[RFI] As if BPL weren't enough...

[W0UN -- John Brosnahan]

At 09:02 PM 2/20/2004, you wrote:

>Don't bother to call the FCC about this one --
>http://science.nasa.gov/headlines/y2004/20feb_radiostorms.htm?list129291

Tom--

I spent five years at the University of Colorado Radio Astronomy
Observatory--monitoring the Jupiter/Io effect.   The discovery was
actually made by an Australian but he used the data from Colorado.
But this was before I got there (I was there from 1973 to 1978).

The data is not as valuable now that the two Voyager satellites went
to Jupiter and took data "in situ".  But still quite interesting.  Our group
had the radio astronomy experiments on the two Voyager probes.
The noise peaks when a line from earth to Jupiter makes either a
90 degree or a 240 degree angle with the line from Jupiter to Io.   So
you need to know this angle to have a good prediction on the chance
to hear Jupiter.  Surprisingly it is 90 and 240 not 90 and 270.  Basically
the action from Io to Jupiter is like a dipole and the peak happens
when we are broadside to this dipole.  But the pattern is skewed--
which I attribute to a lack of a balun!    ;-)   A point I make when I give
talks about antennas--or about radio astronomy!

Nice to see the site--I used to now people down there--and I guess
Pat, K0OO (aka KG4OO) spent some time there in the 80s.

It is fairly easy to hear with a decent Yagi on 15M, assuming Io
is in the right position.   The most prevalent noise sounds like
the surf.  It is easily distinguished from random noise because
it is highly circularly polarized due to the strong magnetic field of
Jupiter.

73  John   W0UN

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