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tokens: with distance estimates (Table A.1 ), as seen from the Galactic pole. Dynamically confirmed black holes are marked in orange circles, whereas BH candidates are indicated by yellow stars. Distance ranges are represented with bars while the systems with lower limits are indicated by arrows that follow the same colour index. Some systems are overlapped with other. Each faint white ring in the background image represents an additional 1.5 kpc from the Sun. Objects seem to concentrate along the direction towards the Galactic centre. The dynamical BHT in the upper right of the figure is BW Cir. Background image credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech). Fig. 3 Top : the distribution of dynamically confirmed BHs (circles) and BH candidates (stars) in the Galactic plane, using the Hammer projection. (Background image credit: Mellinger 2009 ). Some of the symbols are overlapped by others, especially in the Galactic centre region. Bottom : histogram of the distribution of BH transients in Galactic longitude ( left ) and latitude ( right ). A 10 bin size in longitude and 5 bin in latitude were used respectively. Here we revisit the problem of the size of the Galactic population of BHs, based on the currently observed sample, which is heavily affected by extinction. Duerbeck (1984) modelled the density distribution of several interacting binaries in the Galaxy. In a similar way, we want to obtain the density of Galactic BHTs and analyse the height distribution (; Col. 8 in Table A.1 ). Only 35 out of the 59 detected BHTs have estimated distances. Because of their transient nature, we have only detected those systems that went into outburst. Therefore, in a given period of time, we have only discovered a fraction of them (e.g. the brightest and/or closest BHTs – with the shortest outburst cycles). Thus, to derive the true distribution, we first need to find the maximum radial distance at which completeness of the sample is guaranteed, i.e. such that none of the X-ray outbursts are missed. The completeness of the sample can be obtained from the analysis of the density of objects as a function of the radial distance that is projected onto the Galactic plane (). The latter is derived from the Galactic latitude and the distance listed in Cols. 5 and 6 of Table A.1 . Here, we have used 31 out of the 35 BHTs with a reported distance (we exclude the four systems with lower or upper limits). In addition, we consider a conservative 50% uncertainty in systems with only a rough estimate of distance. To derive the density of objects () up to a radii , we count the number of BHTs lying in cylinders or radius centred at the Sun and infinite height (). However, given the large uncertainties with distance, in some cases an object could be placed in more than a single cylinder within errors. To account for this effect, for each object we randomly generate 10 000 values that assume a Gaussian distribution. Here, we naively assume the distance errors follow this sort of