The multi-wavelength correlations and the evolution of spectral index on the quasar 3C 273

The observed data from 2 keV to 5 GHz were complied to investigate possible correlations between different frequency variations by means of discrete correlation function (DCF) analysis. The results show that there are significant flux correlations between different radio bands and the weak correlations between radio and optical variability. The variations of higher frequency components would lead those of lower frequency components. Due to the sparse and uneven data in the X-ray band, the correlations between X-ray and the lower energy bands (radio and optical) cannot be confirmed. In addition, we give the spectral index evolution in each energy band and find out that there are strong anti-correlation between spectral index and flux, in the sense that the spectral index decreases with the flux increases.