The IMaX polarimeter for the solar telescope SUNRISE of the NASA long duration balloon program

¹ Insitituto Nacional de Técnica Aeroespacial-INTA, Torrejón de Ardoz, 28850 Madrid, Spain.
² Instituto de Astrofísica de Canarias-IAC. La Laguna, 38200 Tenerife, Spain.
³ Instituto de Astrofísica de Andalucía-IAA (CSIC). P.O. Box 3004, 18080 Granada, Spain.
⁴ Grupo de Astronomía y Ciencias del Espacio-GACE (UV). Paterna, 46980 Valencia, Spain.

Abstract

On June 8th 2009 the SUNRISE mission was successfully launched. This mission consisted of a 1m aperture solar telescope on board of a stratospheric balloon within the Long Duration Balloon NASA program. The flight followed the foreseen circumpolar trajectory over the Artic and the duration was 5 days and 17 hours. One of the two postfocal instruments onboard was IMaX, the Imaging Magnetograph eXperiment. This instrument is a solar magnetograph which is a diffraction limited imager capable to resolve 100 km on the solar surface, and simultaneously a high sensitivity polarimeter (<10^-3) and a high resolution spectrograph (bandwidth <70mÅ). The magnetic vectorial map can be extracted thanks to the well-know Zeeman effect, which takes place in the solar atoms, allowing to relate polarization and spectral measurements to magnetic fields. The technological challenge of the IMaX development has a special relevance due to the utilization of innovative technologies in the Aeroespacial field and it is an important precedent for future space missions such as Solar Orbiter from ESA. Among these novel technologies the utilization of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators and a LiNbO₃ etalon as tunable spectral filter are remarkable. Currently the data obtained is being analyzed and the preliminary results show unprecedented information about the solar dynamics.