Calculate the 2D integral of the 1D surface brightness profile 
        (i.e, the flux) between rmin and rmax (elliptical radii). 

        Parameters:
        -----------
        rmin : minimum integration radius (deg)
        rmax : maximum integration radius (deg)

        Returns:
        --------
        integral : Solid angle integral (deg^2)

def integrate(self, rmin=0, rmax=np.inf):
        """
        Calculate the 2D integral of the 1D surface brightness profile 
        (i.e, the flux) between rmin and rmax (elliptical radii). 

        Parameters:
        -----------
        rmin : minimum integration radius (deg)
        rmax : maximum integration radius (deg)

        Returns:
        --------
        integral : Solid angle integral (deg^2)
        """
        if rmin < 0: raise Exception('rmin must be >= 0')
        integrand = lambda r: self._pdf(r) * 2*np.pi * r
        return scipy.integrate.quad(integrand,rmin,rmax,full_output=True,epsabs=0)[0]