A plot showing the probability of all outbursts being un-detected by the Harvard plate archives as a function of the recurrence time scale of KT Eri. For example, for a recurrence time scale of 10 years at least one outburst would have been visible in the Harvard data. However, for recurrence times  > 120.5 years all outbursts would go undetected as this is the limit of the data span. If the recurrence time of the system is 41 years then the probability that no outburst was caught by the Harvard data is only 15%.