“Diameter curve” for the active Centaur P2. The continuous curve corresponds to nucleus diameter obtained with the nucleus magnitude m_nucleus (after the subtraction of coma contamination). The dashed curve is the “upper limit” on the nucleus size, obtained with the total photometry m_TOT. The vertical lines indicate the lower limit of albedo values derived in the class (green line, Duffard et al. 2014) and the value measured for the two “canonical” active Centaurs (blue line) Chiron (Bus et al. 1989) and 29P/Schwassmann-Wachmann (Cruikshank & Brown 1983).