The SUNRISE UV Spectropolarimeter and imager for SUNRISE III

FELLER, ALEX; GANDORFER, ALEX; IGLESIAS, FRANCISCO A.; LAGG, ANDREAS; RIETMULLER, TINO; SOLANKI, SAMI K.

Conferencia; Ground-based and Airborne Instrumentation for Astronomy VIII; 2020

SPIE

Sunrise is a balloon-borne solar observatory dedicated to the investigation of key processes of the magneticeld and the plasma ows in the lower solar atmosphere. The observatory operates in the stratosphere at analtitude of around 37 km in order to avoid image degradation due to turbulence in the Earth´s atmosphere and toaccess the UV range. The third science ight of Sunrise will carry new instrumentation which samples the solarspectrum over a broad wavelength domain from the UV to the near IR and covers an extended height range in thesolar atmosphere. A key feature of the Sunrise UV Spectropolarimeter and Imager (SUSI) operating between309 nm and 417 nm, is its capability to simultaneously record a large number of spectral lines. By combining thespectral and polarization information of many individual lines with dierent formation heights and sensitivities,the accuracy and the height resolution of the inferred atmospheric parameters can be signicantly increased.The spectral bands of SUSI are selected one at a time by rotating a diraction grating with respect to axed polarimetry unit. The spatial and spectral eld of view on the 2k x 2k cameras is 59 arcsec and 2.0 -2.3 nm, respectively. A further innovation is the numerical restoration of the spectrograph scans by means ofsynchronized 2D context imaging, a technique that has recently produced impressive results at ground-basedsolar observatories.