Sensitive imaging X-ray observations of young stellar clusters ( YSCs , ages \leq 10 Myr ) are valuable tools for the acquisition of an unbiased census of cluster members needed for Initial Mass Function ( IMF ) studies .
Several dozen YSCs , both nearby and across the Galactic disk , have been observed with the Chandra and XMM-Newton satellites , detecting > 10 , 000 low-mass cluster members .
Many of these samples should be nearly complete down to \simeq 1 M _ { \odot } .
An important additional benefit is that the YSC X-ray luminosity function appears to be universal with a lognormal shape , providing a new standard candle for measurement of YSC distances .