A microlensing event has been recently used for high-precision, multicolour measuring a limb darkening profile on the surface of a K3 giant and revealed a significant disagreement between the observed and predicted from atmospheric models disk brightness distribution (Fields et al., 2003). The Optical Gravitational Lensing Experiment (OGLE) survey of bulge giants provided photometric evidence for stellar spots via microlensing events (Udalski et al., 1995). Modelling of the spots on the stars selected from the OGLE database was undertaken by Guinan et al. (1997). Further theoretical investigation of possible detections of stellar spots by gravitational microlensing was carried out by Heyrovský and Sasselov (2000) and Hendry et al. (2002). They concluded that starspots generally produce a clear signature only for transit events. Moreover, this signature is strongly suppressed by limb darkening for spots close to the limb, although spots may still be clearly detected for favourable lens trajectories. It was found also that in order for microlensing events to be an effective starspot imaging tool, intensive temporal sampling throughout the transit is needed.
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