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If it was possible to measure parallaxes for high redshift objects, the distance so measured would be the parallax distance DP (Weinberg 1972, pp. 418-420). It may be possible, one day, to measure parallaxes to distant galaxies using gravitational lensing, although in these cases, a modified parallax distance is used which takes into account the redshifts of both the source and the lens (Schneider, Ehlers & Falco 1992, pp. 508-509), a discussion of which is beyond the scope of these notes.