POLAR: Instrument and Results

We describe the design, performance, and results of a polarimeter used to make precision measurements of the 2.7 K cosmic microwave background. In the Spring of 2000 the instrument searched for polarized emission in three microwave frequency bands spanning 26–36 GHz. The instrument achieved high sensitivity and long-term stability, and has produced the most stringent limits to date on the amplitude of the large angular scale polarization of the cosmic microwave background radiation

Polarization observations of DQ Her stars and other cataclysmic variables

© Royal Astronomical Society. Linear and circular polarizations are presented for the DQ Her stars FO Aqr, AE Aqr, EX Hya, AO Psc and V1223 Sgr and for 17 other cataclysmic variables. Upper limits (~0.1 per cent in circular) are set to any periodic varia- tions in the polarization for the DQ Her stars. The source of the large periodic intensity variations in some of these stars is investigated in the light of the null results. Cyclotron radiation is ruled out. AE Aqr may be circularly polarized at the 0.05±0.01 per cent level. Previous claims for the detection of circular polarization in HL CMa and V603 Aql are not confirmed