interesting point. I can begin looking for transits on the 5:3 resonance. My immediate instinct is that it cannot be transiting given the planet is likely at least Neptune radius and should be sticking out like a sore thumb. I should be able to produce constraints on inclination vs radius for a fixed period which will give you a strong constraint to add in.

According to the best TTV/TDV fit mentioned above, the relative inclination of the two planets in the KOI-872 system must be small. We therefore considered the possibility that the outer planet might be transiting but was somehow overlooked. That turned out not to be the case: no transits of the outer planet were detected.

[**From David N’s email from 1/18/2012:**]{}

The short-period TTVs are sensitive to the Mc/M\* ratio only, so I fit for Mc/M\* and it comes out as $\sim$0.0002. For M\*$=$0.8, this would roughly be a Saturn-mass planet.

It would be nice if transits of the 2nd planet can be ruled out. We could use it to give some lower limit on the perturbing planet’s inclination.

Good news: No interesting secondary maxima of chi2 popped out so far, so the two solutions that I 