HR: 14:45h
AN: SH23C-05    [Abstracts]
TI: Magnetograph Saturation: Comparison of WSO and SOLIS
AU: * Svalgaard, L
EM: leif@leif.org
AF: ETK, 6927 Lawler Ridge, Houston, TX 77055 United States
AB: The calculation of potential magnetic field models of the magnetic field in the higher corona and its extension into interplanetary space depends on accurate measurements of the magnetic field in the photosphere. To fit the observed interplanetary magnetic field and the observed sector boundaries various "corrections" have been applied: addition of extra polar fields to compensate for the difficulties in measuring the weak line-of-sight true polar fields, and correction for"magnetograph saturation" for Babcock-type double-slit magnetographs. The latter correction is typically either a factor between 4.5 and 2 depending on distance from disk center (Mt. Wilson-type correction) or a constant factor of about 1.8 (Wilcox Solar Observatory). The new NSO-SOLIS magnetograph now operating atop of Kitt Peak does not suffer from magnetograph saturation. Comparison between WSO mean field measurements and SOLIS disk averaged measurements show that SOLIS = 1.70 * WSO. This is close to the WSO saturation factor and destroys the agreement between potential field models and the IMF radial component calculated with a typical saturation factor of about 4 for disk-averaged fields. We are back to the old problem of the calculated flux beeing to small by a factor of two.
DE: 2169 Sources of the solar wind
DE: 7524 Magnetic fields
DE: 7529 Photosphere
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly