We present a new tool for studying the spectral energy distributions (SEDs) and color-magnitude diagrams (CMDs) of galaxies and star clusters, BINARY STAR TO FIT (BS2fit). A key feature of this tool is that it takes the eects of binaries, stellar rotation and star formation history into account. It can be used to determine many parameters, including distance, extinction, binary fraction, rotational star fraction, and star formation history. Because more factors are included than in previous tools, BS2fit can potentially give new insight into the properties of galaxies and clusters. One can contact the authors for cooperation and helps via.

ABSTRACT
1. IMPORTANCE OF SPECTRAL AND CMD STUDIESOF GALAXIES AND STAR CLUSTERS
2. NEW TOOL FOR SPECTRAL AND CMD STUDIES
    2.1. Basis of BS2fit
    2.2. BS2fit for CMD
    2.3. BS2fit for SED
3. CONCLUSION
REFERENCES

• Zhongmu Li(Dali University)
• Caiyan Mao(Dali University)