docs: def RV_timeseries(self,ts,recalc=False):
          """
          Radial Velocity time series for star 1 at given times ts.
  
          :param ts:
              Times.  If not ``Quantity``, assumed to be in days.
          :type ts:
              array-like or ``Quantity``
  
          :param recalc: (optional)
              If ``False``, then if called with the exact same ``ts``
              as last call, it will return cached calculation.
  
          """
          if type(ts) != Quantity:
              ts *= u.day
  
          if not recalc and hasattr(self,'RV_measurements'):
              if (ts == self.ts).all():
                  return self._RV_measurements
              else:
                  pass
  
          RVs = Quantity(np.zeros((len(ts),self.N)),unit='km/s')
          for i,t in enumerate(ts):
              RVs[i,:] = self.dRV(t,com=True)
          self._RV_measurements = RVs
          self.ts = ts
          return RVs