Erratum: The elliptical power law profile lens (Astronomy and Astrophysics (2015) 580 (A79) DOI: 10.1051/0004-6361/201526773)

The authors would like to point out two errors in the article as it was originally published. Due to a typographical error, Eq. (17) erroneously expresses the shear of the elliptical power law profile lens in the elliptic coordinates R and ' instead of the physical polar coordinates r and ø. The correct expression is (r; ø) = -ei2ø κ (r) + (1 - t) ei ø α (r; ø) r ; (17) i.e. the same formula with the substitutions R → r and α → ø. This result correctly recovers the singular isothermal ellipsoid result γ = -κ (z/z∗) = -ei2ø when t = 1. The preceding Eq. (16) is correct. Furthermore, Fig. 2 incorrectly contains and refers to the pseudo-caustics for power law profile lenses with slope t > 1. Since the main result of the original paper shows that the elliptical lenses have the same (elliptical) radial profile as the circular ones, the degenerate critical line at the origin R = 0 is mapped to R = 1 when t > 1, just as in the circular case. Hence only the isothermal case t = 1 has a pseudo-caustic at finite radius. The dashed lines in the plot are due to a numerical error. A corrected version of Fig. 2 is shown below. (Figure Presented).