2. Observations

Observations were carried out with the Cigale instrument (Boulesteix et al. 1983; Amram et al. 1991) at the 6 m telescope (SAO Russia) between 1991 and 1994, the 3.6 m telescope at ESO in 1990 and 1995 and the 3.6 m telescope at CFH in Hawaii in 1995. IPCS detector was used at the SAO 6 m and ESO 3.6 m telescopes.
For the 6 m telescope observations, CIGALE was attached at the F/4 prime focus and mainly consists of a scanning Perot-Fabry interferometer with a focal reducer, followed by a magnetically focussed Image Photon Counting System (IPCS), giving pixels of 30 m on a side (Afanasiev et al. 1987). The final aperture ratio is f/2.43 and the pixel sizes are given in Table 3 (click here). The IPCS, with a time resolution of 1/50 s and zero readout noise enables one to scan the interferometer rapidly (typically 10 to 20 s per channel), avoiding sky transparency and seeing variation problems during long exposures.
Calibrations before and after the observation were obtained by scanning the narrow Ne 6599 Å line under the same conditions as the observation, i.e. through the telescope.
For observations at ESO 3.6 m telescope the instrument is slightly the same but the aperture ratio is F/2.5 and the pixel size is 0.91'' on the sky.
For CFHT observations we used SIS focal reducer in FP mode attached at F/8 Cassegrain focus. The CCD detector used was Loral 3 with of read out noise and pixel size on the sky is 0.68''. Due to the read out noise it is impossible to have short exposures like IPCS, so typical time exposure is basically 5 min for each step and we scan only one cycle.
Different Perot-Fabry etalons were used, depending on the observed wavelength and on the velocity range in the galaxy (Table 2 (click here)).
Different interference filters were also used to select redshifted emission lines, main characteristics are given in Table 3 (click here).

  

Identification reference interference Finesse scanned free spectral Spectral

wavelength order channels range (km s^-1) resolution

#1 6563 Å 795 25 24 377.4 20000

#2 6563 Å 501 21 32 598.8 10000

   

Name Coordinates (1950) Date and place of Time Interference filter PF Line Pixel

observations Exposure (s) Used observed size

NGC 404 Oct.1993 (SAO) 8000 6559 Å, 13 Å #2 0.75''

Oct.1992 (SAO) 9120 6585 Å, 14 Å #1 [NII] 6584 Å 0.67''

Aug.1991 (SAO) 7200 5009 Å, 58 Å #1 [OIII] 5007 Å 0.67''

NGC 708 Oct.1994 (SAO) 10240 6668 Å, 23 Å #2 0.92''

Oct.1994 (SAO) 10880 6687 Å, 26 Å #2 [NII] 6584 Å 0.92''

NGC 1052 Oct.1992 (SAO) 17760 6617 Å, 11 Å #1 [NII] 6584 Å 0.67''

Oct.1994 (SAO) 13200 6617 Å, 11 Å #2 [NII] 6584 Å 0.92''

Oct.1993 (SAO) 13240 6602 Å, 11 Å #2 0.75''

NGC 2974 Fev.1995 (CFHT) 9600 6628 Å, 12 Å #2 [NII] 6584 Å 0.68''

Fev.1995 (CFHT) 9600 6606 Å, 25 Å #2 0.68''

NGC 5846 May.1990 (ESO) 12000 6608 Å, 31 Å #1 [NII] 6584 Å 0.91''

NGC 5866 Oct.1992 (SAO) 5760 6586 Å, 14 Å #1 0.67''

Oct.1992 (SAO) 7200 6603 Å, 13 Å #1 [NII] 6584 Å 0.67''

NGC 5898 Fev.1995 (CFHT) 7040 6611 Å, 10 Å #2 0.68''

NGC 6868 Aug.1995 (ESO) 9600 6646 Å, 24 Å #2 [NII] 6584 Å 0.91''

NGC 7014 Aug.1995 (ESO) 11400 6694 Å, 27 Å #2 [NII] 6584 Å 0.91''

NGC 7332 Oct.1993 (SAO) 8320 6602 Å, 11 Å #2 [NII] 6584 Å 0.75''

Oct.1993 (SAO) 8320 6587 Å, 14 Å #2 0.75''

Oct.1994 (SAO) 12160 6587 Å, 14 Å #2 0.92''

Table 3: Journal of observations. SAO: 6 m telescope (Russia), ESO: 3.6 m telescope La Silla (Chile), CFHT: 3.6 m telescope Hawaii (USA)