The Hamburg/SAO survey for emission-line galaxies I. A first list of 70 galaxies

We present first results(1) of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAG Special Astrophysical Observatory, Russia) which is based on the digitized objective-prism photoplates database of the Hamburg Quasar Survey (HQS). The main goal of this survey is the search for emission-line galaxies (ELG) in order to create a new deep sample of blue compact galax ies (BCG) in a large sky area. Another important goal of this work is to search for new extremely low-metallicity galaxies. We present the first results of spectroscopy obtained with the 2.2m telescope at the German-Spanish Observatory at Calar Alto, and with the 6m telescope at the Russian Special Astrophysical Observatory. The primary ELG candidate selection criteria applied were a blue continuum (near lambda 4000 Angstrom) and the presence of emission lines close to lambda 5000 Angstrom recognized on digitized prism spectra of galaxies with magnitudes in the range B = 16.(m)0 - 19.(m)5. The spectroscopy resulted in the detection or/and quantitative spectral classification of 74 emission-line objects. Of them 55 are newly discovered, and 19 were already known as galaxies before. 11 of the latter have redshifts and are known ELGs. For most of the known galaxies emission line ratios were measured for the first time and an improved classification is presented. 47 objects are classified as BCGs, one as Sy2 galaxy, six as possible LINERs, and four as new QSOs. The remaining galaxies do not show significant HP and [OIII] lambda lambda 4959, 5007 Angstrom emission lines, and are likely either low-ionization starburst or dwarf amorphous nuclear starburst galaxies.