Comparison of the Magnetic Field Inferred by SO/PHI-HRT and SDO/HMI

Abstract

<p>Onboard the Solar Orbiter spacecraft is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a high resolution telescope (HRT) and the full disk telescope (FDT). The instrument is designed to infer the photospheric magnetic field through differential imaging of the polarised light emitted from the Sun. It is the first magnetograph to move out of the Sun-Earth Line, providing excellent stereoscopic opportunities with other ground and space based instruments. Of particular interest is the comparison between SO/PHI-HRT and the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI). They probe the same magnetically sensitive line of Fe1: 6173 Å and have the same aperture diameter. In March 2022 Solar Orbiter crossed the Sun-Earth line, providing an excellent opportunity for a comparison. Here a comparison between the magnetic fields, both line-of-sight and all three vector components, inferred by SDO/HMI and SO/PHI-HRT during the conjunction, are presented. </p>

Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun Corona

“…These observations are a part of the Solar Orbiter Observing Plan, named R_SMALL_HRES_HCAD_RS-burst (Zouganelis et al 2020), and are available through the Solar Orbiter Archive. 9 The magnetic field maps were obtained by the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager on board the Solar Orbiter spacecraft (SO/PHI; Solanki et al 2020), which samples the four Stokes parameters at five wavelength positions within the Fe I 617.3 nm line plus a sixth one of its nearby continuum (reduction and calibration of SO/PHI data are detailed in Kahil et al 2022aand Sinjan et al 2022. 10 The data were recorded from UT 04:17 to UT 07:12, with a cadence of 300 s, an image scale of 0.5″ pixel −1 (spatial resolution corresponding to 2 pixels ≈ 212 km on the Sun).…”