Summary of 2010 SARA Annual Conference, 4 – 7 July

By: Julian Jove

The SARA 2010 Annual Conference was held at the National Radio Astronomy Observatory (NRAO) at Green Bank West Virginia just about 1 gazillion miles from anywhere. If you do not believe me, haul out GoogleEarth and go to 38-25-51.11N : 79-48-58.63W geographic coordinates. This location is in what the Federal Communications Commission calls a National Radio Quiet Zone. It

is one of several NRAO facilities around the US and elsewhere. Leave your amateur radio transmitter and cellphone at home when you visit this place. It is a homeland security issue (the standard excuse for anything these days). Fellow observers: They have no sense of humor about radio interference. That aside, Green Bank is the home of the 100 m GBT (Green Bank Telescope, see photo) and several other radio telescopes in varying sizes and configurations. The location is scenic and beautiful and, except for the heat, a great place to practice radio astronomy.

For me the conference started early Sunday afternoon when then vice president Bill Lord offered to drive Dave Thomas and me around the NRAO grounds. Our tour guide drove the diesel powered paddy wagon around like it had no brakes, and it pounded us like it had no shock absorbers. It turned out the wagon neither, “so there” said Bill in his inimitable way. We shouted, Turn on the air conditioning Bill, it’s hot in here! His reply: “Open the dad-blamed windows!” (his words, not mine). The wagon has no air conditioning either.

My next stop was the 40 ft radio telescope familiarization workshop given by then president Tom Crowley at the classroom in the visitor center. I did not attend the radio astronomy beginner session presented earlier that day by Jon Wallace and David Fields. At Tom’s workshop we were given a quick tutorial on how to locate celestial objects using right ascension and declination. We then moved to the 40 ft radio telescope located about 3/4 mile to the northwest. The control room at this scope is located in an underground bunker (photo below, the entrance to the bunker is at bottom-left of photo, courtesy of Dave Thomas) and is filled with equipment that we were told dates from the 1960s. I did recognize some items from the 1970s. However, I did not see any HP 524A frequency counters with the decade counter nixie display, which I used in the 1960s.

The conference proceedings include a copy of the 40 ft scope Operator’s Manual. Goody two-shoes students who read the manual beforehand already knew what to do. The rest of us relied on Tom for expert on-the-fly guidance. It was obvious Tom had operated this scope before and knew that you do not follow the manual here and you have to do something different there. We were tasked with locating a particular radio source, adjusting the square law detector for optimum operating point, swinging the antenna to the correct azimuth and elevation and running the chart recorder. After using my bush-league setup at home, with which the chances of receiving anything of value are pretty small, I was excited to watch the source pass through the 40 ft radio telescope’s field of view according to plan and on schedule. I was impressed. The 40 ft radio telescope was open for our use during the rest of the conference and several members ran some interesting charts and did what I call ‘good radio astronomy’ (similar to, but better than, ‘good science’). I understand that none of the observers ran the scope off its rails or caused it to collapse from ‘metal fatigue’ as did the original 300 ft dish at NRAO in 1988 (no, I was not even in the area in 1988 so you cannot blame that on me).

We finished the 40 ft scope familiarization in time for a meal fit for a king at the NRAO cafeteria. It sounded like bedlam in the cafeteria because of all the SARA members in attendance, but there were no food fights that I participated in.

After dinner and after Tom Crowley had to yell really loud to get our attention, and which caused his wife to claim she did not know him and never saw him before, we had a very interesting presentation back at the visitor center by Dr. Rachel Rosen on pulsars. Pulsars are small but high mass neutron stars that spin so fast it makes your head spin thinking about them. When their emission mechanism is pointed at the Earth we receive their – you guessed it – pulses. Dr. Rosen described many types of pulsars leaving me with the thought that it would be fun to try to receive them at my observatory. Unfortunately, later in the conference, one of the presenters sobered me up by laying out the obstacles to receiving pulsars at high frequency (HF, decameter wavelengths) with anything less than 16,000 square meters worth of antennas. I will discuss this later. When the presentation ended, I knew the time change (jet lag) would get to me if I did not hit the sack to get a good night’s sleep before the presentations on Monday.

I missed the hands-on astronomy on the lawn session and the “my receiver is better than yours” and “your interferometer design is laughable” discussions in the Drake Lounge later that evening. If you attended these activities you would have had a chance to use a reconstruction of Karl Jansky’s antenna that played an important role in his discovery of galactic background radiation (above-right). Another on-site attraction was the original horn antenna used by H.I. Ewen and E.M. Purcell when they first observed the 21 cm inter-stellar hydrogen line in 1951 (left), but I could find no easy way to hook-up to it.

I believe around 60 people attended this year's conference. Vice president Bill and treasurer Melinda Lord did another wonderful job of organizing, setting up and keeping everything straight. They arranged for printing of the conference proceedings in a spiral bound format to make them easy to use. On the first day of conference presentations, Monday, we had opening remarks and announcements by Bill Lord and Tom Crowley, respectively. We quickly kicked them off stage so we could get to the keynote presentations by many of the Radio Jove Team including Dick Flagg, Wes Greenman, Chuck Higgins, Francisco Reyes, Jim Sky and Jim Thieman – all self-described “good-ole boys” according to a team photograph they showed. They gave a running presentation with the theme “Shoestring Radio Astronomy.” It emphasized the rich history of NASA’s Radio Jove project, its contribution to amateur radio astronomy and science education and recent improvements in the Radio Jove Receiver and Radio-SkyPipe software meant to improve data quality. Having the Radio Jove Team at the conference was a big treat for me because I had corresponded with most of the members for a couple of years and admired all of them but had never met any of them before the conference. They all were gracious and interesting to talk to and gave a first-class presentation.

We then heard from John Younger, a SARA member from Michigan, who gave a highly animated and energetic presentation describing his application of statistical methods to 20 MHz continuum measurements. He had spent quite a bit of time modeling his antenna beam geometry and then applying that to an estimate of the sky temperature at 20 MHz. He included the effects of strong radio sources such as Taurus A on continuum measurements. He discussed his observations from 12 evenings last winter, which, it turned out, were dominated by terrestrial radio interference. Not finding anything worthwhile in the data peaks he turned to what he called a “minimal measurement method”. This is based on the argument that all interference shown on a SkyPipe chart is in the positive direction, and that the galactic background could be found in the point-wise minimum of the chart trace. His final comments described a way to determine the number of observations required to estimate the galactic background noise temperature in the face of terrestrial interference. His calculations gave 10 observations as a rule of thumb. There were no accusations of hand-waving during John’s presentation, so we moved on to the next item of business, nominations of SARA officers and directors.

After nominations, Bruce Randall talked about his 2-element phase-switched interferometer operating at 408 MHz. He briefly discussed the arithmetic involved in phase switching and showed a block diagram of the receiver. Bruce then described his radio frequency (RF) phase switch that uses a double-balanced mixer and signal combiner. These are schematically quite simple as seen from his schematic in the conference proceedings. Of great significance were Bruce’s impressive reception results while using his design to detect a number of celestial radio sources.

Whitham Reeve presented a tutorial on geomagnetism, the study of the Earth’s magnetic field. 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) and coronal hole high-speed streams. When CMEs are directed at the Earth, they sometimes cause geomagnetic storms, and the magnetic fields associated with coronal holes high-speed streams can interact to the Earth’s magnetic field causing aurora and other phenomena (this is called magnetic reconnection).

We next heard about the INSPIRE project from Paul Schou and Ellen McLean. INSPIRE is a NASA project similar to the Radio Jove project. However, INSPIRE is focused on observing natural and manmade radio waves in the audio frequency region. These are in the Extremely Low Frequencies, or ELF, band and range from 30 to 3,000 Hz. Paul demonstrated the VLF-3 receiver, which may be purchased from the INSPIRE project in kit form. We heard some of the sounds that were recorded by the receiver, including sferics and whistlers. One comment from the audience concerned the problem of ubiquitous 60 Hz powerline interference. The VLF-3 has a 60 Hz filter, but the only sure way to eliminate this interference is to move away from it to an electrically quiet location far from powerlines.

John Mannone, SARA Journal editor, gave a talk on an integrated approach to amateur solar radio astronomy. He discussed solar emission dynamics, the relationship the Sun has with the Earth and the appearance of solar phenomena at different frequencies from radio, through visible to x-rays. Of considerable importance to amateur radio astronomers are the vast amounts of readily and freely available professional data, which can be used in the correlation and confirmation of amateur observations. John’s accompanying paper in the conference proceedings includes many internet links that can be used to obtain such data.

Our last presentation on Monday was from Bruce Rout. Bruce was familiar to attendees of the 2010 Western Conference at Stanford University in California. At that conference he delivered a presentation on determining the size and distance of certain galaxies. Attendees of that conference will recall that Bruce was accused of "hand-waving" in his methods. Following the western conference, there was a follow-up discussion on the SARA Google listserver (http://groups.google.com/group/sara-list) about his papers. His presentation at the annual conference was an expansion of his previous presentation and provided additional specific detail concerning his methods for determining the structure and dynamics of spiral galaxies. There were no accusations of hand-waving this time. One attendee asked Bruce what steps he had taken to publish his concepts in professional journals and he replied that he could not get past the editors. I would like to challenge anyone to prove Bruce wrong. As the presentation ended, I heard someone shout, “There is no dark matter, it all is explained right here”.

During breaks and in the mornings and evenings we had free run of the NRAO grounds. One attraction was Grote Reber’s original 10 m radio telescope antenna (left), which he used in his private studies of radio astronomy. This antenna was moved from Wheaton, Illinois to Green Bank, where it is on permanent display.

The next day, Tuesday, Paul Oxley, who was elected vice-president at the SARA elections earlier that morning, gave a presentation on interfacing a motorized pan/tilt mount to planetarium software. He had several pan/tilt mounts on display, one with a Ku band dish antenna attached to it, and said that the mounts generally are used in security camera installations. They are available on the used/auction market from around US$50 to US$200. Some are quite large and heavy and shipping costs usually are more than the mount itself. Paul described the electronics interface as well as the hardware/software problems involved in accurate positioning and tracking with the mount, where azimuth rotations of a few thousandths of a degree per second are needed.

Francisco Reyes, a member of the Radio Jove Team, presented an overview of his work in the 1980s observing pulsars at 26.3 and 45 MHz. I was looking forward to his presentation because of my previous involvement in looking at the possibility of detecting pulsars at 20 MHz. Calculations by Victor Herrero, an active Radio Jove contributor, had shown that there would be extreme difficulty with the antennas normally used by amateur radio astronomers. This, plus the fact that the flux densities of many pulsars roll off (decrease) below around 100 MHz, indicated a very low chance of detection. I have to admit that, although the math indicated the difficulty, I was open to attempting detection anyway. However, Francisco’s presentation changed my mind. He described his 26.3 MHz antenna array made from 640 dipoles with an effective area of 16,000 square meters and a 45 MHz array of 580 dipoles with an effective area of almost 10,000 square meters. He was able to detect pulsars at 45 MHz during the daytime, although interference frequently corrupted the data. He was able to detect pulsars at 26.3 MHz only at night when interference levels were relatively low.

Francisco next discussed using a smaller antenna such as a single Yagi with an effective area of around 100 square meters, giving an effective area ratio of 1/160 compared to one of his larger arrays. With the same bandwidth involved in detection, the integration time would have to be around 21 hours. Since a pulsar would not be in view for that length of time, a series of observations would be required over a period of several days, and then the observations integrated using signal processing techniques. He outlined some of the other problems involved including timing accuracy, pulse dispersion, and higher galactic background noise temperatures at lower frequencies such as 20 MHz. Francisco made it clear that, although there are many problems to solve, new data processing techniques and better instrumentation could make pulsar detection by amateur radio astronomers possible at 20 MHz. As for my pulsar detection project, it is now on permanent back burner. Francisco’s paper in the conference proceedings includes all relevant equations and a description of his work in this area.

Whitham Reeve followed next with the second of his two presentations on geomagnetism. Tuesday’s talk covered the Simple Aurora Monitor, or SAM, geomagnetometer he uses in Anchorage, Alaska. He described the results of his observations over the last year, which included recording of geomagnetic sudden impulses and geomagnetic storms and disturbances caused by the Sun’s CMEs and coronal hole high-speed streams. He also provided comparisons of his data and magnetograms with the Alaska Magnetometer Chain and Geostationary Observational Environmental Satellites (GOES). The SAM is available in kit form with a new 3-axis version slated to be available in kit form within a few weeks of the conference.

Nick Gross from the Center for Integrated Space Weather Modeling in Boston, Massachusetts followed with a presentation on observing Sudden Ionospheric Disturbances (SID) with the SuperSID VLF Receiver. This receiver is available from SARA for around US$50. It requires a soundcard interface on a PC and operates in the frequency range around 10 – 48 kHz. Signal processing takes place in PC software. The SuperSID receives terrestrial transmissions associated with submarine communications. Solar flares cause SIDs, which in turn affect the received signal amplitude. SIDs are caused by the same solar phenomena that can cause geomagnetic storms as described in the previous presentation. Solar flares occur when the Sun’s magnetic field penetrates the Sun’s surface and produces sunspots. The magnetic field lines become tangled and disconnected, producing coronal mass ejections. When the field lines reconnect, energy is transferred to the Sun’s surface and a flare may occur.

After having lunch and standing for a group photograph, we were taken on a tour of the NRAO facilities by Sue Ann Heatherly, the Education Officer at Green Bank. We were taken though the various lab and shop areas where equipment is designed, built and maintained. NRAO does not use commercial off-the-shelf receiver equipment because there really is no such thing – everything is custom designed and built using NRAO’s extensive shop facilities on-site. We got to talk to one of the engineers involved with the “backend” equipment, that is, the signal processing equipment that is connected to the output of the low noise receivers at the antennas. The back-end equipment is custom designed using special processors and field programmable gate arrays (FPGA).

We also spoke with one of the engineers who takes care of the receiver “front end” equipment. He was working on an interesting receiver for 26.5 GHz, which has seven circular horn antennas mounted on an array of waveguide interfaces and in a cryogenically cooled fixture. This is a 7-pixel antenna as opposed to a single, 1-pixel antenna. He described the process required to open, disassemble and work on the antenna components and then reassemble, evacuate and cool it for deployment. Everything on this antenna was gold plated (literally). One waveguide assembly, about 15 cm long, was built using an interesting process. The outside of an aluminum billet was machined to the exact shape required on the inside of the waveguide. It was then placed in an electroplating tank for around 100 hours. The final step was to dissolve the aluminum from the inside of the waveguide using an acid solution, which dissolved the aluminum but did not affect the gold plating.

We also visited the main control room for all the radio telescopes on the site. It looked nothing like my observatory. There were no endless and tangled masses of coaxial cables and audio cables, blaring radios and a poorly performing Windows PC. Instead there were dozens of monitors/displays neatly arranged on consoles. Processing equipment and interfaces were in separate, shielded screen rooms. In fact, the entire console area, about 50 ft x 20 ft, was in a screen room. Radio astronomy is not what it used to be (I think).

After our tour we returned to the classroom for a presentation by David Fields on his Moby Dish. He had previously described this whale of a radio telescope at the SARA 2010 Western Conference. It consists of a large (4.5 m) white dish antenna (Moby Dish) and a camper equipment room (Pequod). The Pequod was wrecked when a tree fell on it in 2009 but it was allegedly rebuilt, a claim David made at the earlier conference; however, we were given no photographic proof. Our final presentation was by Jim Moravec, who described his work with young people in Colorado and his efforts to get them interested in science. In spite of the many obstacles he has had impressive results, some of his students going on to very successful careers in various science fields. His presentation mirrored others I have seen and heard over the last few years, and I have to say that it must be pretty rewarding to work in an education environment and see younger people overcome huge obstacles.

I very much enjoyed the SARA 2010 Annual Conference and I think everyone who attended did too. The people were great, the presentations were great, and the facilities were great. It was well planned and organized thanks to the efforts of the SARA administration. Until next time, . . . . . keep your eyes open and ears peeled.