Skip to main content

To find and download HEASARC data in the cloud, you can use astroquery.heasarc or download our new tool, hark.

The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.


polpow: Power-law dependent polarization

This multiplicative model applies a polarization with a power-law dependence on energy. The factor applied depends on which Stokes parameter the spectrum is for. The Stokes parameter is determined using an XFLTnnnn keyword with values “Stokes:0”, “Stokes:1”, or “Stokes:2”, for I, Q, U, respectively.

The fraction and angle are determined by

$\displaystyle A(E) = {\tt Anorm} \times E^{-{\tt Aindex}}$
$\displaystyle \psi(E) = {\tt psinorm} \times E^{-{\tt psiindex}}$

The parameters are :

par1 Anorm, the polarization fraction at 1 keV
par2 Aindex, the polarization fraction index
par3 psinorm, the polarization angle at 1 keV (degrees)
par4 psiindex, the polarization angle index