Clustered star formation toward Berkeley 87/ON2

Context. Disentangling line-of-sight alignments of young stellar populations is crucial for observational studies star-forming complexes. This task particularly problematic in a Cygnus-X subregion where several components, located at different distances, overlap: the Berkeley 87 massive cluster, poorly known [DB2001] Cl05 embedded and ON2 complex, which turn composed H II regions. Aims. We provide methodology building an exhaustive census objects that can consistently treat large differences extinction distance. Methods. OMEGA2000 near-infrared observations 87/ON2 field were merged with archival data from Gaia , Chandra Spitzer Herschel cross-identifications literature. To address incompleteness effects selection biases arise overlap, we adapted existing methods estimation object classification. also defined intrinsic reddening index, R int new tool separating intrinsically red sources those whose infrared color excess caused by extinction. Finally, introduce method finding based on . Results. find 571 classification related to recent or ongoing star formation. Together other point individual estimates distance extinction, compile catalog 3005 be used further membership work. A 87, (1673 ± 17) pc, estimated as median 13 spectroscopic members accurate EDR3 parallaxes. Conclusions. The flexibility our approach, especially regarding definition, allows overcoming photometric variations order obtain homogeneous catalogs sources. multiwavelength results applying will serve basis disentangling overlapped populations.