Transformations from WISE to 2MASS, SDSS and BVI Photometric Systems: II. Transformation Equations for Red-Clump Stars

We present colour transformations for the conversion of Wide-Field Survey Explorer W1, W2, and W3 magnitudes to the Johnson-Cousins BVI_c, Sloan Digital Sky Survey gri, and Two Micron All Sky Survey JHK_s photometric systems, for red clump (RC) stars. RC stars were selected from the Third Radial Velocity Experiment Data Release. The apparent magnitudes were collected by matching the coordinates of this sample with different photometric catalogues. The final sample (355 RC stars) was used to obtain metallicity-dependent and free-of-metallicity transformations. These transformations combined with known absolute magnitudes at shorter wavelengths can be used in space density determinations for the Galactic (thin and thick) discs at distances larger than the ones evaluated with JHK_s photometry alone, hence providing a powerful tool in the analysis of Galactic structure.