Update 23rd April 2006 Again Spitzer is a good signal, currently received on 8413.61880 at 22:22 GMT.
Update 22nd April 2006 The Spitzer space telescope has been copied on 8413.619MHz at 22:22GMT with very slight Doppler as per the FFT screen shot below. Its close to the Earth at only 29988091.8 miles, so doesn't really count as DX. The signal should be much stronger, but at the time of reception the elevation is low and the dish is looking through two sets of trees. Spitzer was launched on the 25th August 2003.
Where is Spitzer pointing? When the spacecraft appears end-on it is most likely downlinking data to Earth, and is in an ideal position to detect.
The FFT Image gallery below shows some of the signals received from the Spitzer Space Telescope over the years.