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Дата изменения: Wed Apr 14 14:21:19 1999
Дата индексирования: Sat Sep 11 20:28:58 2010
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Spectral observations and data reduction

All results presented below were obtained by observations with the Russian 6m telescope, mainly in the snap-shot mode during 16 runs between December 1995 and June 1998. The spectrograph SP-124 attached to the Nasmyth-1 focus of the telescope and equipped with a new Photometrix CCD-detector PM1024 (with $24\times24\mu$m pixel size) was used in most of the runs. We used the gratings either with 300 grooves/mm or with 600 grooves/mm (see journal of observations in Table 1). Due to an experimental set-up of the CCD detector, it was not properly optimized, and significant vignetting prevented us in several runs in 1995 and early 1996 to get spectra in the UV ( $\lambda \leq 4000$ Å). Various spectral set-ups were used with dispersions from 2.4 to 5.5 Å/pixel. The long slit with a length of 40$\arcsec$ was used. The slit width was 2$\arcsec$ in almost all observations. The scale along the slit was 0.4$\arcsec$ or 0.5$\arcsec$/pixel. Normally, short exposures were used (2-5 minutes) in order to detect strong emission lines, to measure redshifts and make some crude classification. Several spectra were taken with the Long Slit spectrograph (LSS in Table 1) (Afanasiev et al. [1995]) at the 6m telescope prime focus equipped with a CCD-detector on base of an ISD015A chip ( $530\times580$ pixels, with rectangular pixel size $18\times24\mu$m), produced at SAO RAS. Long slit spectra ( $2\arcsec\times180\arcsec$) were obtained with the grating having 650 grooves/mm and a dispersion 3.1 Å/pixel, and a scale along the slit of 0.41$\arcsec$/pixel. Reference spectra of an Ar-Ne-He lamp were recorded before or after each observation to provide a wavelength calibration. The spectrophotometric standard stars from Massey et al. ([1988]) were observed for flux calibration at least twice a night.

All observations and data aquisition with the spectrograph SP-124 have been conducted under software package NICE in MIDAS, described by Kniazev & Shergin (1995).