Hubble Space Telescope/NICMOS imaging survey of the Ophiuchus (Lynds 1688) cluster

We present a catalog of near-infrared photometry of young stars associated with the Ophiuchus molecular cloud based on observations made with the Hubble Space Telescope NICMOS3 camera at 1.1 and 1.6 mum. Our survey covers 0.02 deg(2) centered on the dense molecular cores in Lynds 1688. We detect 165 sources at 1.6 mum and 65 sources at 1.1 mum within our estimated completeness limits of 21.0 and 21.5 mag, respectively. An analysis of the cloud extinction, based on existing molecular line maps, suggests that most of the sources lying within the 40 extinction contour of the cloud are probable A V cloud members. Approximately half (58/108) of these sources are previously unpublished. The faint embedded sources revealed by these observations are spatially concentrated in three regions of high stellar space density (N > 10(4) stars pc(-3)). While the spatial distribution of these sources reflects that of the brighter, well-known population of young stars in Ophiuchus, it is distinctly different from the distribution of cool concentrations seen in the submillimeter. Seven new brown dwarf candidates are identified based on their infrared colors and their projected locations on high column density regions of the molecular cloud. Eight new candidate binary and five new candidate triple systems, having separations between 0."2 and 10" (29-1450 AU) are reported. The spatial resolution and sensitivity of these observations reveal five apparent disk/envelope systems seen via scattered light and four nebulous objects with complex morphologies.