The light curve of asteroid 21 Lutetia measured by VIRTIS-M during the Rosetta fly-by

► We obtained a total of 165 spectra in the overall range 0.25-5.1 μm. ► We find that the NIR spectrum of Lutetia on its northern hemisphere is essentially flat and grey. ► We find a marked spectral homogeneity throughout two rotational periods. ► We confirm the absence of OH features at 1.9, 2.7, and 3 μm within the sensitivity of VIRTIS. ► We conclude that the northern hemisphere of Lutetia is not linked to the most primitive meteorites.