SIMBAD references

We have obtained UBVRI polarization measurements of 26 post-asymptotic giant branch (post-AGB) candidates and related stars. The extremely metal-poor post-AGB star HR 4049 has been observed several times. In most cases we find the objects to be intrinsically polarized. The polarization measurements presented in this paper indicate asymmetric circumstellar dust shells and disks around these stars. For some objects the steep percent polarization λ-dependence and large degree of polarization suggest that scattering by circumstellar dust grains may be responsible for the observed polarizations in the blue.