Reduction of polarimetric data using Mueller calculus applied to Nasmyth instruments

We present a method based on Mueller calculus to calibrate linear polarimetric observations. The key advantages of the proposed way of calibration are: (1) that it can be implemented in a data reduction pipeline, (2) that it is possible to do accurate polarimetry also for telescopes/instruments with polarimetric non-friendly architecture (e.g. Nasmyth instruments) and (3) that the proposed strategy is much less time consuming than standard calibration procedures. The telescope/instrument will polarimetrically be described by a train of Mueller matrices. The components of these matrices are dependent on wavelength, incident angle of the incoming light and surface properties. The result is, that an observer gets the polarimetrically calibrated data from a reduction pipeline. The data will be corrected for the telescope/instrumental polarisation off-set and with the position angle of polarisation rotated into sky coordinates. Up to now these two calibration steps were mostly performed with the help of dedicated and time consuming night-time calibration measurements of polarisation standard stars.