Swift light curves of Mkn 841: a) in August 2008 and b) in 2007–2008: XRT count rates (in c s^-1, open circles) and UVOT fluxes (filled circles) obtained with an arbitrary magnitude-to-flux conversion coefficient from the V-band magnitudes. The errors are statistical only and correspond to 1-σ. The data points in b) are from Grupe et al. (2010), except the last XRT and UVOT ones, which correspond to the averages of the August 2008 points for the two instruments shown in a). The zero time in b) corresponds to 2007 January 1, 00 UT.