Full Stokes observations in the He I 1083 nm spectral region covering an M3.2 flare

We present an exceptional data set acquired with the Vacuum Tower Telescope (Tenerife, Spain) covering the pre-flare, flare, and post-flare stages of an M3.2 flare. The full Stokes spectropolarimetric observations were recorded with the Tenerife Infrared Polarimeter in the He I 1083.0 nm spectral region. The object under study was active region NOAA 11748 on 2013 May 17. During the flare the chomospheric He I 1083.0 nm intensity goes strongly into emission. However, the nearby photospheric Si I 1082.7 nm spectral line profile only gets shallower and stays in absorption. Linear polarization (Stokes Q and U) is detected in all lines of the He I triplet during the flare. Moreover, the circular polarization (Stokes V) is dominant during the flare, being the blue component of the He I triplet much stronger than the red component, and both are stronger than the Si I Stokes V profile. The Si I