December 4, 2009 By Web Master

Jamie Riggs, December 4, 2009

DSES and the Front Range Community College (FRCC) Boulder Campus have had an informal association for many years. Dr. John Minors, Science Department Chair of the Boulder campus has been, and is, a DSES member.

  Paul making final adjustments.

In addition, he has brought small groups of students to T22 as part of his FRCC astronomy class segments in radio astronomy. When the groups became too large for T22 to accommodate, John purchased a Small Radio Telescope (SRT) system, developed by the Massachusetts Institute of Technology (MIT) Haystack Observatory 
(http://www.haystack.mit.edu/edu/undergrad/srt/index.html), and available in kit form through CASSI Corporation (http://www.cassicorp.com/), for his students to use on the FRCC campus.

 

Dr. Minors assembled and mounted the telescope at the Longmont campus laboratory and classroom building. Due to time constraints, however, he contacted

  John describing dish fundamentals to
FRCC students.

DSES for help in completing the installation and calibration of the SRT. Rodney Howe volunteered to assist, but, as Paul Berge and Jamie Riggs had easier access to the Longmont campus, Rodney graciously gave the project to Paul and Jamie.

 

John provided the necessary maintenance cables, and Paul and Jamie, with cables and tools in hand, ascended to the roof. Paul repaired, adjusted, and lubricated the mechanical systems, and tied off the cables. Paul and Jamie then exercised the dish to characterize its behavior. As it turned out, all this activity was visible to a faculty meeting across the courtyard. Apparently, it was the highlight of the meeting!

The team of John, Paul, and Jamie continued refining the SRT operation by establishing the tracking correction offsets in the

  Jamie working with FRCC students on a laboratory
exercise about the Sun.


SRT computer controller software. Initial tracking accuracy was verified using the Sun’s shadow projected onto the center of the dish. This was followed up by assuring the maximum signal strength was maintained while tracking such sources as Sag A and Cyg A. This work was accomplished after the team moved back into the laboratory radio telescope control/receive station, which was part of the SRT kit. John set up the station for optimum viewing and use by the students.

 

John and Jamie then tried a variety of teaching scenarios to fit the time and information constraints imposed by the astronomy curriculum. The result was a laboratory procedure for Solar observations, (see SolarLab.pdf). This lab is loosely derived from the SRT laboratory exercises of Whitlock and Pulliam (2008). The purpose of the lab is to learn the basics of operating the SRT, and create temperature versus frequency, centered at 1,420 MHz, plots of the Sun in the SRT software, and using the R statistical analysis package (R Foundation, 2009, http://www.r-project.org/). The procedure has seven components:

  1. Power-up and initialize the SRT system.
  2. Calibrate the telescope.
  3. Point, track, and record solar data.
  4. Park the dish.
  5. Open the R statistical analysis package.
  6. Analyze and the recorded solar data.
  7. Interpret the plots.

This is just a beginning. John has plans for additional laboratory exercises using the SRT. As DSES facilities mature, it is hoped that further student activities using the 18-meter dishes will be possible. Overall, however, we had an enjoyable and rewarding collaboration.

Whitlock, L. A. and Pulliam, K., 2008, Listen Up! Laboratory Exercises for Introductory Radio Astronomy with a Small Radio Telescope, New York: iUniverse, Inc.

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CU AEROSPACE STUDENT DESIGN PROJECT TO DEVELOP CONTROL SYSTEM FOR THE TABLE MOUNTAIN ANTENNAS

Posted on October 24, 2009 By Web Master

Table Mountain Field Site, Longmont, Colorado – Oct 24, 2009

 

A CU senior design project group called COSMOS in the CU Aerospace Department is working to develop a new feedback control system for the high gain dish antennas on Table Mountain.

The members of COSMOS are senior aerospace engineering students working under the direction of CU Aerospace Professor Dennis M. Akos on their Senior Software Design Project in order to fulfill their coursework requirements for their undergraduate program.

The COSMOS Team is pictured here at the Table Mountain Antenna site. Shown from left to right are Michael Reher, Vu Nguyen, Samantha Krening, Ian Aber, Miranda Rohlfing, James Binney, Miles Buckman with the Table Mountain Lower Antenna.

The COSMOS Project website was established by the students to document and track the project progress.

The primary goal of the COSMOS project is to design, fabricate, and implement a feedback control system for a high gain antenna capable of tracking celestial objects and satellites in Earth orbit. This effort requires an antenna pattern characterization, orbital and celestial determination software, and mechanical analysis. Once it is completed it is hoped the new system will enable professors, groups such as DSES, ITS, the Air Force, and others to use the dish for their own studies.

For further information see the DSES/CU Liaison at DSES.

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RADIO ASTRONOMY SUMMER SCHOOL

Posted on July 12, 2009 By Web Master

Arecibo, July 12, 2009

A unique program in single-dish radio astronomy was held during the week of July 12, 2009 at the Arecibo Observatory in Arecibo, Puerto Rico. This was the fifth time this program was offered and it was

Arecibo Observatory, a 305m (1000 ft) fixed spherical dish with Gregorian secondary reflectors.


attended by over fifty students including DSES member Jamie Riggs. The objective of the school is to provide graduate students, post-docs, and experts in other fields of astronomy with both knowledge and practical experience in the techniques and applications of single-dish radio astronomy. Over 20 mentors were provided to help the participants with their research.

 

The program was sponsored by the National Astronomy and Ionosphere Center (NAIC) that operates the Arecibo Observatory, and the National Radio Astronomy Observatory (NRAO) of Green Bank, West Virginia.

The program was based around an intensive series of lectures from experts. A significant part of each participant’s time at the school was spent performing a hands-on radio-astronomy project. For this, they had to make observations with either the Arecibo 305-m telescope or the Green Bank 100-m (GBT) telescope, analyze the data acquired, and interpret the results.

The project in which Jamie parrticipated was directed by B. Murray Lewis and coauthored with Kim Arvidsson and Matthew Povich. An abstract and related slides can be found here and a writeup of her experience with the program can be found here.

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