2019PASP..131h4204H

We present an analysis of the results of long-term, multi-band photometric monitoring of the enigmatic star, KIC 8462852. Observations in the B, g', V, r', and I_C passbands have been acquired at University College London Observatory between 2017 May and 2018 September. We interrogate the wavelength dependence of the ∼month-long dimming and brightening exhibited by the target star over an 85 day interval, immediately following a days-long ∼5% drop in brightness on Julian Date (JD) 2,458,203. Between JD 2,458,215-300 we measure brightness variations which correspond to relative extinctions of A_B/A_V=1.39±0.27, A_g'/A_V = 1.16 ± 0.11, A_r'/A_V = 0.80 ± 0.25 and A_Ic/A_V = 0.49 ± 0.19, from which we infer an Ångstrom absorption coefficient of 1.33 ± 0.43 (R_V≃3.2_–1.0^+2.6). As with the days-long "dips", the wavelength dependence of the longer-term brightness variations must also be associated with extinction arising from a dust distribution containing a substantial fraction of submicron-sized grains. This implies some common mechanism is responsible for the star's variability over both these short and longer timescales.