Looking Deep into the Rosette Nebula's Heart: The (Sub)stellar Content of the Massive Young Cluster NGC 2244

K.M. acknowledges funding by the Science and Technology Foundation of Portugal (FCT), grants No. IF/00194/2015 and PTDC/FIS-AST/28731/2017. Part of the research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework program (FP7/2007-2013)/ERC grant agreement No. [614922]. R.J. acknowledges support from NSERC grants. A. S.' s work is supported by the STFC grant No. ST/R000824/1. L.C. acknowledges support from CONICYT-FONDECYT grant No. 1171246. K.P.R. acknowledges CONICYT PAI Concurso Nacional de Insercion en la Academia, Convocatoria 2016 Folio PAI79160052. This research has made use of the Spanish Virtual Observatory (http://svo.cab.inta-csic.es) supported from the Spanish MINECO/FEDER through grant AYA2014-55216.