First SPINOR inversion of data from the Fast Solar Polarimeter

The Fast Solar Polarimeter (FSP) is a novel instrument developed by MPS in collaboration with the MPG semiconductor lab. The focus of FSP is on increased polarimetric sensitivity in combination with highest spatio-temporal resolution. It is based on a fast and low-noise pnCCD camera allowing for full-Stokes polarization modulation at 100 Hz which sufficiently suppresses spurious signals from disturbances like atmospheric seeing. In addition the high frame rate allows for post-facto image restorations at a cadence of order 1s, i.e. well below the solar evolution timescale.

An FSP prototype has been tested at the TESOS filtergraph instrument of the German Vacuum Tower Telescope on Tenerife. The Figure shows a snapshot of a time series covering a small active region, which has been inverted with the SPINOR code. The Fe I line at 630.25 nm has been repetitively scanned with 5 spectral positions to obtain a spectro-polarimetric time series with a cadence of 16s and with a polarimetric sensitivity of order 0.5%. Each snapshot of the time series is the result of a MOMFBD restoration based on some 600 individual frames covering about 1.9s of observing time. This demonstration result represents an important milestone in the FSP project. For the time being a science-ready version of FSP is developed based on a larger 1kx1k pnCCD camera and a dual-beam configuration.