[This plot is updated every minute.]

The plot shows the last 24h of observation.  The two prominent interference patterns are from (on right) the supernova remnant
Cass A, (situated in our own Galaxy) and (on left) the active galaxy Cygnus A, at a distance  ~1/30th of the way to the 
edge of the Universe.  The Sun, currently to the right of these two sources,  also produces a pattern which can vary greatly from day to day, depending 
on current sunspot activity. (The periodicity of the interference patterns is determined by the declination of the sources.)

Description of the Receiver.

The signal from one Yagi is put through a 180 deg switch, combined with the signal from the other Yagi,
and fed into a "TV Dongle" tuned to 151.5MHz and plugged into a Raspberry Pi 2.

The Raspberry Pi -
i)    provides the drive waveform for the 180 deg switch;
ii)   uses the TV dongle to sample the signal at 900 ksample/s, converts it to baseband (0-450 kHz), 
      providing 8-bit Cos and Sin samples of the resulting  +-450 kHz bandwidth signal;
iii)  calculates the total power of each sample, both with and without phase-sensitive demodulation;
iv)   integrates both values for ~5s and records the ratio (times 10**4) in a 'round-robin' database;
v)    produces a plot of this ratio for the last 24h period.
The plot is a (scaled) measure of the amplitude of the correlated component in the signal from the two Yagi antennas.