Numbat is a user friendly software that fits dX-tensor to a set of PCS measurements and a structure from a PDB file. It has also been designed to assist in the semi automatic process of PCS assignment. A detailed description of the software can be found in this publication: Christophe Schmitz, Mitchell J. Stanton-Cook, Xun-Cheng Su, Gottfried Otting, and Thomas Huber (2008). Numbat: an interactive software tool for fitting Δχ-tensors to molecular coordinates using pseudocontact shifts. Journal of Biomolecular NMR. 41:179-189.