On-sky results from the night of February 8, 2025, with the GS algorithm for slow focus tracking in closed loop. Raw FCS positions are also shown, in which the four moments when an intentional focus was introduced can be clearly identified. The mean and standard deviation of focus values obtained by GS neglecting the first 100 s, when the loop was still converging, were, respectively, −22 and 71 nm rms. The negative mean was expected, since during the experiment the out-of-focus movements were always made in the same direction (negative focus).