10.5.4 Processing steps

The processing includes the following steps that are in common for both Cepheid and RR Lyrae stars (see figure 1 in Clementini et al. 2019):

1. 1.

   derivation of period and harmonics (amplitudes and phases) by non-linear Fourier analysis;

2. 2.

   measurement of light and radial velocity curve parameters (intensity-averaged mean magnitudes, mean radial velocity, amplitudes, epochs of maximum light for the photometry, epoch of minimun for the radial velocity, etc.);

3. 3.

   consistency check of the periods derived from the 3 photometric bands ($G$, $G_{\mathrm{BP}}$, and $G_{\mathrm{RP}}$);

4. 4.

   search for secondary periodicities, performed only for sources with $>40$ transits in the $G$ band and with scatter of the best-fit model of the Cepheid $G$-band light curves larger than 0.025 mag.

The following additional steps applied to sources confirmed as Cepheid variables (see figure 3 in Clementini et al. 2019):

1. 1.

   Cepheid multimode search;

2. 2.

   Cepheid type identification;

3. 3.

   type II Cepheid sub-classification in terms of BL Herculis, W Virginis, and RV Tauri classes;

4. 4.

   classical Cepheid mode identification;

5. 5.

   anomalous Cepheid mode identification;

6. 6.

   Cepheid final classification and validation;

7. 7.

   stellar parameters estimate: metallicity for fundamental mode Classical Cepheid variables with period shorter than about 6 days.

A detailed description of each step can be found in Clementini et al. (2016, 2019) and Ripepi et al. (2023).