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Jupiter's Radio Signals By James L. Ibaugh, AA3C Anyone for Amateur Radio Astronomy? The first time I heard signals from Jupiter (aka Jove), I thought it was long distance noise from a tropical storm. I almost ignored it, except I questioned why I was hearing long distance storm noise but no ham signals from the same WSW direction on a completely dead 21MHz. The noise had a strange structure to it, not like the normal lightning storms I was used to hearing on HF, it had rhythm! It was the fall of 1974 about 10PM and I swung my Mosley Triband beam between south and west, the noise peaked out at about 255 degrees Azimuth (AZ, True of North, not magnetic). GEOMAGNETIC DECLINATION BY ZIP CODE I was using a Hallicrafters SX-115 ham band only receiver so I QSY'ed (moved down) to 14MHz and it was just as dead as 21MHz, but there was no strange noises on the 20 meter band. The reason for both bands being dead was the sun spot cycle was in it's lowest point. Low points are good for satellite work because the ionosphere is transparent to HF and VHF signals. Next peak was in ~1986. It occurred to me that my receiver may be getting a gassy tube. I then asked the *BRIGADEAR* (XYL Shari) if I could use her Hallicrafters SX-100 HF general coverage receiver (500 kHz to 32 MHz) and compare the results. I disconnected my beam coax from my receiver TR switch and stretched it across the room to her SWL (Short Wave Listener) station, connected it to the SX-100's preamp and tuned in 21MHz. To my surprise the signal was stronger on her SX-100 at S2 on the S-meter and it was only S1 on mine! That's a 3 dB difference. Both receivers had identical wide band low noise +20dB gain RCA Nuvistor front end (external) RF pre-amplifiers. Then I rationalized, maybe the noise signal is getting stronger. Since Shari's SX-100 was easy to tune, I QSY'ed down the HF band to 20 MHz and when I did the noise was S2.5 which was 1.5 dB higher. I tried 19MHz (S2.0), 18MHz (S1.5) and at 17MHz it was even with background noise and some QRM splatter from a short wave broadcast station. I wrote it all up in my combined log book/technical notebook. I had been working on an academic paper about deep space gamma ray bursts in my spare time and spent many hours at the Grundy Observatory on Franklin & Marshall College's Baker Campus in Lancaster. On a late fall evening I was doing some research there on documentation of the star Constellation Canes Venatici and star Constellation Hercules. My old RCA colleague was there, Tony Destazio (PHD Astronomy from U. of Hawaii) ask me if I would like to look at Jupiter through F&M's best telescope. I jumped at the chance. He already was looking at Jupiter and taking photos for 15 minutes. He mentioned that Earth is the closest to Jupiter that night then it will be for the next 12 years because Jupiter has a very elliptical orbit around the sun. Even though Earth passes Jupiter's solar azimuth each and every year, the difference in orbital positions are huge. Tony also mentioned that the Radio Astronomers are busy studying the High Frequency signals generated by Jupiter's magnetic fields. That took my breath away. I managed to blurt out the question, “What might the Azimuth of Jupiter be right now?” It was about the same time I heard the noise on HF bands last night. Tony pointed to a newish nixeytube digital meter showing the Azimuth in orange numbers, “255.37 DEGREES. My knees went weak. The last right hand two digits changed quickly as the scope's automatic tracking system kept the large planet in the center of the photographic plate. I asked, just what do these HF radio signals sound like? He said he never heard one. Tony then walked over to a tall pile of Astronomical Journals and plucked one out of the middle of the stack and glanced through the index to find an article. He found it and handed the journal to me and placed a cardboard marker in the stack for it's return. The article described the discovery of Jovian (Jupiter's) radio signals in 1955 by scientists Dr. Bernard Burke and Dr. Kenneth Franklin of the Carnegie Institute in Washington D.C. They discovered that the planet Jupiter was a strong 22 MHz source of radio waves (that is the only frequency that they were using). Jovian radio storms, first noticed in 1955, are beamed to Earth by natural radio beam generator near Jupiter's magnetic poles. Jupiter's radio beam generators are natural, made of plasmas (ionized gases, mostly Hydrogen) and magnetic fields. High speed streams of magnetized plasma flowing downward into Jupiter's polar regions emit radio waves. "Cyclotron Maser Mechanism" as the process is known. When this mechanism is operating, Jupiter can “outshine” even the sun as a radio source. These cyclotron maser generators are powered, in part, by Jupiter's large moon Io. Volcanoes on Io hurl electrically conducting gas into Jupiter's magnetosphere (the region of space controlled by Jupiter's magnetic field), where it collects in a doughnut-shaped region, the large "Io torus." As Io travels around Jupiter, it plows through the torus and makes waves. These "Alfven waves," guided by magnetic forces, carry about 40 trillion watts of power to Jupiter's polar regions. Spectrograph: U.of Fla. R.O. If only 1% of the plasma's electrical current is converted to RF power, that is 400 billion watts of RF power between ~16 MHz to ~25 MHz! 400,000,000,000 WATTS is not exactly a peanut whistle on the HF band in this solar system! Jupiter's Io-controlled radio emissions are not broadcast in all directions. The cyclotron maser generators beam has the shape of a wide hollow cone. If Earth is inside the cone, we hear nothing. If Earth is outside the cone, we also hear nothing. When Earth is in the narrow edge of the cone, we can hear some strong radio bursts. Speaking of hearing Old Jove's Voice, Click Here. This voice was slowed down by a factor of 128 to get it into human hearing range and was a type S-Burst signal. S-Burst SLOW Graph: U.of Fla., R. O. Here is the normal speed Type S-Burst, Click Here. This was the sound I first heard back in the fall of 1974* when Earth and Jupiter had a close encounter. You may have heard old Jove in other close passes in 1950, 1962, 1974*, 1986, 1998 or 2010. It is best heard during or close to (with in a year or two of) a solar cycle minimum as in 1951, 1962, 1973*, 1984, 1995 or 2006. If you would like to see Jupiter with your own bare naked eyes, it NOW is the third brightest object in the sky besides the sun and the moon. <>JUPITER's Location in PM Dec 9, 2010 <>From 40.09N 76.41W QTH, LOCAL TIME 7PM 1900HRS 191ºAZ 45ºELivation 8PM 2000HRS 210ºAZ 41ºEL 9PM 2100HRS 227ºAZ 34ºEL 10PM 2200HRS 240ºAZ 25ºEL 11PM 2300HRS 252ºAZ 14ºEL 12PM 2400HRS 262ºAZ 3.3ºEL ..0014HRS 264ºAZ 0º EL, BELOW HORIZON <>Jan 9th, 2011 Jupiter Location in PM 5PM 1700HRS 187ºAZ 47ºEL 6PM 1800HRS 207ºAZ 44ºEL 7PM 1900HRS 225ºAZ 37ºEL 8PM 2000HRS 239ºAZ 28ºEL 9PM 2100HRS 251ºAZ 17ºEL 10PM 2200HRS 261ºAZ 6.5ºEL 10:30PM 22300HRS 266ºAZ 0ºEL Viewing works only on clear cloudless nights. 9PM(2010)=227ºAZ and 9PM(2011)= 251ºAZ Jupiter moved only 24ºAZimuth (17ºEL) in 30 days, less than one degree AZ per day. The 24º AZ change is the increased distance to Jupiter next month. The Earth moves through 360º solar azimuth while Jupiter moves only through 30º solar azimuth per one earth year. Slow poke. Both orbits are significantly elliptical with Jupiter having a 12 earth year solar orbit. Jove's size, reflectivity, and close distance to Earth (355 million miles once every 12 years) make it a very bright object in the sky. Earth is now moving away from old Jove at ~14,000 miles per day (583.333MPH). Visit the web page WWW.AMSAT.ORG for tracking information, tools and software. Jupiter rotates once every 10 hours and the cone rotates with it like a lighthouse beam. To catch a radio storm you have to know (1) when Earth will be aligned with the edge of the cone and (2) when Io is in the right position to pour electrical energy into the radio storm zone. Every ten hours there are two chances to hear Jupiter as Earth passes both sides of the radio cone. Once you detect the signal record the date and time, ten hours later the same signal should be heard as long as Jupiter is above the horizon. When Jupiter is behind the Sun or moon it's no go for big old Jove's signal. Jove can be heard during day light hours and in cloudy weather. Most HRO's do not have elevation control of their HF beams, just point in the general azimuth. Try it with a wire antenna. I've heard Jupiter with a 100 foot long wire and the *Brigadear*'s R.L. Drake SSR-1A battery powered solid state general coverage SWL receiver (fall of 1996). There is a government sponsored program for schools and youth groups to build, setup and operate their (or your) own Jupiter Radio Observatory (not limited to Jupiter). NASA's RADIO JOVE PROJECT. A special Radio Astronomy receiver kit is for sale to non-hams who do not have access to a good HF receiver. A free informative PDF manual to the Radio Astronomy Receiver Kit Click here. More information about Radio Jove Project. For the non-hams, FREE antenna PDF manual JOVE RJ1.2 Dual Dipole Antenna Array. This antenna manual contains a useful chart (Fig. 1.5) “Elevation angle of Jupiter at transit, observers at different northern latitudes from 2003 to 2013.” It has good wire antenna information for DX'ers. The free radio astronomy software for use with their receiver kit or your ham receiver is available for Windows 98/NT/2000/Xp/Vista (works AOK on my Win7.0): RADIO-SkyPipe 2.1. FREE! SkyPipe 2.1 works with your computer's sound card, with or without Internet connection. Internet connection if want to share data on line. It works on other projects better than most of my paid commercial scientific chart recorder programs I have used in the lab before, like LabChart-V, etc. Jupiter's Radio Image on 22 cm band. NASA. Disclaimer: Even though we are approaching the next solar sunspot peak 2012 to 2013, there are times that the Maximum Usable Frequency (MUF) falls well below the 16MHz to 25MHz range of Jupiter's signal emissions. Even when the MUF is in that range the characteristic sound of Jovian Radio Burst Emissions may be heard above Earth's weak radio signals and static noise. Results may vary with each radio setup, time, date, year and degree of patience. This adds new meaning to the newish phrase Radio Amateur Astronomy. From a star gazer to a star listener. Have fun snagging Jupiter DX. 73's de AA3C. Jim A A 3 C @ A R R L . N E T