Summary of 2011 SARA Western Conference, 2 – 3 April

By: Julian Jove

The SARA 2011 Western Conference was held at the Embry-Riddle Aeronautical University in Prescott, Arizona. Ray Fobes, Staff Radio Astronomer and SARA member, was our host. He provided a nice lecture hall for our meetings and Bill and Melinda Lord, SARA president and treasurer, respectively, kept us organized and, for the most part, out of trouble. Well, at least the group was not mentioned in the Prescott Police Blotter.

ERAU (right, source: ERAU) has a heavy emphasis on space physics and aviation. Prescott is about 1 mile (1.6 km to the rest of us) above sea level with interesting rock formations, Wyle Coyote and the Road Runner, excellent weather, plenty of brush and desert, and like much of Arizona it has dark skies.

There were about 20 attendees including several ERAU physics students. If you did not attend, you missed some interesting talks and discussions, which are described following:

On the first day of conference presentations, Saturday, we had opening remarks and announcements by SARA president Bill Lord and host Ray Fobes. We then heard from John DuBois, who described the limitations of diode detectors used in radio astronomy applications followed by a description of a modern True Power Monitor based on the Analog Devices AD8362 integrated circuit. Diode detectors generally are suitable for small signal levels over a limited range of about -40 or -50 dBm to -35 dBm, whereas the AD8362 provides an effective range of about 0 to -50 dBm. John used the AD8362 in his 1420 MHz radio telescope and showed results of a drift scan of the Rosette Nebula (CTB21) and the Moon using a 4 m dish. His presentation was followed by some discussion of dish antenna pointing and tracking and the difficulties of making noise temperature measurements.

Whitham Reeve presented a tutorial on geomagnetism, the study of the Earth’s magnetic environment. This presentation was an updated version of a presentation he made at the 2010 SARA Annual Conference. He covered the sources and causes of the field and its characteristics as well as how it is affected by solar activity such as coronal mass ejections (CME) associated with some flares, magnetic reconnection and coronal hole high-speed streams.

Rodney Howe then talked about Solar Cycle 24 and the speculation that it may be unusually quiet. He used American Association of Variable Star Observers (AAVSO) Sudden Ionospheric Disturbance (SID) data and compared it to Geostationary Operational Environmental Satellites (GOES) data. The present forecasts are for relatively low daily sunspot numbers at the peak, which is expected to occur in 2013. One of the problems in using the older SID data produced by AAVSO is that it was based on an Importance Rating whereas modern data uses the classification system A, B, C, M and X to indicate solar flare magnitudes. Converting one to the other is laborious and difficult. Because of the readily available data from GOES, AAVSO has considered abandoning their SID program. The question arises, is it worth retaining the data produced by AAVSO since 1964? Rodney proposed that SARA provide stewardship of the data if AAVSO does, in fact, abandon the program. He also proposed that 2.8 GHz receivers be built to provide terrestrial data at the same operating frequency as the GOES solar monitor.

Next, Andri Gretarsson, assistant professor of physics at ERAU, made a presentation on Gravity Wave Detection. He discussed sources of gravity waves and methods of detection. Of particular interest was LIGO, Light Interferometer Gravitational Wave Observatory, which is being used for detection at a capital cost of about US$300 million and annual cost of US$30 million. “Initial LIGO” has been built and Advanced LIGO is under construction. He demonstrated “Table-top LIGO”, a setup somewhat similar to but a little more complicated than Albert Michelson’s original speed-of-light experiments.

Next, Judd Bowman, assistant professor at Arizona State University, described 21 cm wavelength (1420 MHz) cosmology in his presentation “Epoch of Ionization”. The EoR is based on the concept of the Big Bang and refers to the process during which the inter-galactic medium was ionized by the emergence of the first stars, galaxies and quasars. Measurements of this phenomenon are notoriously difficult. Of particular interest are the two radio telescopes MWA (Murchison Widefield Array) and EDGES (Experiment to Detect the Global EoR Signature). EDGES is designed to enable precision measurements of the smoothness of the all-sky radio spectrum between 45 and 200 MHz and to demonstrate the limits of the redshifted 21 cm HI emission contribution to this spectrum. Similarly, through measurements of the power spectrum in the 80 – 300 MHz range, the MWA is used to study fluctuations in the redshift of the 21 cm emission. The MWA is installed in very remote areas to reduce the problem of radio frequency interference. Judd showed us many photographs of his travels to Australia and elsewhere to install the WMA radio telescopes.

We then heard from several ERAU freshman students. David Stiles and Kelsey O’Connor described their radio and optical astronomy outreach program. They use an Itty-Bitty Telescope (IBT) and optical telescopes to show differences between radio and optical astronomy. Amanda Gaska described their SID program, which they operate in conjunction with Stanford University. They use the SuperSID receivers, which is familiar to SARA members, and a loop antenna of their own design and construction. The loop is square and has 6 sq. ft area and 400 ft of wire with spaced turns. Victor Rice and Lorenzo Galicia described their 7 – 40 MHz spectrometer similar in concept to the Long Wavelength Array (the Erikson dipole or “Bat Wing Antenna”) and the RFSpace SDR-IQ software defined radio. They use three antennas with about 1 km separation in the Prescott area. Ray Fobes provided the final regular presentation for the day. He described the radio astronomy laboratory facilities at ERAU that cover various observation frequencies from VLF to UHF.

During the first evening of our conference we had a round table discussion on the Geometry of Large Rotating Systems by Cameron Rout with assistance by Bruce Rout. The presentation was a detailed follow-up of presentations on determining galaxy size and distance using general relativity at the 2010 Western Conference at Stanford University and the 2010 Annual Conference at Green Bank West Virginia and provided step-by-step discussion of the arithmetic and galaxy image analysis. The challenges I made after the 2010 conferences – to prove these analyses wrong – have gone unanswered.

The next morning, Whitham Reeve made the second of his two presentations on geomagnetism, this one on building and using the 3-axis SAM-III geomagnetometer. He described the results of his observations between October 2010 and February 2011, including magnetograms of geomagnetic sudden impulses and geomagnetic storms and disturbances caused by the Sun’s CMEs and coronal hole high-speed streams.

We then had an open forum on radio astronomy projects. Ray Fobes described the ERAU high-altitude balloon projects. Bruce Rout suggested projects for solar eclipse monitoring and Ray suggested using the IBT. Tom Kloecker described some of his work using the IBT and the Hands-On Universe website and associated image processing software. Bruce Rout discussed early education needs and Whitham Reeve reviewed his e-CALLISTO solar spectrometer project. Bill and Melinda Lord provided an update of the SuperSID project, which SARA handles in partnership with Stanford University Solar Center. SARA submitted a project to NASA and it was well received. Stanford University has transferred the project to SARA but presently still provides funding.

After lunch on Sunday, Ray Fobes showed us through the ERAU Observatory, which is in a nice setting near the main campus. It includes several parabolic dish antennas and Ettus Research USRP (Universal Software Radio Peripheral) receivers with GNU Radio software, a Radio Jove receiver and dual dipole antenna, a SuperSID with VLF loop antenna (described above) and a well-organized rack of electronic equipment and control center (photos provided by the students and Ray Fobes).

The people were great, the presentations were great, and the facilities were great. It was well planned and organized thanks to the efforts of Bill and Melinda Lord. Until next time . . . keep your eyes open and ears peeled.