Shestov, Sergei ; Zhukov, Andrei N. ; Auchere, Frederic ; Berghmans, David ; Loicq, Jerome

Poster presented at SDO Workshop on 2025-02-17

Abstract: The extreme ultraviolet High-Resolution Imager (HRI) of the EUI telescope onboard Solar Orbiter observes the solar corona in a ~5A passband near 174A with unprecedented high spatial resolution. We perform radiometric cross-calibration of the HRI and the EUV channels of the Atmospheric Imaging Assembly (AIA) telescope of the SDO in order to allow further mutual analysis of the observational data. We apply differential emission measure analysis using quasi-simultaneous images in 7 spectral channels – HRI and 6 AIA – and compare the real and the simulated images on the per-pixel basis across the mutual field-of-view. The comparison suggests that the real HRI images have a 60-80% larger signal than predicted by the DEM analysis. While the DEM analysis is known to be error-prone, a good re-production of EUI images justifies the approach. The observed difference in real/simulated signal suggests either AIA absolute calibration or EUI absolute calibration is off. We also found that adding the HRI signal to the AIA-based DEM inversion procedure brings information about moderate ~1MK plasma. We discuss how mutual observations can be used to better understand the physics of individual events or structures.

Keyword(s): EUI ; Solar Orbiter ; calibration ; SDO ; AIA
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