This thesis describes a set of surveys for Trans-neptunian objects (TNOs)performed using different observational techniques for detecting slow moving objects in order to characterize their size distribution. A considerable amount of effort has been spent developing tools to automate these algorithms. The study of the TNO size distribution provides a window into the properties of these leftover planetesimals, the protoplanetary disk, and the evolution of the giant planets, casting light on thecomplex relationship between them and the rest of the disk.The first chapter describes the application of a simple search algorithm to data obtained to search for irregular satellites of Uranus. We discovered 72 TNOs over two nights. The sky coverage and sensitivity of this survey allowed us to place the first independent detection of a break in the TNO luminosity function and consequently in the size distribution.The second chapter reports on the massive application of the “shift and add”technique to a whole night of Subaru SuprimeCam data. By staring at a single field near opposition over the course of a photometric night the sensitivity to faint objects was increased to magnitude R-27 objects. The 20 detections are among the faintest and most challenging ever achieved from the ground, showing that the size distribution of TNOs changes smoothly to a shallower power law behavior as smaller objects are considered.In the third chapter we apply a single image detection algorithm to observations taken within a 10° band around the ecliptic with HST/ACS. The complexity of these data given the superior resolution and extra parallax from the orbiting observatory motivated a different search algorithm that yielded 14 new TNOs. We obtained colors for a two and detected an equal mass binary, but the main result is the compilation of enough faint TNOs with accurate orbital information to describethem as dynamically hot and cold. Although both populations’ luminosity functions differ for bright objects, the break magnitude and its behavior for fainter objects are consistent. This is in agreement with collisional evolution models and implies a different origin but a close evolution between these two sub-populations.PFCHA-BecasDoctor en Filosofía Mención Astronomía156p.PFCHA-BecasTERMINADA