6 Summary and conclusions

We carried out follow-up spectroscopy of 178 Case galaxies in the zone $\alpha = 8^{\rm h} \div 16^{\rm h}$, and $\delta = +29^{\circ} \div +38^{\circ}$,classified in the Case catalog with some code, indicating the presence of the emission doublet [OIII]$\lambda\lambda$4959, 5007, and not observed in the previous follow-up studies. One of the Case candidates shows quasar-like features in the spectrum. Nine Markarian galaxies have been observed additionally in the same sky region. We present the redshifts, equivalent widths and flux ratios of strong emission lines for 142 galaxies. In 44 objects we have not detected emission lines (in blue). In half of them we could detect the common absorption features: CaII H and K, G-band, MgIb and measured their redshifts. The rest objects have too noisy spectra.

We make a preliminary classification of all emission-line galaxies similar to that of Salzer (1989b). We combined his more detailed types SS, DHIIH, HIIH, all with HII-region type spectrum and of low enough luminosity, into one general type -- BCGs.

We conclude that Case ELGs (without added Markarian galaxies) give the high fraction of BCGs -- about 70% of all galaxies with strong enough emission lines, and about 52% of all Case galaxies, marked with some code of the presence of [OIII] line. Among the ELGs coded with "vs'', "s'' and "m'', BCGs comprise up to 86%.

The redshift distribution of the detected ELGs shows no undersampling up to $z\approx 0.04$, and thus these galaxies can be used to study their large-scale spatial distribution up to the distances of $120\,{h}^{-1}$ Mpc. Concatenation of the Case BCG sample with those from the new Hamburg/SAO survey, bording the Case sample from the North, and with SBS BCG sample, closing the large region of about 3000 square degrees, will open new perspectives for studying the spatial distribution of BCGs, the effects of environment on BCG properties and the problems of dwarf galaxy formation and evolution.

Acknowledgements

We acknowledge the partial support of this project by INTAS grant No. 94-2285. This work was carried out with financial support of Russian Ministry of Science and Technology for the 6 m telescope of SAO RAS (BTA, reg. number 01-43), partial support from RFBR grant No. 96-2-16398, and from the Russian Cosmoparticle Physics Center "Cosmion''. The authors are grateful to T.X. Thuan for his support of the initial phase of this project, to S.I. Neizvestny and A.Yu. Kniazev for their help in the observations, to J.J. Salzer and D. Weistrop for sending the results of their observations, and P. Pesch for the reprints of the Case catalog articles. The authors are pleased to thank J.J. Salzer for reading the manuscript and useful suggestions. Authors are thankful to an anonymous referee for useful suggestions, which improved the original version significantly. This research has made use of the NASA/IPAC Extragalactic Database (NED).