Linear polarization measurements of the AM Herculis objects H0139-68 and E1405-451

Linear polarization observations of the optical counterparts of H0139-68 and E1405-451 are reported. Polarization pulses near photometric minimum were detected in the V band for both X-ray sources, confirming their classification as AM Her objects. A secondary linear polarization pulse was also observed approximately half a cycle later for H0139-68; this is the first such detection among the AM Her class and suggests that cyclotron emission is being produced at both poles of the magnetic white dwarf. There is also evidence for weak linear polarization (approximately 2 percent) at all binary phases for H0139-68 and E1405-451, indicating an additional component in their continua.