Zenital r₀ at 500 nm estimated on MUSE (filled circles, 40 data points) and SPHERE/ZIMPOL (empty circles, 27 data points) using three methods: PSF fitting, SPARTA, and MASS/DIMM. Top: r_0, SPARTA versus r_0, FIT. A different linear tendency is found for MUSE (plain line) and SPHERE/ZIMPOL (dashed line). Shaded areas show the standard deviation between data points and the best linear fit. Middle: r_0, SPARTA and r_0, FIT versus r_{0, MASS/DIMM}. Two linear tendencies are identified for SPARTA, and only one for PSF fitting. Bottom: histograms of seeing estimated with the three methods on both instruments. Dashed vertical lines show median values of 0.46″ (SPARTA), 0.69″ (MASS/DIMM), and 0.83″ (PSF fitting).