Radial velocity & photometry of HD106315 & GJ9827

We refined the planets ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multiyear high-cadence observing campaign with Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder Spectrograph, we improved the planets mass measurements in anticipation of Hubble Space Telescope transmission spectroscopy.

For GJ9827, we modeled activity-induced radial velocity signals with a Gaussian process informed by the CalciumII H&K lines in order to more accurately model the effect of stellar noise on our data. We measured planet masses of Mb=4.87{+/-}0.37M{Earth}, Mc=1.92{+/-}0.49M{Earth}, and Md=3.42{+/-}0.62M{Earth}. For HD 06315, we found that such activity radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well (Teff>6200K).