1 Introduction

The galaxies of the Local Group (LG) are our closest neighbors in the Universe. All the galaxies within 1.25 Mpc from its barycentre are considered members of the LG (Courteau & van den Bergh 1999). The LG contains galaxies covering a large range of luminosities, metallicities, and morphological types, but the large majority are dwarf irregular and spheroidal galaxies. Their close distance enables the study of their content in much more detail than in more distant galaxies. For this reason, a new deep survey, the Local Group Census (LGC) has been undertaken in all the LG galaxies above $\rm {Dec}=-30^\circ$. The survey aims at highlighting all populations with strong emission lines, such as, H II regions, planetary nebulae (PNe), supernova remnants, luminous blue variables, and Wolf-Rayet stars.

One of the first targets of the LGC was the dwarf irregular galaxy Sextans B, which at a distance of $1.32\pm0.12$ Mpc (Sakai et al. 1997) is located at the outer fringes of the Local Group. Although its radial velocity is consistent with membership of the LG, it might form, together with NGC 3109, Antlia, Sextans A and perhaps AM1013-394A, a physical association of galaxies lying just beyond the boundaries of the LG, which would be the nearest association outside the LG (van den Bergh 2000). The resolved stellar population of Sextans B is dominated by red giants (Sakai et al. 1997), with a prominent contribution of intermediate-age asymptotic branch stars. A young population is also present, indicating a complex, low-rate and likely discontinuous star formation throughout the galaxy lifetime (Tosi et al. 1991; van den Bergh 2000). A dozen H  II regions are known (Strobel et al. 1991), but no PNe have been identified prior to this study (Jacoby & Lesser 1981).

The narrow-band images ([O  III], H$\alpha$+ [N  II], [S  II], He  II) presented in this paper show five new candidate PNe in Sextans B. The observations are described in Sect. 2, and data reduction and analysis in Sect. 3. In Sect. 4, we present the candidate PNe, and discuss the results in Sect. 5.