Searching for White and Brown Dwarfs in the frame of the MUSYC/CYDER survey

MUSYC (MUltiwavelength Survey by Yale and Chile), and its predecessor, the CYDER (Calan Yale Deep Extragalactic Research) survey are both deep multiwavelength surveys mainly aiming at extragalactic issues; however they were both designed with a strong Galactic component in mind. Therefore they consist not only of multipassband imaging (U BV RI z J K) and wide field multi object spectroscopy - it is also foreseen to create a multi-epoch dataset, thus allowing proper motions to be derived using data of 1 and 45 years baseline. This enables us to identify fast moving objects, and derive tangential velocities of nearby and intrinsically faint objects, such as White Dwarfs (especially cool WDs) and Brown Dwarfs (BDs). For the former, we will be able to study the faint end of the halo-field luminosity function and determine the fraction of baryonic dark matter consisting of WDs. We will be able to put constraints on the volume density of BDs, and determine whether this density actually meets expectations. Here we give a report of work in progress.