Constraints on the mass of the secondary star in GJ 3626 as a function of the apparent angular separation of the two components. The red dotted and blue dashed lines represent the contrast curves of the Robo-AO and FastCam observations, respectively. The green solid line indicates the minimum mass limit computed from RVs. The solid and dot-dashed lines, and the dashed and dotted lines are constraints from RVs on the angular separation at the time of the FastCam and Robo-AO observations, respectively, for orbital inclinations between 0 and 90 deg. The shaded regions indicate mass values that are not compatible with the observations.