2026/03/31 by Yukio Katsukawa, Y. Katsukawa, J. C. del Toro Iniesta +89
Physics and Astronomy · Engineering · #Solar and Space Plasma Dynamics #Optical Polarization and Ellipsometry #Adaptive optics and wavefront sensing
paper · doi:10.1007/s11207-026-02696-0
Abstract The Sunrise balloon-borne solar observatory is equipped with a one-meter aperture optical telescope, offering a unique platform for uninterrupted seeing-free observations across ultraviolet, visible, and infrared wavelengths from altitudes higher than 33 km. For the third flight of the upgraded Sunrise observatory conducted in 2024, now called Sunrise iii , a new spectro-polarimeter called the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) was developed for observing near-infrared wavelength ranges around 770 nm and 850 nm. These wavelength ranges contain many spectral lines, including two of the Ca ii infrared triplet, K i D1 and D2 lines, and multiple Fe i lines, that are sensitive to solar magnetic fields and velocities in the photosphere and chromosphere. SCIP consists of a grating spectrograph in which polarimetric measurements are conducted using a rotating waveplate as a modulator and polarizing beam splitters placed in front of the cameras. The spatial and spectral resolutions are 0.21'' <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>0.21</mml:mn> <mml:mo>″</mml:mo> </mml:msup> </mml:math> and 1×105 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>1</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> </mml:math> , respectively, and a polarimetric sensitivity of 0.03% (1 σ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>σ</mml:mi> </mml:math> ) of the continuum intensity is achieved with a 10 s integration time per a resolution element. To achieve high-precision detection of small polarization signals, we carefully designed the optical and mechanical systems, polarization components, control electronics, and onboard data processing. Together with the other post-focus instrumentation developed for Sunrise iii , the Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) and the Tunable Magnetograph (TuMag) visible imaging spectro-polarimeter, SCIP provides novel observations that help elucidate energy transfer and time-dependent phenomena across the solar photosphere and chromosphere.