Getting More For Your Money: Identifying and Confirming Long-Period   Planets with Kepler
  Kepler will monitor enough stars that it is likely to detect single transits of planets with periods longer than the mission lifetime. We show that by combining the Kepler photometry of such transits with precise radial velocity (RV) observations taken over ~3 months, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20% (for planets with radii greater than that of Neptune) and the masses to within a factor of 2 (for planet masses m_p > M_Jup). We also explore the effects of eccentricity on our estimates of these uncertainties. 
Jennifer C. Yee and B. Scott Gaudi