•Radio observations still the only means for reliably measuring coronal magnetic field strengths anywhere on the solar disk
•Measures temperatures on surface of constant field strength – directly see regions of strong heating
•Because emission is optically thick in regions of strong
field, we get 3D information on
fields
•Relatively insensitive to density, therefore complements
EUV/soft X-ray observations which
are dominated by density contrast
•Important role in testing techniques for extrapolating surface fields into corona