Detection limit curves in black for two targets in the BEBOP programme: J0035-69(left panel) and J0310-31 (right panel). Each curve represents the smallest m_c sin I_c for a putative circumbinary planet at a given period, according to the periodogram measure of detectability described in Sect. 8.2. For each target there are 20 black curves, one for each of the tested orbital phases of the injected planet. At seven discrete periods a series of tests were run to recover n-body simulated circumbinary planets with the YORBIT genetic algorithm. At these periods a green circle indicates a successful recovery, whereas a red diamond indicates a failure.