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X-Ray Emission Line Spectrum of a Coronal Active Region

Naturevolume 214pages4142 (1967) | Download Citation



Two slitless Bragg spectrometers were successfully used on a Sun-pointed Skylark rocket flight (SL 304) on May 5, 1966, to measure the solar X-ray emission below 25 Å. The crystals were of potassium acid phthallate (KAP), with a lattice constant of 13.3 Å, and photons were detected with thin plastic window proportional counters. The rocket launch took place at 0414 h (U.T.) during a period of relatively quiet solar activity. In particular, no solar flares have been reported in a period of several hours around the time of launching. Solar pointing was achieved approximately 100 sec after launch and was maintained until re-entry 274 sec later. The apogee of the rocket was 181 km, giving a negligible atmospheric attenuation, for the X-ray wavelengths being measured, throughout most of the controlled flight. Four spectral scans over the wavelength band 11–25 Å were obtained. The data have been reduced by computer. A full analysis is still proceeding, but this communication reports the emission line identifications so far obtained, several not having previously been seen in the solar spectrum.

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  1. 1

    Blake, R. L., Ap. J., 142, 1 (1965).

  2. 2

    Fawcett, B. C., Gabriel, A. H., and Saunders, P. A. H., Proc. Phys. Soc., 90, 863 (1967).

  3. 3

    Feldman, U., Cohen, L., and Schwartz, M., NASA GSFC Document X–614–68–496.

  4. 4

    Garstang, R. H., Pub. Astro. Soc. Pacific, 78, 399 (1966).

  5. 5

    Kastner, S. O., Omidvar, K., and Underwood, J. H., NASA GSFC Document X–614–66–287.

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  1. University of Leicester

    • K. EVANS
    •  & K. A. POUNDS
  2. University College, London

    • J. L. CULHANE


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