1 Introduction

Our search for emission-line galaxies (ELGs) towards nearby voids has been described in detail by Popescu et al. (1996) (Paper I) and Popescu et al. (1997) (Paper II). The project belongs to a larger one that has the aim of finding faint galaxies within the voids (Hopp et al. 1995; Kuhn et al. 1997). In summary, we have undertaken a program to search for dwarf galaxies in voids. The motivation of the project was to examine the question of whether the void regions represent real structures, or whether they merely appear as such due to selection effects. We have especially selected nearby voids which were very well defined in the distribution of normal giant galaxies, in order to overcome some of the limitations of previous surveys. Since there was a hint that emission-line galaxies tend to be less clustered, we chose to search for emission-line objects, but with the aim of finding mainly HII galaxies or BCDs (blue compact dwarf galaxies).

The candidates were selected from the objective prism plates taken from the Hamburg Quasar Survey (HQS) (Hagen et al. 1995). An automated procedure was applied to the low-resolution digitised objective-prism spectra, based on two parameters, the slope of the continuum and the "intensity" of the integrated spectra (see Paper I). The selected candidates were afterwards rescanned with high resolution and the final selected spectra were visually inspected for the presence of emission-lines. The candidates are mainly selected on the presence of the [OIII]${\lambda}$5007 line. In Paper I we presented the catalogue of all emission-line galaxies found with the above mentioned selection criteria and we will refer to this as "List 1". This means that objects fainter than our threshold in "intensity" were not considered. The cut in brightness produces some loss of very faint ELGs, having very little continuum and almost all the flux in the emission-lines. In order to prevent the latter incompleteness we also scanned the photographic plates for such faint objects. We observed all the new candidates with follow-up spectroscopy and produced a second list of ELGs that is given in the present paper. We will refer to this catalogue as "List 2". The extra survey was done only for one of our regions - Region 3 from Paper I (a region North of the Coma Supercluster, $30.5^{\circ}<{\delta}<45.5^{\circ}$, centred around $13.5^{\rm h}$). The results concerning the spatial distribution of all the galaxies found in our Region 3 ("List 1" and "List 2") were presented in Paper II. From the estimates of the expected number of void galaxies we concluded that we did not find an underlying homogeneous void population.