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 ^ { \prime } , V , r ^ { \prime } and I _ { C } passbands have been acquired at University College London Observatory ( UCLO ) between May 2017 and September 2018 .
We interrogate the wavelength dependence of the \sim month-long dimming and brightening exhibited by the target star over an 85-day interval , immediately following a days-long \sim 5 per cent drop in brightness on Julian Date ( JD ) 2458203 .
Between JD 2458215–300 we measure brightness variations which correspond to relative extinctions of A _ { B } / A _ { V } = 1.39 \pm 0.27 , A _ { g ^ { \prime } } / A _ { V } = 1.16 \pm 0.11 , A _ { r ^ { \prime } } / A _ { V } = 0.80 \pm 0.25 and A _ { Ic } / A _ { V } = 0.49 \pm 0.19 , from which we infer an Angstrom absorption coefficient of 1.33 \pm 0.43 ( R _ { V } \simeq 3.2 ^ { +2.6 } _ { -1.0 } ) .
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 sub-micron-sized grains .
This implies some common mechanism is responsible for the star ’ s variability over both these short and longer timescales .