Parallaxes of L and T dwarfs

We discuss a new program to measure the parallaxes of a number of L and T dwarfs, objects that bridge the gap between M dwarfs and planets. This pilot project tests the feasibility of using large telescopes with infrared detectors to determine parallaxes at the level of milli-arcseconds (mas). First results show that we are able to achieve the required centroiding precision and simulations indicate that when the final observations come in we should be able to achieve our goal of parallaxes with accuracies of 2 mas. The main problems will be focal plane astrometric distortions and stability.