docs: def rsky_distribution(self,rmax=None,smooth=0.1,nbins=100):
          """
          Distribution of projected separations
  
          Returns a :class:`simpledists.Hist_Distribution` object.
  
          :param rmax: (optional)
              Maximum radius to calculate distribution.
  
          :param dr: (optional)
              Bin width for histogram
  
          :param smooth: (optional)
              Smoothing parameter for :class:`simpledists.Hist_Distribution`
  
          :param nbins: (optional)
              Number of bins for histogram
  
          :return:
              :class:`simpledists.Hist_Distribution` describing Rsky distribution
  
          """
          if rmax is None:
              if hasattr(self,'maxrad'):
                  rmax = self.maxrad
              else:
                  rmax = np.percentile(self.Rsky,99)
          dist = dists.Hist_Distribution(self.Rsky.value,bins=nbins,maxval=rmax,smooth=smooth)
          return dist