2017MNRAS.469.1545F

The sample of known star clusters, the fundamental building blocks of galaxies, in the Milky Way is still extremely incomplete for objects beyond a distance of 1-2 kpc. Many of the more distant and young clusters are compact and hidden behind large amounts of extinction. We thus utilized the deep high-resolution near-infrared surveys UGPS and VVV to uncover so far unknown compact clusters and to analyse their properties. Images of all objects in the area covered by these two surveys, which are listed as galaxy in SIMBAD, have been inspected and 125 so far unknown stellar clusters and candidate clusters have been identified. Based on the frequent associations with star formation indicators (nebulosities, IRAS sources, H II regions, masers) we find that the typical cluster in our sample is young, at distances between 1-10 kpc and has a typical apparent radius of 25 arcsec. We suggest more systematic searches, e.g. at all positions of 2MASS extended sources to increase the completeness of the known cluster sample beyond distances of 2 kpc.