TESELA: a new Virtual Observatory tool to determine blank fields for astronomical observations

The observation of blank fields, regions of the sky devoid of stars down to a given threshold magnitude, constitutes one of the typical important calibration procedures required for the proper reduction of astronomical data obtained in imaging mode. This work describes a method, based on the use of the Delaunay triangulation on the surface of a sphere, that allows for easy generation of blank-field catalogues. In addition to that, a new tool named TESELA, accessible through the Internet, has been created to facilitate the user to retrieve, and visualize using the Virtual Observatory tool ALADIN, the blank fields available near a given position in the sky.