Optical telescope

Abstract: The Solar Optical Telescope (SOT) aboard the Hinode satellite (formerly called Solar-B) consists of the Optical Telescope Assembly (OTA) and the Focal Plane Package (FPP). The OTA is a 50 cm diffraction-limited Gregorian telescope, and the FPP includes the narrow-band (NFI) and wide-band (BFI) filtergraphs, plus the Stokes spectro-polarimeter (SP). SOT provides unprecedented high resolution photometric and vector magnetic images of the photosphere and chromosphere with a very stable point spread function, and is equipped with an image stabilization system that reduces the error to less than 0.01 arcsec rms. Together with the other two instruments on Hinode (the X-Ray Telescope (XRT) and EUV Imaging Spectrometer (EIS)), SOT is poised to address many fundamental questions about solar magneto-hydrodynamics. Note that this is an overview, and the details of the instrument are presented in a series of companion papers.

Abstract: The Hinode Solar Optical Telescope (SOT) is the first space-borne visible-light telescope that enables us to observe magnetic-field dynamics in the solar lower atmosphere with 0.2 – 0.3 arcsec spatial resolution under extremely stable (seeing-free) conditions. To achieve precise measurements of the polarization with diffraction-limited images, stable pointing of the telescope (<0.09 arcsec, 3σ) is required for solar images exposed on the focal plane CCD detectors. SOT has an image stabilization system that uses image displacements calculated from correlation tracking of solar granules to control a piezo-driven tip-tilt mirror. The system minimizes the motions of images for frequencies lower than 14 Hz while the satellite and telescope structural design damps microvibration in higher frequency ranges. It has been confirmed from the data taken on orbit that the remaining jitter is less than 0.03 arcsec (3σ) on the Sun. This excellent performance makes a major contribution to successful precise polarimetric measurements with 0.2 – 0.3 arcsec resolution.

Abstract: Astronomical Observations / Instruments / Design Methods and Project Management / Telescope Optics / Stray Light Control / Telescope Structure and Mechanisms / Pointing and Control / Active and Adaptive Optics / Thermal Control / Integration and Verification / Observatory Enclosure / Observatory Sites /

Abstract: A special reflecting Schmidt telescope is used to observe celestial objects The telescope has an aperture of 4m, f ratio of 5, and a 5° field of view Its optical axis is fixed and tilted 25° to the horizontal that runs from south to north The celestial objects were observed for 15 h as they passed through the meridian The shape of the reflecting Schmidt plate has to be changed with each different declination δ and in the tracking process This is achieved with active optics The sky area to be observed is -10° ≤ δ ≤ +90° There are plans to place ~4000 optical fibers on the telescope focal surface that will lead to a dozen spectrographs