I have a time series data. I obtained its power spectra. Now i want to obtain its spectral index of the power spectrum. Please help me

 2007.00137      1.56954  0.00367 (1st column- Time, 2nd- Position, 3rd- sigma)
 2007.00411      1.57119  0.00357
 2007.00685      1.57185  0.00357
 2007.00959      1.56980  0.00354
 2007.01233      1.57311  0.00358
 2007.01507      1.57543  0.00352
 2007.01781      1.57261  0.00389
 2007.02055      1.57557  0.00432
 2007.02329      1.57508  0.00374
 2007.02603      1.57176  0.00379
 2007.02877      1.57425  0.00370
 2007.03150      1.57342  0.00367
 2007.03424      1.57477  0.00367
 2007.03698      1.57507  0.00348