def Keck_distortion(measured_wave, cutoff=10000.):
    """Telescope dependent distortion function for the Keck sample."""
    slope1 = .0600
    intercept1 = -100
    slope2 = .160
    intercept2 = -1500
    if measured_wave < cutoff:
        return measured_wave * slope1 + intercept1
    else:
        return measured_wave * slope2 + intercept2