5/12/21

 In the Mon R2 cluster, no thorough spectroscopic surveyhas yet been carried out which would usefully distinguish browndwarfs from other young low-mass objects. As a next-best option weconsider careful photometric selection of brown dwarf candidates.Andersen et al. (2006) carried out and published HST photometryfrom the NICMOS filters F165M, F160W, F110W, and F207M; theynote that the filter pair F165M and F160W allow for sensitivity tochanges in the∼1.6휇m H2O absorption feature which emerges andthen deepens at and below∼2900 K. As noted by e.g., Holwerda et al.(2018), spectral types of cool M, L, and T dwarfs can be partiallydistinguished by some combinations of space-borne near-infraredphotometric bands. In Mon R2, we rely on Andersen et al. (2006)’s
photometry in these filters (especially the aforementioned F160Wand F165M) to select cool dwarfs with spectral types later than M6