Search for Small-Scale Anisotropy of Cosmic Rays above 10^19 eV with   HiRes Stereo
  We present the results of a search for small-scale anisotropy in the distribution of arrival directions of cosmic rays above 10^19 eV measured in stereo by the High Resolution Fly's Eye (HiRes) experiment. Performing an autocorrelation scan in energy and angular separation, we find that the strongest correlation signal in the HiRes stereo data set recorded between December 1999 and January 2004 is consistent with the null hypothesis of isotropically distributed arrival directions. These results are compared to previous claims of significant small-scale clustering in the AGASA data set. 
Stefan Westerhoff (for the High Resolution Fly's Eye Collaboration,   HiRes)