Derived frequencies as a function of time. The data points and symbols are the same as in Figure 5, except that the three points by other investigators having large uncertainty and thus being nonconstraining are excluded here. For a constant torque, one would expect a linear progression of the frequency with time and can more readily estimate when the comet could have stopped rotating. Based on our fit, this could have occurred only 56 days past perihelion, or as early as June 8; however, there is some evidence that the slope was somewhat less steep in the final 2 weeks, implying a later critical date.