Spin frequency evolution folded with a period of 7746 d and centered on most recent measurements. The most recent measurements have been shifted for a better comparison, with the same spin frequency scale. Black empty circles, filled gray squares and filled gray inverted triangles correspond to the most recent Fermi/GBM measurements and BATSE and RXTE/ASM measurements from Wilson et al. (2005), respectively. The vertical dotted line indicates the time of the OPJ95 and of the predicted orbital phase shift.