5863 20221021151123.0 CTALK-2022-0082 Berghmans, David First Perihelion of EUI 2022 2022-09-12 Oral contribution O23 of the conference abstract book On March 7 2022 with Solar Orbiter at a distance of 0.50 AU to the Sun and crossing between the Sun and Earth line, the Extreme Ultraviolet Imager (EUI) with its High Resolution Imager in EUV (HRI-EUV, 17.4 nm) created a 25-panel mosaic of raw exposures covering the entire disc of the Sun. Using this dataset we discuss the biggest challenges of calibrating EUI data in general and HRI-EUV data in specific: from dark and flat calibration, artefacts on the detector in the shape of gummy bears, to the difficulties in combining low and high-gain images into high dynamic range combined gain exposures. Finally, we show how the calibrated images were combined into the highest resolution full-disc solar corona image in Extreme ultraviolet light ever. This combined mosaic image was produced in first instance for outreach purposes. However, some science use and multi-instrument cross-calibration can also be anticipated and we will discuss the limitations and opportunities for this. STCE Sun corona EUI Antolin, Patrick Auchère, Frederic Barczynski, Krzysztof Aznar Cuadrado, Regina Chitta, Lakshmi Pradeep Gissot, Samuel Harra, Louise Janvier, Miho Kraaikamp, Emil Long, David Mierla, Marilena Parenti, Susanna Rodriguez, Luciano Schühle, Udo Stegen, Koen Verbeeck, Francis Zhukov, Andrei EUI team, X 8th Solar Orbiter Workhop david.berghmans@observatoire.be Contributed CTALKCONT