The STIX Aspect System (SAS): The Optical Aspect System of the Spectrometer/Telescope for Imaging X-Rays (STIX) on Solar Orbiter

• DOI: 10.1007/s11207-020-01660-w
• Publication Date: 2020-07-03T12:02:36Z
• Authors: A. Warmuth; H. Önel; G. Mann; J. Rendtel; K. G. Strassmeier; C. Denker; G. J. Hurford; S. Krucker; J. Anderson; S.-M. Bauer; W. Bittner; F. Dionies; J. Paschke; D. Plüschke; D. P. Sablowski; F. Schuller; V. Senthamizh Pavai; M. Woche; D. Casadei; S. Kögl; N. G. Arnold; H.-P. Gröbelbauer; D. Schori; H. J. Wiehl; A. Csillaghy; O. Grimm; P. Orleanski; K. R. Skup; W. Bujwan; K. Rutkowski; K. Ber
• Keywords: Orbiter; Optical telescope; Solar telescope; Imaging spectrometer

The Spectrometer/Telescope for Imaging X-rays (STIX) is a remote sensing instrument on Solar Orbiter that observes the hard X-ray bremsstrahlung emission of solar flares. This paper describes STIX Aspect System (SAS), subunit measures pointing relative to Sun with precision $\pm 4''$ , which required accurately localize reconstructed images Sun. operating principle SAS based an optical lens onto plate perforated by small apertures arranged in cross-shaped configuration four radial arms. light passing through each arm detected photodiode. Variations spacecraft and distance from cause image move over different apertures, leading modulation measured lightcurves. These signals are used ground analysis calculate locations limb, hence telescope.