Top: the normalized nightly Cousins R band photometric data set for WASP-103, acquired with the C14 automated imaging telescope at Fairborn Observatory. Vertical dashed lines denote separate observing seasons. Gaps are due to target visibility and the Arizona monsoon season (July–September). Middle: the frequency spectrum of the normalized data set suggests low-amplitude variability with a period of 6.814 days. Bottom: the normalized data set phased to the 6.814 day period, which we interpret as rotational modulation of a star spot or spots. A least-squares sine fit to the 6.814 day rotation period gives a peak-to-peak amplitude of just 0.005 mag.