ring_r_out

gammapy.background.ring_r_out(theta, r_in, area_factor)

Compute ring outer radius.

The determining equation is:

area_factor = off_area / on_area = (pi (r_out**2 - r_in**2)) / (pi * theta**2 )

Parameters:

theta : float

On region radius

r_in : float

Inner ring radius

area_factor : float

Desired off / on area ratio

Returns:

r_out : float

Outer ring radius