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The observations were made with the GoldCam spectrograph used in
conjunction with the 3K1K CCD detector. We used a
2''
229'' slit with the grating 09 (316 grooves mm-1)
in its first order, and a GG 375 order separation filter. This filter
cuts off all second-order contamination for wavelengths blueward of
7400Å which is the wavelength region of interest here. This
instrumental set-up gave a spatial scale along the slit of 075
pixel-1, a scale perpendicular to the slit of 2.7Å pixel-1, a spectral range of 3500-7500Å and a spectral
resolution of
5Å. These parameters permitted to cover
simultaneously the blue and red spectral range with all the lines of
interest in a single exposure and with enough spectral resolution to
separate important emission lines as H
4340 and
[O III]
4363, and H
6563 and [N
II]
6584. Normally, short exposures were used (5 minutes) in
order to detect strong emission lines, to measure redshifts and make
some crude classification.
Reference spectra of an Ar-Ne-He lamp were recorded to provide a
wavelength calibration. The spectrophotometric standard star Feige 34
from Massey et al. ([1988]) was observed for the flux
calibration at least once a night. No effort was made to orient the
slit along the parallactic angle, so line flux ratios could be
spectrophotometrically inaccurate. The observations were complemented by
dome flats, bias-, and dark frames. The seeing was about 3(FWHM).