ISSN 1845–8319 THE MODERNIZED HORIZONTAL SPECTROGRAPH AT THE ONDŘEJOV OBSERVATORY

Abstract. The large horizontal solar telescope 50/35000 cm has been changed from Czerny-Turner type to a multicamera system recently. The change of the diffraction grating from Baush & Lomb to the Richardson one enabled to use up to 5 CCD high-speed cameras working simultaneously in diagnostically important spectral lines (Hα, Hβ, HeI D3 and CaII H or K and CaIR 8542 Å). The Hα slit-jaw imaging system has been improved and another cameras operating in white light and for a full disk image taken in Hα were also implemented. The VDS Vosskuehler CCD cameras can sample several spectra and filtergrams per second in two modes (1280 x 1024 pxs, 12 bits, or 1280 x 512 pxs, 12 bits). The data are stored, archived and reduced to DF and FF in an offline regime. The observer and computer room has been moved to the basement of the pavilion to minimize possible interferences of the sensitive optical device. The observation system is flexible enough as concerns observations of dynamic phenomena of solar activity (flares, prominences, filaments, spicules, etc.). The description of the solar optical spectrograph can be found at th