def METHOD_NAME(self):
    """dM/dPB this could be a generic function"""
    PB = self.PB.to("second")
    PBDOT = self.PBDOT
    XPBDOT = self.XPBDOT
    return (
        2
        * np.pi
        * u.rad
        * ((PBDOT + XPBDOT) * self.tt0**2 / PB**3 - self.tt0 / PB**2)
    )