calibsys correction, in mag.
The calibsys correction consists in shifting the zero-point of the individual distance scales that we identified in the catalogue to align them with our standerd set. We suceeded to associate most measurements to a calibsys, in the other cases we could not find in the original paper an unambigous description of the distance scale, in some cases because the listed measurements were clearly not bound to an homegeneous system (e. g. in the case of some compilations). No correction is applied in these latter cases. The most populated calibsys is Freedman+2001. For each calibsys intersecting calibset on more than 5 objects, a zero-point correction is computed.
dataset correction, in mag.
The dataset correction, to apply on individual series of measurements is determined by comparing each series to all the rest of the catalogue after applying the calibsys and the previously adopted dataset corrections. Unlike the calibsys correction, the determination of dtc is a supervised process, which is incremental and iterative. For all the dataset having a sufficient intersection with the rest of the catalogue, a correction is suggested, together with the significance level. Then the datasets displaying the most significant offset are carefully examined. If a zero-point correction is adequate, a dataset correction is adopted, and all the calibsys corrections and suggested dataset correction are automatically re-adjusted.