No image quality change between nominal and ±4◦ offsets. Compared are EE50 (top panel) and EE80 (bottom panel) for nominal and offset positions, combining data from RGS000 and RGS180. The central grey boxes at 1300 nm, 1500 nm, and 1800 nm correspond to the encircled energy measured with the grism wheel in nominal position. The boxes to its left and right correspond to measurements done with −4◦ and +4◦ offsets, respectively. An artificial wavelength shift was applied to increase readability. For clarity, the plot is restricted to the encircled energy estimate using the asymmetric-Gaussian profile.