Normalized S/N of the V² measurements versus V² for the observation of HD 3360 of 2016 Sep 30 (blue dots) and our model of S/N estimation considering the mean Strehl ratio (3.5%, red solid curve), the worst one (2.6%, lower black solid curve), the best one (4.3%, upper black solid curve) and without the amplification noise (green dashed curve). The last case is obtained with the mean Strehl ratio.