compute_fvar¶
-
gammapy.time.
compute_fvar
(flux, flux_err)[source]¶ Calculate the fractional excess variance.
This method accesses the the
FLUX
andFLUX_ERR
columns from the lightcurve data.The fractional excess variance \(F_{var}\), an intrinsic variability estimator, is given by
\[F_{var} = \sqrt{\frac{S^{2} - \bar{\sigma^{2}}}{\bar{x}^{2}}}.\]It is the excess variance after accounting for the measurement errors on the light curve \(\sigma\). \(S\) is the variance.
- Parameters
- Returns
- fvar, fvar_err
ndarray
Fractional excess variance.
- fvar, fvar_err
References
- Vaughan2003
“On characterizing the variability properties of X-ray light curves from active galaxies”, Vaughan et al. (2003) https://ui.adsabs.harvard.edu/abs/2003MNRAS.345.1271V