Phase curve of the (22) Kalliope and Linus system. The reduced brightness H₀ versus the phase angle α is plotted. Calibrated photometry from Gehrels & Owings (1962), Scaltriti et al. (1978), Surdej et al. (1986), this work, and the Gaia DR3 was used. The observed curve (×) is plotted in colour (according to the Julian date) and the synthetic (+) is in yellow. The range of α is from 2 to 22°. There is an unreduced and n_lc = 1892, with systematics up to 0.05 mag. The ‘scatter’ of points is mostly due to the light curve, which is fitted by our model. Our measurements with α ~ 13°, taken in the Cousins R band, are in agreement with our model (0.001 mag).