Tomography of the solar corona. II. Robust, regularized, positive estimation of the three-dimensional electron density distribution from LASCO-C2 polarized white-light images

Solar rotational tomography is used to determine the three-dimensional electron density distribution of the solar corona from 2.4 to 6.0 R _⊙. The robust, regularized, positive estimation method, described in a previous paper, is demonstrated on test cases and on LASCO-C2 data. Because the solar rotational pole is inclined to the plane of the ecliptic by about 7°, the tomographic inversion requires a full three-dimensional treatment instead of a series of two-dimensional inversions. The LASCO data are taken from the first Whole Sun Month, which was a period of low solar activity.