Hinotori Solar X-ray Spectrometer (SOX)
The Hinotori satellite (Tanaka, Y. 1983) carried two Bragg crystal spectrometers for the measurement of the iron emission lines. Each spectrometer has a very simple structure consisting of a fiat quartz crystal and a Na I scintillation counter. No moving part was contained.The lower resolution spectrometer (SOX1) scans a wavelength range of about 1.75 - 1.95 Å, and the higher resolution spectrometer (SOX2) scans a range of about 1.83 - 1.89 Å. Since the Hinotori is a rotating satellite, the spectrometers were designed so as to achieve the wavelength scan by utilizing the satellite spin (Tanaka and Nishi 1978).
A crystal is fixed to the satellite with an angle α to the spin axis (α = 15.9 degree for the SOX1 and α= 51.9 degree for the SOX2). The satellite spin axis is off set from the sun center by 1.2 ± O.5 degree and from a flare by a similar small angle δ. Thus the incident angle θ of a photon to the crystal changes periodically from α-θ to α+θ as the satellite rotates. Defining the phase angle of the satellite spin as φ=ωt (ω denotes spin angular velocity), we obtain sinθ=sinαcosδ+sinδcosαcosφ. From the Bragg reflection condition λ=2d(sinαcosδ+sinδcosαcosωt), and this equation gives a temporal wavelength scan. The wavelength range is scanned twice, back and forth, during each rotation.
Thus the temporal resolution equals half the spin period or 8-11 seconds in actual cases. Note that the sampling rate in wavelength becomes more frequent near the wavelength interval boundaries (φ=O or π)，when the temporal sampling rate is constant. The actual sampling time was set to 15.5 ms, and the maximal wavelength step is typically 0.6 mÅ (SOX1) and 0.15 mÅ (SOX2). The scanning proved to be quite uniform as demonstrated by the spectra obtained.
Further description of the instrument is given by Tanaka et al.(1982).
References
- Tanaka, K., Nishi, K.: 1978, Japanese J. Appl. Phys. Supple., 17, Part 2, 461.
- Tanaka, K. et al.: 1982, Ann. Tokyo Astron. Obs., 18, 237.
- Tanaka, Y.: 1983, Solar Phys., 87, 3.
- Tanaka, K.: 1986, Publ. Astron. Soc. Japan, 38, 225.
Hinotori SOX Data Archive
Hinotori SOX data archiving project was conducted in 2017 -- 2019 led by T. Watanabe (NAOJ). Original binary telemetry data (SIRIUS file) are archived, and converted to FITS format. Programs to read FITS telemetry data are provided in C and IDL.Furthermore, IDL routines are written to extract SOX spectral data from the FITS wrapped telemetry. 28 solar flare spectra are extracted and publicly released (table below).
List of Solar Flare Spectra observed by Hinotori SOX
Those marked with "*" are large flares published in Tanaka, K. 1986.