  The 1703 was the first year of full operation of the meridian line in the
Basilica of St. Maria degli Angeli in Rome. The instants of solstices and
equinoxes, the \textit{Anni Cardines}, obtained by comparing transit timings of
Sun and Sirius, also in daytime, are affected either by the East deviation of
the meridian line of about 5' Eastward (geometrical effect), either by the
stellar aberration of Sirius (relativistic effect). Similarly the seasonal
shifts of Sirius' declination observed by Bianchini are here firstly recognized
as depending on the stellar aberration in ecliptic latitude. The eccentricity
of the Earth's orbit and the orientation of its axis in the space can be
measured, since Ptolemy, by knowing the exact timing of the solstices and the
equinoxes. The dates of 1703 equinoxes and solstices have been published by
Francesco Bianchini in local roman mean time, referred to the local (roman)
mean noon, i.e. after the solar meridian mean transit time. By using the
observations of the three lunar eclipses of 1703 we found the equation of time
for that year, and the UTC corresponding timings of the beginning of the
seasons. This operation lead to find the contribution of the Sirius aberration
to the instant calculated by Bianchini with respect to the current celestial
mechanical models of IMCCE.

History and Philosophy of Physics;Solar and Stellar Astrophysics