2020, Solanki, S.K., del Toro Iniesta, J.C., Woch, J., Gandorfer, A., Hirzberger, J., Alvarez-Herrero, A., Appourchaux, T., Martínez Pillet, V., Pérez-Grande, I., Sanchis Kilders, E., Schmidt, W., Garranzo-García, D., Laguna, H., Martín, J.A., Navarro, R., Villanueva, J., Núñez Peral, A., Royo, M., Sánchez, A., Silva-López, M., Fourmond, J.-J., Berkefeld, Th., Ruiz de Galarreta, C., Bouzit, M., Hervier, V., Le Clec'h, J.C., Szwec, N., Chaigneau, M., Buttice, V., Volkmer, R., Dominguez-Tagle, C., Philippon, A., Baumgartner, J., Boumier, P., Le Cocguen, R., Baranjuk, G., Bell, A., Heidecke, F., Maue, T., Blanco Rodríguez, J., Nakai, E., Scheiffelen, T., Sigwarth, M., Soltau, D., Domingo, V., Fiethe, B., Ferreres Sabater, A., Gasent Blesa, J.L., Rodríguez Martínez, P., Osorno Caudel, D., Bosch, J., Casas, A., Carmona, M., Gómez Cama, J.M., Herms, A., Roma, D., Guan, Y., Alonso, G., Gómez-Sanjuan, A., Piqueras, J., Torralbo, I., Lange, T., Michel, H., Michalik, H., Bonet, J.A., Fahmy, S., Müller, D., Zouganelis, I., Deutsch, W., Busse, D., Fernandez-Rico, G., Grauf, B., Gizon, L., Heerlein, K., Kolleck, M., Lagg, A., Meller, R., Müller, R., Schühle, U., Staub, J., Enge, R., Albert, K., Alvarez Copano, M., Beckmann, U., Bischoff, J., Frahm, S., Germerott, D., Guerrero, L., Löptien, B., Meierdierks, T., Oberdorfer, D., Papagiannaki, I., Ramanath, S., Bellot Rubio, L.R., Schou, J., Werner, S., Yang, D., Zerr, A., Bergmann, M., Bochmann, J., Heinrichs, J., Meyer, S., Monecke, M., Müller, M.-F., Cobos Carracosa, J.P., Sperling, M., Álvarez García, D., Aparicio, B., Balaguer Jiménez, M., Girela, F., Hernández Expósito, D., Herranz, M., Labrousse, P., López Jiménez, A., Orozco Suárez, D., Ramos, J.L., Barandiarán, J., Vera, I., Bastide, L., Campuzano, C., Cebollero, M., Dávila, B., Fernández-Medina, A., García Parejo, P.

This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from outside the Sun-Earth line. It is the key instrument meant to address the top-level science question: How does the solar dynamo work and drive connections between the Sun and the heliosphere? SO/PHI will also play an important role in answering the other top-level science questions of Solar Orbiter, as well as hosting the potential of a rich return in further science. SO/PHI measures the Zeeman effect and the Doppler shift in the FeI 617.3nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO_3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders (LCVRs). The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2kx2k CMOS detector. To save valuable telemetry, the raw data are reduced on board, including being inverted under the assumption of a Milne-Eddington atmosphere, although simpler reduction methods are also available on board. SO/PHI is composed of two telescopes; one, the Full Disc Telescope (FDT), covers the full solar disc at all phases of the orbit, while the other, the High Resolution Telescope (HRT), can resolve structures as small as 200km on the Sun at closest perihelion. The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line.

2010, Berkefeld, T., Schmidt, W., Soltau, D., Bell, A., Doerr, H.P., Feger, B., Friedlein, R., Gerber, K., Heidecke, F., Kentischer, T., von der Lühe, O., Sigwarth, M., Wälde, E., Barthol, P., Deutsch, W., Gandorfer, A., Germerott, D., Grauf, B., Meller, R., Álvarez-Herrero, A., Knölker, M., Pillet, V.M., Solanki, S.K., Title, A.M.

This paper describes the wave-front correction system developed for the Sunrise balloon telescope, and it provides information about its in-flight performance. For the correction of low-order aberrations, a Correlating Wave-Front Sensor (CWS) was used. It consisted of a six-element Shack - Hartmann wave-front sensor (WFS), a fast tip-tilt mirror for the compensation of image motion, and an active telescope secondary mirror for focus correction. The CWS delivered a stabilized image with a precision of 0.04 arcsec (rms), whenever the coarse pointing was better than ± 45 arcsec peak-to-peak. The automatic focus adjustment maintained a focus stability of 0.01 waves in the focal plane of the CWS. During the 5.5 day flight, good image quality and stability were achieved during 33 hours, containing 45 sequences, which lasted between 10 and 45 min. © 2010 The Author(s).