The distance to the cool T9 brown dwarf ULAS J003402.77-005206.7

Aims. We demonstrate the feasibility of determining parallaxes for nearby objects with the Wide Field Camera on the United Kingdom Infrared Telescope (UKIRT) using the UKIRT Infrared Deep Sky Survey as a first epoch. We determine physical parameters for ULAS J003402.77-005206.7, one of the coolest brown dwarfs currently known, using atmospheric and evolutionary models with the distance found here.Methods. Observations over the period 10/2005 to 07/2009 were pipeline processed at the Cambridge Astronomical Survey Unit and combined to produce a parallax and proper motion using standard procedures. Results. We determined $\pi = 79.6 \pm 3.8$mas, $\mu_{\alpha} = -20.0 \pm 3.7$mas/yr and $\mu_{\delta} = -363.8 \pm 4.3$mas/yr for ULAS J003402.77-005206.7. Conclusions. We have made a direct parallax determination for one of the coolest objects outside of the solar system. The distance is consistent with a relatively young, 1-2 Gyr, low mass, 13-20 $M_{\rm J}$, cool, 550-600 K, brown dwarf. We present a measurement of the radial velocity that is consistent with an age between 0.5 and 4.0 Gyr.