6276 20230131135054.0 POSTER-2023-0018 Gissot, S. Performance of the Extreme Ultraviolet Imager (EUI) High-Resolution EUV Imager (HRI-EUV) telescope: from pre-flight calibration to first in-flight images 2022 2022-09-12 The High-Resolution Extreme Ultraviolet imager (HRI-EUV) is the EUV telescope with high spatial resolution of the EUI instrument. It is based on an off-axis Cassegrain design optimized to observe the solar corona at a wavelength of 17.4 nm. Following the calibration campaigns of its optical components, i.e. entrance and focal Al foil filters, multilayer coated mirrors, and CMOS APS detector, an end-to-end EUV radiometric calibration of the HRI-EUV telescope was performed in April 2017 using the synchrotron radiation of the Metrology Light Source (MLS) electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB) in Berlin. We report the results of the HRI-EUV optical components and instrument calibration campaigns, from which we derive the instrument performance parameters. We will also report in-flight performance as assessed during the commissioning calibration operations, based on acquisitions in dark conditions and using the internal LED calibration source, as well as on the analysis of EUV images acquired since May 12th, 2020. STCE Berghmans, D. Auchère, F. Kraaikamp, E. Stegen, K. Verbeeck, F. Giordanengo, B. BenMoussa, A. Schühle, U. Teriaca, L. Aznar Cuadrado, R. Harra, L. Long, D. Smith, P. Delmotte, F. Rebellato, J. Halain, J.-P. Gottwald, A. Laubis, C. 8th Solar Orbiter Workhop, Belfast (UK) samuel.gissot@observatoire.be CPOSTER