CEGS optical scheme

CEGS permits us to obtain high S/N spectra (100) of stars up to 7th magnitude in the "high-dispersion" mode (R~40000). Use of the CCD with higher sensitivity (back-illuminated) will allowed to increase the limited magnitude. In principe, the CEGS is portable spectrometer independent on the telescope (the size of camera 40x50x60 cm, the size of gratings block - 100x60x20 cm, total weigth - 120kg.) and can be used on other telescopes having coude room.

Coude Echelle/Grating Spectrometer (CEGS) designed by F.A.Musaev (Sov. Astron. Lett., V.19, #8, P.776). Spectrometer and CCD camera attached to the 1 metre "Karl-Zeiss-Jena" telescope of the Special Astrophysical Observatory (a satellite of 6-m telescope) of the Russian Academy of Sciences. CEGS has been constructed for utilization at the 2-metre "Karl-Zeiss-Jena" telescope (F/36) of the Shemakha Astrophysical Observatory of the Azerbaijan Academy of Sciences. At present it is optimised when placed on the coude focal plane (F/36) of the 1-m telescope of SAO. The diameter of collimator beam is 150 mm. The camera ("folded" Schmidt) has a 350 mm focal length (crown glass) with a 45 deg apex angle. The accessible spectral range is ~3200 - ~10200 AA. The CCD camera and the data handling system, developed at SAO, consist of front-illuminated CCD device of 520x580 pixels (pixel size 18x24 mkm) inside a dewar, an electronic controller-interface and a IBM PC AT/486 computer. CEGS offers different operational modes:


The CEGS has been in active operation (7-10 nigths per month) at the 1-m telescope since 1993. A number of scientific programmes in the study of hot and cool stars are currently being realized. The most used mode is "high-dispersion" with a first echelle grating.

The analysis of CCD data performed on the IBM PC compatible computers (AT386+) using the image and spectra processing system DECH developed by Galazutdinov G.A. (Special Astrophysical Observatory, Preprint #92, 1992). This system permits us to realize all the steps in echelle-spectra processing - dark current and background substraction, one-dimensional spectra extraction (particularly, by using the "optimal extraction" method (K. Horne, 1986, PASP, V.98, P.609), flat-field corrections, wavelength calibration, continuum placement and rectification, line identification, equivalent widths and radial velocity measuremnts. The system operates under MS-DOS and can be used with portable computer.