DA Biesecker (Univ. of Birmingham); CM Korendyke, D Wang, RA Howard, GE Brueckner, DJ Michels (NRL); A Lecinski (HAO); Sarah Gibson (NASA GSFC/NRC); Lika Guhathakurta (NASA GSFC/Catholic Univ.); PL Lamy (LAS-Marseille); R Schwenn (MPI-Lindau)
Measurements of polarized brightness (pB) of the solar corona have been used by researchers with other coronagraphs, both ground and space based. Many tools have been developed for using pB to derive the electron density in the corona. It is also useful for separating the K and F coronae, at least to heights of 5 or 6 solar radii. For these reasons, it is useful to make similar measurements of pB with the coronagraphs of the SOHO/LASCO instrument. The LASCO C2 and C3 coronagraphs are typically used to take one image sequence per day from which pB can be obtained. The C2 coronagraph images the corona from about 1.5--6 solar radii, the C3 coronagraph from about 3.7--30 solar radii. We show pB from the C2 and C3 coronagraphs. Thus pB is measured all the way out to 30 solar radii. Then, for calibration purposes, this is compared to pB obtained from the Mauna Loa MkIII coronagraph. Where the assumption that the polarized signal is due primarily to the K corona is valid, models can be used to derive the coronal electron density. Using some simple assumptions, we also use these measurements of pB to begin to separate the F and K coronae. A complete separation of these two components will allow measurements of the electron density all the way to 30 solar radii.
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