文摘
We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5a0;×a0;1017a0;eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2 % at 99 % C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.