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SPIRou / Infrared SpectroPolarimeter

Image stabilization during observations

The SPIRou Image Stabilization Unit (ISU) in action at 50Hz: the left panel shows the image of the artificial star kept well centered on the instrument entrance aperture while the star itself is moving randomly by as much as 0.5’’ rms over the exposure, whereas the right panel shows the ISU correction needed to maintain the artificial star well centered (green '+' signs for the 50 most recent corrections over the last second). Sudden image shifts occurring every minute (at t=41s in this movie) simulate the decentering effect of the wind, which the ISU is found to correct well. In average over the whole exposure the image of the artificial star is found to be centered on the hole down to a precision of 0.005'' to 0.01’’ rms, 5-10x better than the technical requirement.
(©S.Baratchart - IRAP/OMP)