calc_theta

acstools.polarization_tools.calc_theta(q, u, detector, pav3)

Calculate the position angle of the electric field vector given Stokes Q and U. For ACS, it is also necessary to supply the position angle of the V3 axis of the telescope (PA_V3 in the primary header) and the name of the ACS detector used.

Parameters:
qfloat

Stokes Q parameter.

ufloat

Stokes U parameter.

detector{‘wfc’, ‘hrc’}

Name of the ACS detector used for the observation. Must be either WFC or HRC.

pav3float or Quantity

Position angle of the V3 axis in units of degrees. Found in ACS primary headers with keyword PA_V3.

Returns:
thetaQuantity

Position angle of the electric field vector in degrees.