Top to bottom: Evolution of the observed spin frequency (f), its first derivative (ḟ), and its second derivative ($\ddot{f}$) as a function of time (MJD). The vertical yellow and green lines indicate Epochs 1 and 2 respectively. The values from R19 are shown in red, and the results from this work are shown in blue. The large change in the ḟ value between the two epochs can be clearly seen.