The processing includes the following steps common to both RR Lyrae and Cepheid
stars (see Fig. 1 in Clementini et al. 2019):
Derivation of period and harmonics (amplitudes and phases) by non-linear
Measurement of light curve parameters (mean magnitudes, amplitudes, epochs
of maximum light, etc.),
Consistency check of the periods derived from the 3 bands (G, GBP,
Search for secondary periodicities.
The following additional steps are then applied to sources confirmed as RR Lyrae stars
(see Fig. 2 in Clementini et al. 2019):
RR Lyrae Double-mode search,
Non-linear double-mode modelling,
RR Lyrae Classification and validation,
Stellar parameters derivation: metallicity,
Stellar parameters derivation: absorption in the G-band for RRab stars.
and the following additional steps applied to sources confirmed as Cepheid
variables (see Fig. 3 in Clementini et al. 2019):
Cepheid Multimode search,
Cepheid Type identification,
Type II Cepheid Subclassification,
δ Cepheid Mode identification,
ACEP Mode identification,
Cepheid Classification and validation,
Stellar parameters derivation: metallicity for δ Cepheid variables with period
shorter than about 6 days.