Left: post-fit residuals for a pulsar at a distance of 200 pc located at the pole of the ecliptic after fitting for position and proper motion but not for parallax. Remaining structure in the TOAs is clearly visible. Right: error in the timing parallax as a function of the ecliptic latitude β for weekly timing of a pulsar to a TOA with 10 ns error. The blue and red lines correspond to 5 years and 10 years of timing, respectively.