We report the results of our optical ( VRI ) photometric observations of the TeV blazar 1ES 0806 + 524 on 153 nights during 2011–2019 using seven optical telescopes in Europe and Asia .
We investigated the variability of the blazar on intraday as well as on long-term timescales .
We examined eighteen intraday light curves for flux and color variations using the most reliable power-enhanced F -test and the nested ANOVA test .
Only on one night was a small , but significant , variation found , in both V band and R band light curves .
The V - R color index was constant on every one of those nights .
Flux density changes of around 80 % were seen over the course of these eight years in multiple bands .
We found a weighted mean optical spectral index of 0.639 \pm 0.002 during our monitoring period by fitting a power law ( F _ { \nu } \propto \nu ^ { - \alpha } ) in 23 optical ( VRI ) spectral energy distributions of 1ES 0806 + 524 .
We discuss different possible mechanisms responsible for blazar variability on diverse timescales .