The GREGOR Fabry-P\'erot Interferometer and its companion the Blue Imaging Solar Spectrometer

摘要

The GREGOR Fabry-P\'erot Interferometer (GFPI) is one of three first-lightinstruments of the German 1.5-meter GREGOR solar telescope at the Observatoriodel Teide, Tenerife, Spain. The GFPI allows fast narrow-band imaging andpost-factum image restoration. The retrieved physical parameters will be afundamental building block for understanding the dynamic Sun and its magneticfield at spatial scales down to about 50 km on the solar surface. The GFPI is atunable dual-etalon system in a collimated mounting. It is designed forspectrometric and spectropolarimetric observations between 530-860 nm and580-660 nm, respectively, and possesses a theoretical spectral resolution R ofabout 250,000. Large-format, high-cadence CCD detectors with sophisticatedcomputer hard- and software enable the scanning of spectral lines in time-spansequivalent to the evolution time of solar features. The field-of-view (FOV) of50" x 38" covers a significant fraction of the typical area of active regionsin the spectroscopic mode. In case of Stokes-vector spectropolarimetry, the FOVreduces to 25" x 38". We present the main characteristics of the GFPI includingadvanced and automated calibration and observing procedures. We discussimprovements in the optical design of the instrument and show firstobservational results. Finally, we lay out first concrete ideas for theintegration of a second FPI, the Blue Imaging Solar Spectrometer (BLISS), whichwill explore the blue spectral region below 530 nm.