AAS 200th meeting, Albuquerque, NM, June 2002
Session 34. Understanding Solar Magnetism, the Advanced Technology Solar Telescope
SPD Topical Session Oral, Tuesday, June 4, 2002, 8:30-10:00am, 10:45am-12:30pm, Ballroom B

## [34.06] Challenges of Measuring Coronal Magnetic Fields

P. Judge (HAO)

Measurements of components of the vector magnetic field in the solar corona can potentially yield information critical to our understanding of coronal structure, dynamics and heating.

I will review techniques for making such measurements, in particular those that can be applied outside of active regions. Forbidden coronal emission lines appear to have the highest potential to address outstanding problems in coronal physics, especially those related to the storage and release of magnetic free energy. Measurements of the full Stokes vector of M1 lines of magnetic dipole (M1) character can constrain {\em both} the line-of-sight field strength, B\|, through the longitudinal Zeeman effect seen in Stokes V profiles, {\em and} the direction of the vector field projected onto the plane-of-the-sky, through the analysis of resonance scattering-induced linear polarization seen in Stokes Q and U, in the so-called strong field'' regime of the Hanle effect. Coupled with additional data and models, accurate polarimetry can reveal information on coronal magnetic fields, including current systems, unobtainable by other means available now or in the near future. I will discuss the current challenges presented by such measurements for both for the ATST project and in more general terms.