Comparison of Line-of-Sight Magnetograms Taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager

摘要: We compare line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) Michelson Doppler (MDI) Heliospheric (SOHO). The magnetic signal inferred calibrated MDI data is greater than that derived HMI by a factor of 1.40. This varies somewhat with center-to-limb distance. An upper bound to random noise for 1′′ resolution 720-second 6.3 Mx cm−2, 10.2 cm−2 45-second magnetograms. Virtually no p-mode leakage seen in magnetograms, but it significant 12-hour 24-hour periodicities are detected strong fields newly full-disk have been corrected zero-point offset underestimation flux density. 26.4 one-minute 16.2 five-minute observed four-arcsecond resolution. variation over Sun’s disk found likely due different optical distortions left- right-circular analyzers, which allows granulation leak as noise. Saturation sometimes sunspot umbrae caused low intensity limitation computation. magnetic-field synoptic charts appears be fairly uniform entire map. 2.3 5.0 charts. No evident periodicity