A MONTE CARLO METHOD FOR MAKING THE SDSS u-BAND MAGNITUDE MORE ACCURATE

We develop a new Monte Carlo-based method to convert the Sloan Digital Sky Survey (SDSS) u-band magnitude to the south Galactic Cap of the u-band Sky Survey (SCUSS) u-band magnitude. Due to the increased accuracy of SCUSS u-band measurements, the converted u-band magnitude becomes more accurate compared with the original SDSS u-band magnitude, in particular at the faint end. The average u-magnitude error (for both SDSS and SCUSS) of numerous main-sequence stars with increases as the g-band magnitude becomes fainter. When g = 19.5, the average magnitude error of the SDSS u is 0.11. When g = 20.5, the average SDSS u error rises to 0.22. However, at this magnitude, the average magnitude error of the SCUSS u is just half as much as that of the SDSS u. The SDSS u-band magnitudes of main-sequence stars with and are converted, therefore the maximum average error of the converted u-band magnitudes is 0.11. The potential application of this conversion is to derive a more accurate photometric metallicity calibration from SDSS observations, especially for the more distant stars. Thus, we can explore stellar metallicity distributions either in the Galactic halo or some stream stars.