The modernized solar optical spectrograph at the Ondrejov observatory

One of the two recently modernized medium-size horizontal solar telescopes 50/35000 cm (further on mentioned as HSFA2) has been changed from Czerny-Turner type to a multicamera system. Change of the diffraction grating from Baush & Lomb to the Richardson one enabled to use 4 CCD high speed cameras working simultaneously in 4 diagnostically important spectral lines (H-alpha, H-beta, HeI D3 and CaII H or K). In addition, we have improved the H-alpha slit-jaw imaging system working with the same type of camera. All the 5 used CCD cameras are of the same type and they can sample the spectra and filtergrams at a speed of several images per second. Size of the image is 1280 x 1024 pixels working with dynamical range of 12 bits. The CCD images are stored, archived and reduced to DF and FF in an offline regime. The observer and computer room has been moved to another pavilion floor to minimize possible interferences of the sensitive optical device. Another slit jaw CCD camera operating in white light was implemented to provide information necessary for the remote observer.

The observation system is flexible enough as concerns observations of dynamic phenomena of solar activity (flares, prominences, filaments, etc.) Therefore, the observational program is scheduled for all active phenomena momentarily occurring at the solar disk or limb. The only limitation is weather and season of the year. The program is open for cooperation with other ground based and space born instruments in the frame of existing and future projects. Data and description of the HSFA2 solar optical spectrograph can be found at the http://www.asu.cas.cz/%7Epkotrc/index5.html web page. Experience obtained during the two years' period of its operation is mentioned. Technical details and scientific plans of the spectrograph are outlined and discussed in this contribution.