α factors for MetOp-02 with 12 months in-between, calculated as described in Section 5.3. The 0° detector is shown as open triangles, and the 90° as filled triangles. The estimated error is calculated based on the 95% prediction interval. Factors from Sandanger et al. (2015) are shown as open (0°) and filled (90°) blue circles. Monthly α factors calculated with their method for E > 90 keV are displayed as blue solid (0°) and dashed (90°) lines.