Polarization Measurements on Three Intense Radio Sources

The radiation from three intense extra-terrestrial radio sources, in Cygnus, Cassiopeia and Taurus, has been tested for polarization at a wave-length of 1.9 m. The results show that, in the flux from the sources in Cygnus and Cassiopeia, there is no plane polarized component greater than 1 per cent and no circularly polarized component greater than 4 per cent. In the case of the source in Taurus (the Crab Nebula) the corresponding limits are $$2\frac{1}{2}$$ per cent and 4 per cent respectively.