We present the results of an archival search for Trans-neptunian objects (TNOs) in an ecliptic field observed with Subaru in 2002. The depth of the search allowed us to find 20 new TNOs with magnitudes between R=24 and 27. We fit a double power law model to the data; the most likely values for the bright and faint power law exponents are alpha_1=0.73_{ -0.09}^{ +0.08} and alpha_2=0.20_{ -0.14}^{ +0.12}; the differential number density at R=23 is sigma_{ 23}=1.46_{ -0.12}^{ +0.14} and the break magnitude is R_{ eq}=25.0_{ -0.6}^{ +0.8}. This is the most precise measurement of the break in the TNO luminosity function to date. The break in the size distribution corresponds to a diameter of D = 90+-30 km assuming a 4% albedo.
Categories: astro-ph