Polarimetric studies of stars, supernovae, clusters and galaxies are able to provide crucial information about the intrinsic properties of these objects. Polarimetry is also extremely important to understand the properties of the dust that might affect the observations and lead to systematic effects.
In our work we investigate the instrumental polarization in FORS2- the FOcal Reducer and low dispersion Spectrograph at Very Large Telescope, ESO. With optical multiband sky observations in BVRI during full moon we were able to produced 2D maps of the the instrumental polarization.
These maps are particularly relevant in polarimetric studies of extended sources.
This work was supported by FCT- Fundacao para a Ciencia e Tecnologia and by Project PTDC/FIS-AST-31546