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Дата изменения: Sat Nov 25 17:34:13 2000
Дата индексирования: Sat Sep 11 20:32:51 2010
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The Fourth List

As shown in Table 1, among 104 observed emission-line objects 66 (63%) were classified based on the character of their spectra and their absolute magnitudes as H II/BCGs or probable BCGs. Since the main goal of the HSS is an efficient search for new BCGs, the fraction of this type among all confirmed ELGs of the first priority list ($\sim$68 %, or 63 % among all emission-line objects) is encouraging.

The distribution of 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$5007 (see Baldwin et al. ([1981]), Veilleux & Osterbrock ([1987]) for details) in general is similar to that shown in Paper I as may be expected since the selection criteria are identical. Several new BCGs with very strong emission lines located in the metal-poor regions of these diagrams were reobserved later with higher signal-to-noise ratio, and four of them (0951+3841, 1028+3843, 1124+3635 and 1309+3806) are found to have O/H < 1/10 (O/H)$_{\odot}$. A full description of the selection procedure for low-metallicity candidates based on snap-shot spectra is given in Kniazev et al. ([2000]).

The snap-shot spectroscopy of the random selected sample of second priority candidates detected only 4 additional BCG/HII galaxies ($\approx$10%, cf. Table 1). We expect therefore, not much more than $\approx$60 BCGs among the 633 second priority candidates of the $\delta$=35-40 strip.

To find these BCGs efficiently we used additional selection criteria based on the APM, which are fulfilled also by most of the BCGs from the first priority list. For this subsample of 80 candidates spectroscopic information is available for 24 objects: 11 were observed by us due to this selection, 10 were already observed as part of the random sample, and for 3 the information was taken from the literature. Altogether 10 BCGs or probable BCGs were found among them. The current estimate of detection rate for BCGs in the APM selected sample is therefore $\approx$40%.