  We analyze new and published optical photometric data of FU Orionis, an
eruptive pre-main sequence star. The outburst consists of a 5.5 mag rise at B
with an e-folding timescale of roughly 50 days. The rates of decline at B and V
are identical, 0.015 +- 0.001 mag per yr. Random fluctuations superimposed on
this decline have an amplitude of 0.035 +- 0.005 mag at V and occur on
timescales of 1 day or less. Correlations between V and the color indices U-B,
B-V, and V-R indicate that the variable source has the optical colors of a G0
supergiant. We associate this behavior with small amplitude flickering of the
inner accretion disk.
