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DIOGENESS, RESIK (Koronas-F mission)

The CORONAS-F Solar Observatory was launched on July 31, 2001 into the polar orbit. Among dozen instruments aboard this medium-size satellite there were also two Bragg crystal spectrometers provided by Poland: RESIK and DIOGENES. The instruments were developed in wide international co-operation. The Consortium involved IZMIRAN, the Astronomical Institute of the Czech Academy of Sciences, two British institutes (the Mullard Space Science Laboratory and the Rutherford Appleton Laboratory) and the Naval Research Laboratory from the USA. Polish spectrometers were designed to investigate the soft X-ray spectra flares in the energy range between 2 and 10keV and allowed to observe not only the flare spectra but also the spectra of solar corona in the periods of lower solar activity.

DIOGENESS was uncolimatied scanning fla crystal spectrometer, which  was observing  solar flare from 25 August 2001 to 17 September 2001onboard  Russian satellite CORONAS–F. Although the instrument was short-lived, it was possible to obtain over one hundred and forty spectra from eight solar flares of M and X class X-rays. The basic part of the instrument was a set of four flat crystals that allowed to record high-resolution spectra of Si xiii X-ray lines (6.65 Å), S xv (5.04 Å), and Ca xix (3.18 Å). Due to the unique setting of one of the measuring sections (the dispersion planes of the two crystals observing the Ca xix line area were in the opposite orientation), the instrument operated as a Dopplerometer: it was possible for the first time to record “absolute” spectral line shifts caused by coronal plasma movement along the line of view. The spectra recorded with the DIOGENESS device are characterized by the best spectral resolution to date, among those registered with satellite devices.

The RESIK (REntgenovsky Spektrometr s Izognutymi Kristalami) instrument, consisting of two double-channel X-ray spectrometers, designed to observe solar active region and flare plasmas. The wavelength coverage, 3.3 Å – 6.1 Å, includes emission lines of Si, S, Cl, Ar, and K and in third diffraction orders, the wavelength range includes He-like Fe lines (1.85 Å) and Ni lines (1.55 Å) with dielectronic satellites, emitted during intense, hot flares. The instrument is believed to be the best calibrated space-borne crystal spectrometer flown to date. The principal aims of RESIK are the measurement of relative and absolute element abundances in the emitting plasma and the temperature distribution of plasma (differential emission measure) over the temperature interval 3 MK and 50 MK.

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