The SOS Cep&RRL processing uses tools such as: period-amplitude () and
period-luminosity () relations in the -band, as described in the documentation
for the processing of RR Lyrae and Cepheid
stars released in Gaia Data Release 1, (Clementini et al.2016).
For the Gaia Data Release 2 data processing (Clementini et al.2018)
we also use tools based on the and photometry,
such as the period-luminosity in the RP-band and the period-Wesenheit
() relation in , . Furthermore, we implemented i) use of parallaxes
according to the Astrometric Based Luminosity formulation, (i.e. working directly in
parallax space; see, e.g., (Gaia Collaboration et al.2017) and references therein)
and applying different , relations depending on source position on sky
(whether in the Large Magellanic Cloud, in the Small Magellanic Cloud or outside
them); ii) calculation of metallicity ([Fe/H]) for the RR Lyrae stars and for Cepheid variables with period shorter than about 6 days from the Fourier parameters and,
iii) calculation of interstellar absorption in the -band for the RRab stars
from a relation based on -band peak-to-peak amplitude and period.