KH photometry of Orion Nebula Cluster

At the age and distance of this cluster, and in the absence of extinction, the hydrogen-burning limit (0.08M_{sun}_) occurs at K~13.5mag, while an object of mass 0.02M_{sun}_ has K~16.2mag. Our photometry is complete for source detection at the 7{sigma} level to K~17.5mag and thus is sensitive to objects as low-mass as 0.02M_{sun}_ seen through visual extinction values as high as 10mag.

We use the observed magnitudes, colors, and star counts to constrain the shape of the inner ONC stellar mass function across the hydrogen-burning limit. After determining the stellar age and near-infrared excess properties of the optically visible stars in this same inner ONC region, we present a new technique that incorporates these distributions when extracting the mass function from the observed density of stars in the K-(H-K) diagram.