4 Results of observations

In this section we present the results of the spectra processing. We divided the presentation of the observed galaxies into the two main groups. In Tables 2 and 3 we give some general parameters, line intensities and equivalent widths for 142 galaxies with the detected emission lines. We summarize data in Table 4 for the remaining 44 galaxies where we have not detected emission lines (in the blue part of the spectrum). One Case object CG 273 appeared to be a distant QSO. Its parameters are described separately after the main data. We present in Fig. 1 the spectra of seven emission-line galaxies and that of the quasar CG 273, in order to illustrate the main activity types in our sample.

4.1 The main observational parameters

The structure of the tables is as follows:
Table 2. Column 1 gives the object name from the Case or Markarian catalogs. Columns 2 and 3 give right ascension and declination on the epoch 1950.0 according to the original Case and Markarian catalogs. The coordinates for the Case catalog objects were obtained by the Catalog's authors from the objective-prism plates of Case survey. The estimated accuracy (rms) for $\alpha$ lies within $\pm$ 3'', for $\delta$ within $\pm$ 6'' (Pesch & Sanduleak 1983). For Markarian galaxies the errors of coordinates usually lie inside 2'' (Lipovetsky 1986). Column 4 gives the eye-estimated apparent photographic magnitudes according to the same sources. The apparent photographic magnitudes for Case catalog objects are eye-estimated from the objective-prism plates as the density of the continuum near 4500 Å. As was shown by Salzer et al. (1995) the mean difference between Case magnitudes $m_{\rm CG}$ and $m_{\rm B}$ is $m_{\rm B}\, {-}\, m_{\rm CG} = 0.25$,while the scatter about the mean is $\sigma_{m_{\rm B}} \approx 0.6$.We present here the original CG magnitudes in order not to mix the CG magnitude values which were derived in the same homogeneous manner with the $m_{\rm B}$ estimates and measurements for small part of galaxies given in various sources. For the Markarian galaxies apparent photographic magnitudes $(m_{\rm pg})$ were taken from the Zwicky catalog (Zwicky et al. 1961-1968). Column 5 gives heliocentric velocity as determined from our spectra. Less accurate entries are marked by colon. In Sect. 5.3 we discuss the estimate of errors of heliocentric velocities which follow from comparison with the data from CfA catalog (Huchra et al. 1995) and which have rms about 100 km s^-1. In Col. 6 we present the estimates of the absolute photographic magnitudes not corrected for the Galaxy extinction, which are derived from the heliocentric velocities of the Col. 5. The other names of the galaxies are given in Col. 7.

Table 3 contains the spectral information for the galaxies from Table 2. In Col. 1 we give the same name as in Col. 1 of Table 2. By an asterisk before the object name we mark the objects for which the spectra were obtained with AIP CCD detector. They are in general of better quality. In Col. 2 we give the IAU-type name of the galaxy for quick and comfortable reference to the same object in Table 2. In Col. 3 we cite the original emission-line code of the galaxy for the strength of [OIII] doublet according to the Case catalog. In Cols. 4 and 5 we give the uncorrected for internal and Galaxy extinction flux ratios of ([OII]$\lambda$3727)/H$\beta$ and ([OIII]$\lambda$5007)/H$\beta$, respectively. The Galaxy extinction in this sky region is very low. As for the possible internal extinction, it can be significant for some of the galaxies, but for most of them due to low enough signal/noise ratio it was difficult to do flux correction. So, for homogeneity all the line ratios were given only as the observed ones. In Cols. 6, 7 and 8 we present the equivalent widths of H$\beta$, [OII]$\lambda$3727 and [OIII]$\lambda$5007 respectively. In Col. 9 we make an attempt of classification similar to that of Salzer (1989b) for emission-line galaxies, but without precise information on the size of the galaxies. Since we use only the parameters of excitation and luminosity, some uncorrectness may be present, but we expect that in general this classification correctly reflects the distribution of types in our sample. For the lack of good information on object sizes we joined under BCGs all the galaxies with HII-region spectrum type using Salzer's determination of BCG type as composed from HIIH, DHIIH and SS types. We separated also several galaxies as DANS type in order not to mix this small group of very low excitation dwarfs with other HII-galaxies. For some of the galaxies with weaker emission in [OIII] lines the classification may be ambiguous, especially for border parameters of the line strength or absolute magnitude (BCG or DANS, DANS or SBN). So we mark these objects after the suggested classification by symbol "?'' to indicate the uncertainty of the suggested type.

In Table 4 we present the information about 44 galaxies where emission lines have not been detected. Either common galaxian absorption features were detected (CaII H and K, G-band, MgI) or the spectra were too noisy to extract any information besides the absence of strong emission lines. In Col. 1 the object name from the Case or Markarian catalogs is given. Columns 2 and 3 are the catalog's right ascension and declination at the epoch 1950.0. The apparent photographic magnitude of a galaxy from the Case or Markarian catalogs is given in Col. 4. In Col. 5 we put the heliocentric velocity determined from absorption lines. Less reliable values are marked by colons. Absolute photographic magnitudes in Col. 6 are based on the data from Cols. 4 and 5. The emission-line code (strength of [OIII]$\lambda\lambda$4959, 5007 doublet) as is given in the Case catalog is reproduced in Col. 7. In Col. 8 we give either the absorption features in the spectra, from which the redshift was determined, or refer to the spectra as inconclusive ones due to a quite low S/N ratio. In Col. 9 we give alternative names of Case galaxies, if they are already known.

4.2 Quasar CG 273

One of the Case candidates appeared to be a distant and bright AGN. This is CG 273 ($\alpha = 09^{\rm h}39^{\rm m}05^{\hbox{$.\!\!^{\rm s}$}} 8$, $\delta = +35^{\circ}36'42''$,$m_{\rm CG} = 18\hbox{$.\!\!^{\rm m}$}0$). Only one prominent emission line is seen in the wavelength range 3600-5500 Å. This broad emission line is centered at $\lambda$4673 Å and its FWHM is $\approx 50$ Å. We identify it with the MgII doublet $\lambda$2798 Å, the corresponding redshift is 0.670. With the Hubble constant 75 km s^-1 Mpc^-1 and q₀=0.5 its absolute photographic magnitude $M_{\rm CG} = -25$ mag, which places CG 273 to the class of quasars. We show its spectrum in Fig. 1.

  

Figure 1: Examples of spectra of Case emission-line objects detected in this work. The strongest emission lines [OIII] $\lambda\lambda$4959, 5007, H$\beta$ and [OII] $\lambda$3727 are seen on most of the spectra. The only line [OII] $\lambda$3727 is seen in the spectrum of CG 775, and only MgII $\lambda$2800 - in the spectrum of QSO CG 273