Published online by Cambridge University Press: 14 August 2015
During the course of two observational programs to search for magnetic fields in white dwarfs (Angel and Landstreet, 1970a; Kemp, 1970), it was discovered by Kemp and Swedlund (Kemp et al., 1970b) that the continuum optical radiation from the λ4135 type white dwarf Grw + 70° 8247 is circularly polarized. This circular polarization was measured in a broad band from about 4000 to 7000 Å a number of times; in this band the circular polarization does not appear to vary from its mean value of 3.29% with an amplitude of more than about 0.1% (or 3% of the measured mean polarization) on any time scale from 24 seconds to 2 weeks (Angel and Landstreet, 1970b).