The 2pt+: an enhanced 2 point correlation function
  We introduce a new method for testing departure from isotropy of points on a
sphere based on an enhanced form of the two-point correlation function that we
named 2pt+. This method uses information from the two extra variables that
define the vector between two points on a sphere. We show that this is a
powerful method to test departure from isotropy of a distribution of points on
a sphere especially when the number of events is small. We apply the method to
a few examples in astronomy and discuss the relevance for limited datasets,
such as the case of ultra-high energy cosmic rays.
