Studies of clustering in the arrival directions of cosmic rays detected at the Pierre Auger Observatory above 10 EeV

If clustering of the arrival directions of ultra high energy cosmic rays is discovered, this would provide important information about their origin, composition, and the galactic and extragalactic magnetic fields. We present here the analysis of the autocorrelation function of the data from the Pierre Auger Observatory as a function of the angular scale and the energy threshold. We compare our results with the signals found by previous experiments.