Synthetic lightcurves obtained with the KOALA model (solid line) plotted against the 50 lightcurves (with points represented by filled dots) used in the current study, plotted in arbitrary relative intensity. The observing conditions (phase angle α, average apparent visual magnitude m_V, number of points and duration of the observation) of each lightcurve are reported on each panel, along with the synthetic lightcurve fit RMS (in percent and visual magnitude). Lightcurve observations were acquired by (1 − 3) Chang & Chang (1963) (4 − 9) Lupishko et al. (1983), (10 − 11) Zappala et al. (1984), (12) Lupishko et al. (1983), (13) Zappala et al. (1984), (14 − 15) Lupishko et al. (1987), (16) Dotto et al. (1992), (17 − 21) Lupishko & Velichko (1987), (22) Lagerkvist et al. (1995), (23) Lupishko & Velichko (1987), (24) Lagerkvist et al. (1995), (25 − 28) Denchev et al. (1998), (29 − 32) Denchev (2000) (33 − 36) L. Bernasconi, (37) R. Roy, (38) Carvano et al. (2008), (39 − 40) Nedelcu et al. (2007), (41) OSIRIS on Rosetta (Faury et al. 2009), (42) Belskaya et al. (2010), (43 − 46) F. Colas, F. Vachier, A. Kryszczynska and M. Polinska, (47) R. Poncy, (48 − 49) R. Naves, (50) P. Wiggins.