Residuals of JBE frequency derivatives with respect to a constant braking index law fit with n = 2.5, calculated over the whole JBE interval (from 1988 May through 2015 June 15th). The vertical gray lines denote the occurrence of glitches as reported by Espinoza et al. (2011)² (see Table A.1). Nine arrows delimit chosen episodes and are placed at times when (major) glitches appear to change the braking index. The two dashed vertical lines mark the beginning and the end of the data set. The gray broken line indicates the second derivative of the continuous phase function defined in the text. Points used for the fit with the braking law model ϕ_j(t) are displayed in red and green, while points in black are excluded from the fit, as explained in the text. Some post glitch residuals with the value below −0.5 × 10^-12 s^-2 go beyond the scale and are not shown.