Distribution of the distances to a subset of the Bolocat sources inside our target regions from Ellsworth-Bowers et al. (2014) shows that a large fraction of the sources locate around 5 kpc, and a smaller fraction of the sources locate around 10–12 kpc. The mean of the distances is 5.9 kpc, and the median is 5.1 kpc. The shaded gray area represents the area inside which the number of sources accounts for 90% of the total sources.