Polarized light provides key information on the physical conditions and geometry of astrophysical plasmas otherwise unattainable via conventional spectroscopy. In particular, the remote sensing of solar and stellar magnetic fields requires the measurement and rigorous theoretical interpretation of polarization signals in atomic and molecular lines

One of the calibration problems posed by the new generation of mid-infrared instrumentation on 8--10~m class telescopes is that of polarimetric calibration. To be able to calibrate polarimetric data reliably it is necessary to be able to measure both the instrumental polarization and the efficiency of detection of polarization with a high degree of

We present a study over three single-site campaigns to investigate the photometric behaviour of the PNN NGC 246. We observed this object in 2000 and 2001. The analysis of the light curves indicates complex and variable temporal spectra. Using wavelet analysis we have found evidences for changes on time scales of hours in the 2000 dataset. The

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Phase diversity techniques actually provide robust post-processing methods to restore solar images degraded by seeing-optical aberrations. We present preliminary results of the application of a Partitioned Phase-Diverse Speckle (PPDS) technique at THEMIS. The images have been acquired using the IPM broad-band CCD camera and reduced using a suitable

The Multi-site Spectroscopic Telescope is a virtual instrument and the name of a collaboration that opens up a new observational window by combining continuous observations of spectroscopic variations and simultaneous photometric monitoring. This constitutes an enormous observational effort, but in return promises to finally provide access to a