The WSRT northern sky survey at 330 MHz has detected very large
scale polarization structures at low and intermediate Galactic
latitudes which are thought to be produced by spatially varying
galactic Faraday rotation of the intrinsic polarization of the
galactic nonthermal continuum radiation.
These
polarization features are apparent on spatial scales ranging from 
to several degrees. The detailed study of these features
requires total power measurements and large scale mosaicing in total
intensity and linear polarization at three frequencies at or below 1.4
GHz. Such a study would provide constraints on the electron density
and the magnetic field in the Galaxy, which in turn could be used to
produce a specific model of the hot ionized medium phase of the ISM.
A byproduct of the investigation would be a high resolution look at the magnetic field structure, corrected for Faraday rotation, of the Galactic nonthermal continuum, which would provide insight into Galactic dynamics and the interaction between SNR and H II regions and the ISM. A high resolution spectral index study of the Galactic continuum emission would help answer questions about the source of cosmic rays. Comparison of a high resolution continuum image and the FIR emission could shed light on the details behind the very tight FIR-radio-continuum correlation seen in other galaxies.
These projects require the E configuration for high brightness sensitivity and good mosaicing quality, and some additional frequency coverage between 300 MHz and 1.4 GHz.