Hidden power of near-infrared data for the study of young clusters:
  Illustrative case of RCW 38
  Studies of star formation rely heavily on observations in the near-infrared,
but they typically need information from other wavelengths for interpretation.
We show that we can infer distances and estimate the membership of young
stellar objects for young clusters independently using (ground-based)
near-infrared, $J$, $H,$ and $K_S$ broadband data alone. We also show that we
can estimate a lower limit for the fraction of sources with $2.2~\mu$m excess
emission with a sensitivity comparable to that of mid-infrared space data, but
with better resolution and fewer biases. Finally, we show that the typical
methods for inferring masses from these data may produce substantially
unreliable results. This method is applied to the young, massive cluster RCW
38, for which we estimate a distance of 1.5 kpc and a $K_S$-band excess
fraction larger than 60\%.
