CONICET | Buscador de Institutos y Recursos Humanos

We present a comprehensive study of the inﬂuence of the geomagnetic ﬁeld on the energy estimation of extensive air showers with a zenith angle smaller than 60º, detected at the Pierre Auger Observatory. The geomagnetic ﬁeld induces an azimuthal modulation of the estimated energy of cosmic rays up to the ∼ 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the eﬀect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic eﬀect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for.