Program: GS-2019A-Q-222

The NASA K2 mission has been in operation for over four years and has already observed more stars than the original Kepler mission. There are currently over 250 validated K2 exoplanets and more than 500 additional candidates (as of Sept. 2018), up through Campaign 16. TESS has just started science operations, but already has >70 "alerts" (bright, high likelihood exoplanet transit host stars) and will have full candidate lists ready to go in semester 2019A. Many of the confirmed K2 planets and the upcoming K2 & TESS candidates are small (rocky) exoplanets, orbit bright stars, and are amenable to RV mass determination. Our team has shown, and it is now well accepted, that about one half of all exoplanet host stars are binary or multiple systems. Without high resolution images of the host star a) small planets, especially those in habitable zone orbits, can not be validated, and b) any true exoplanet will have, on average, an incorrect radius by a factor of 1.5, that is, the planet will be larger than assumed. This proposal will obtain high resolution imaging for K2 and TESS exoplanet candidate host stars, including those thought to harbor small, habitable zone planets to provide validation and assess binarity. We will continue to make all of our reduced data immediately public at the NASA Exoplanet Archive.