Focal Plane Package Research Articles

The Hinode Spectro-Polarimeter

The joint Japan/US/UK Hinode mission includes the first large-aperture visible-light solar telescope flown in space. One component of the Focal Plane Package of that telescope is a precision spectro-polarimeter designed to measure full Stokes spectra with the intent of using those spectra to infer the magnetic-field vector at high precision in the solar photosphere. This article describes the characteristics of the flight hardware of the HinodeSpectro-Polarimeter, and summarizes its in-flight performance.

The Solar Optical Telescope for the Hinode Mission: An Overview

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 narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus the Stokes Spectro-Polarimeter (SP). The 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 with performance better than 0.01 arcsec rms. Together with the other two instruments on Hinode (the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer (EIS)), the SOT is poised to address many fundamental questions about solar magnetohydrodynamics. This paper provides an overview; the details of the instrument are presented in a series of companion papers.

The Solar Optical Telescope of Solar-B (Hinode): The Optical Telescope Assembly

The Solar Optical Telescope (SOT) aboard the Solar-B satellite (Hinode) is designed to perform high-precision photometric and polarimetric observations of the Sun in visible light spectra (388 – 668 nm) with a spatial resolution of 0.2 – 0.3 arcsec. The SOT consists of two optically separable components: the Optical Telescope Assembly (OTA), consisting of a 50-cm aperture Gregorian with a collimating lens unit and an active tip-tilt mirror, and an accompanying Focal Plane Package (FPP), housing two filtergraphs and a spectro-polarimeter. The optomechanical and optothermal performance of the OTA is crucial to attain unprecedented high-quality solar observations. We describe in detail the instrument design and expected stable diffraction-limited on-orbit performance of the OTA, the largest state-of-the-art solar telescope yet flown in space.

Solar Optical Telescope onboard Hinode for Diagnosing the Solar Magnetic Fields

The Solar Optical Telescope (SOT) onboard Hinode is a 50 cm aperture telescope to observe the sun in visible lights (388-668 nm) for the first time with high and extremely stable spatial resolution from space. The focal plane package of SOT consists of Broad-band Filter Imager which provides the highest spatial resolution images of the solar photosphere, the Narrow-band Filter Imager which takes 2-dimentional Dopplergram and Magnetogram of photosphere and chromosphere in high cadence and with wide field of view, and the Spectro-Polarimeter which takes full Stokes line profiles to provide the highest precision magnetic field maps of the photosphere. The most outstanding characteristics of SOT is its continuous and uniform data quality with the unprecedentedly high precision and high spatial resolution of 0.2-0.3 arcsec. The door of the telescope was deployed on 25th Oct. followed by a successful SOT first light. Initial check-outs of the instrument were conducted and superior performance of SOT was confirmed. SOT is starting the regular observation of the daily target region on the sun and producing excellent scientific data. Overview of the SOT instrument is summarized and initial results are demonstrated.

THE SOLAR-B MISSION

The Solar-B is the third Japanese spacecraft dedicated for solar physics to be launched in summer of 2006. The spacecraft carries a coordinated set of optical, EUV and X-ray instruments that will allow a systematic study of the interaction between the Sun's magnetic field and its high temperature, ionized atmosphere. The Solar Optical Telescope (SOT) consists of a 50cm aperture diffraction limited Gregorian telescope and a focal plane package, and provides quantitative measurements of full vector magnetic fields at the photosphere with spatial resolution of 0.2-0.3 arcsec in a condition free from terrestrial atmospheric seeing. The X-ray telescope (XRT) images the high temperature (0.5 to 10 MK) corona with improved spatial resolution of approximately 1 arcsec. The Extreme Ultraviolet Imaging Spectrometer (EIS) aims to determine velocity fields and other plasma parameters in the corona and the transition region. The Solar-B telescopes, as a whole, will enable us to explore the origins of the outer solar atmosphere, the corona, and the coupling between the fine magnetic structure at the photosphere and the dynamic processes occurring in the corona. The mission instruments (SOT/EIS/XRT) are joint effort of Japan (JAXA/NAO), the United States (NASA), and the United Kingdom (PPARC). An overview of the spacecraft and its mission instruments are presented.

Science of the X-ray Sun: The X-ray telescope on Solar-B

The X-Ray Telescope (XRT) on Solar-B is designed to provide high resolution, high cadence observations of the X-ray corona through a wide range of filters. The XRT science team has identified four general problems in coronal physics as the primary science goals for our instrument. Each of these goals will require collaborative observations from the other Solar-B instruments: EUV Imaging Spectrograph (EIS) and Solar Optical Telescope Focal Plane Package (SOT). We will discuss the science goals and observations needed to address those goals.

Optical design of a near-ultraviolet coronagraph for a sounding rocket platform

The near-UV (190 to 270 nm) coronal emission lines present a unique opportunity to observe heliospheric plasmas between one and two solar radii. The near-UV coronagraph was specifically designed to obtain observations in these lines from a sounding rocket platform. The design demonstrates that high-resolution, two-dimensional coronal observations in the near-UV are readily achievable within the practical constraints of a sounding rocket. The near-UV coronagraph consists of a reflective, coronagraph telescope followed by an imaging channeled spectrograph. The telescope includes a Lyot stop and an occulter to minimize instrumentally scattered disk radiation. The choice of a mirror objective gives rise to a compact, achromatic telescope with excellent off-axis rejection and good imaging properties. The focal plane package combines a Fabry-Pérot interferometer with a tandem Wadsworth spectrograph to produce a channeled spectrum consisting of a series of two-dimensional (25 x 500 arcsec), narrow-bandpass (~0.1 Å) images at the instrument focal plane. The instrument will produce a number of high-spatial-resolution (< 1 arcsec) coronal images in a single flight.