-band magnitude of the red clump as a distance indicator

We have investigated how the K-band magnitude of the red clump $[M_K(RC)]$ depends on age and metallicity, using 2MASS infrared data for a sample of 24 open clusters with known distances. We show that a constant value of $M_K(RC)=-1.57 \pm 0.05$ is a reasonable assumption to use in distance determinations for clusters with metallicity between -0.5 and +0.4 dex and age between 108.5 and 109.9 years