docs: def calcTransitDuration(self, circular=False):
          """ Estimation of the primary transit time assuming a circular orbit (see :py:func:`equations.transitDuration`)
          """
  
          try:
              if circular:
                  return eq.transitDurationCircular(self.P, self.star.R, self.R, self.a, self.i)
              else:
                  return eq.TransitDuration(self.P, self.a, self.R, self.star.R, self.i, self.e, self.periastron).Td
          except (ValueError,
                  AttributeError,  # caused by trying to rescale nan i.e. missing i value
                  HierarchyError):  # i.e. planets that dont orbit stars
              return np.nan