Effect of the occulting disk on 640 s FSI 17.4 nm exposures taken on 2021 March 21. Left: view without the occulting disk at 01:48:45 UT (logarithmic color scale). The position of the solar disk is marked by the white circle. Right: view with the occulting disk at 00:45:45 UT (linear color scale). The black hexagonal shape marks the vignetting cut-off. A matching exposure dark frame was subtracted from each image. The intensity profiles at row 1536 are displayed on the same logarithmic scale for comparison.