4 Discussion

Altogether we have observed 113 objects preselected as ELG candidates on HQS objective prism plates, of which 108 had no previous spectroscopic information. Of those 85 objects (75%) are found to be either ELGs, or quasars. Of 81 detected ELGs, 55 were classified based on the character of their spectra and their absolute magnitudes as H II/BCGs or probable BCGs. According to their line intensity ratios, six galaxies are of the Sy type, five of them probably of type Sy2, while the continuum bump blueward to H$\beta$ in the spectrum of HS 1526+3729 suggests an identification as the Fe II emission line blend typical for Sy1 galaxies. But we caution the relatively low S/N ratio in that part of the spectrum. One very faint object (HS 1214+3801) of absolute magnitude $M_{B}= -11\hbox{$.\!\!^{\rm m}$ }8$ is probably a super-association in the dwarf spiral NGC 4244, or a BCG companion to this subluminous spiral galaxy. Eight candidates are difficult to classify. The remaining 11 ELGs are objects of lower excitation: either starburst nuclei galaxies (SBN and probable SBN) or their lower mass analogs, dwarf amorphous nuclear starburst galaxies (DANS or probable DANS). Since the main goal of the HSS is an efficient search for new BCGs, the fraction of this type among all new detected ELGs ($\sim$68%, or 65% among all emission-line objects) is encouraging.

The distributions of the new HSS ELGs in the line-ratio diagrams [O III]$\lambda$5007/H$\beta$ versus [N II]$\lambda$6583/H$\alpha$ and [O III]$\lambda$5007/H$\beta$ versus [O II]$\lambda$3727/[O III]$\lambda$5007 (see Baldwin et al. ([1981]), Veilleux & Osterbrock ([1987]) for details) in general are similar to those shown in Paper I.

Compared to Paper II, we picked up significantly fewer low-luminosity ELGs ( $M_{ B} \leq -15$). This is partly connected to the modest size of the telescopes used (2 m versus 6 m in Paper II) and the range of apparent brightness of ELG candidates observed for this paper. Probably more important is that the Calar Alto observations prefered apparently bright objects (only 4 fainter than 18.5) due to the back-up status of the measurements which was prompted by a modest weather quality.

Altogether in Papers I through III, we discovered 257 new emission-line objects (14 of them QSOs), and for 35 more galaxies we got quantitative data for their emission lines. Preliminary classification of the 278 ELGs yields 206 confident or probable blue compact/low-mass H II galaxies. Thus a large fraction of BCGs relative to all ELGs is found ($\sim$ 74%) demonstrating the high efficiency of this survey to find galaxies with H II-type spectra on the Hamburg Quasar Survey photoplates. A statistical analysis of this BCG sample, supplemented with galaxies from the next slices of the survey, is underway.