RMextract

What is RMextract?

RMextract is a set of python based tools that can be used to calculate Ionospheric Faraday Rotation for a given epoch, location and line of sight. Faraday rotation occurs when an electromagnetic wave travels through an ionised plasma in the presence a magnetic field. Since left and right handed circular polarized waves travel at a different speed in such plasma, the net effect is a rotation of the linear polarisation angle, which is proportional to the square of the wavelength of the incoming wave:

The rotation measure RM is:

with n_e the electron density and B|| the parallel magnetic field. In RMextract we do not perform the full integral, but instead assume for the ionosphere an infinite thin layer at a given ionospheric height. In that case the equation becomes:

with vTEC the vertical integrated total electron content and am the geometrically airmass correction factor. In order to get the rotation measure, we need the total electron content and the Earth magnetic field at the piercepoint through the ionospheric screen.

Some documentation about the usage can be found here.