Intra-night optical polarization monitoring of blazars

Data published in Polychronakis et al. 2025 from the pilot survey of Black hOle Optical polarization TimE-domain Survey (BOOTES, European Union ERC- 2022-STG - BOOTES - 101076343) that occurred in Skinakas Observatory (Robopol polarimeter) from 2024 to early 2025 (supplemented by observations from the Calar Alto, Perkins, and Sierra Nevada observatories, for the same timeframe). The data set includes all the raw intra-night observations for 20 blazar sources. The data that we publish here are (respective columns): name of the source, julian date, polarization degree (p) and its uncertainty (sigma_p), polarization angle (chi) and its uncertainty (sigma_chi), Stokes q and its uncertainty, Stokes u and its uncertainty.