short communications
In a previous paper [Langs (1985). Acta Cryst. A41, 578-582] formulae were derived to reduce the magnitudes of structure-independent spurious peaks which appear in translation syntheses. The present note describes how crystallographic symmetry may be exploited to simplify these calculations by a factor of a hundredfold. The solution maximum produced by this new formulation is often more than ten times larger than the largest spurious background peak.