  The present study collects 456 new times of maximum light of the classical
Cepheid RT Aur, covering the period from 1897 to 2022. The O-C diagram
resulting from these observations shows that the period given by the GCVS has
to be corrected. It results that no strong period variation is found. However,
the observed O-C residuals show a long term periodic trend. In the hypothesis
of RT Aur being in a binary system, an orbit cannot be deduced from the
available astrophysical data.
