code: def _polarBreaks(self):
          
  
          if self.orbit_index is None:
              raise ValueError('Orbit properties must be defined at ' +
                               'pysat.Instrument object instantiation.' + 
                               'See Instrument docs.')
          else:
              try:
                  self.sat[self.orbit_index]
              except ValueError:
                  raise ValueError('Provided orbit index does not appear to ' +
                                   'exist in loaded data')
  
          # determine where orbit index goes from positive to negative
          pos = (self.sat[self.orbit_index] >= 0)
          npos = -pos
          change = (pos.values[:-1] & npos.values[1:]) | (npos.values[:-1] &
                                                          pos.values[1:])
  
          ind, = np.where(change)
          ind += 1
  
          ut_diff = Series(self.sat.data.index).diff()
          ut_ind, = np.where(ut_diff / self.orbit_period > 0.95)
  
          if len(ut_ind) > 0:
              ind = np.hstack((ind, ut_ind))
              ind = np.sort(ind)
              ind = np.unique(ind)
              # print 'Time Gap'
  
          # create orbitbreak index, ensure first element is always 0
          if ind[0] != 0:
              ind = np.hstack((np.array([0]), ind))
          # number of orbits
          num_orbits = len(ind)
          # set index of orbit breaks
          self._orbit_breaks = ind
          # set number of orbits for the day
          self.num = num_orbits
docs: Determine where breaks in a polar orbiting satellite orbit occur.
  
          Looks for sign changes in latitude (magnetic or geographic) as well as 
          breaks in UT.