in the 2FGL catalog analysis, because it is based on different multifrequency information. For this reason, these methods could be in principle combined to increase the fraction of associated UGSs and the efficiency of the association. Further developments of this new association method will be investigated in a forthcoming paper [@massaro12b].

We thank the anonymous referee for the his/her comments. F. Massaro is grateful S. Digel for their fruitful discussions for all the comments helpful toward improving our presentation. We also thank to A. Cavaliere, D. Harris, J. Grindlay, J. Knodlseder, P. Giommi, N. Omodei, H.Smith and D. Thompson for their suggestions. The work at SAO and at Stanford University is supported in part by the NASA grant NNX10AD50G, NNH09ZDA001N and NNX10AD68G. R. D’Abrusco gratefully acknowledges the financial support of the US Virtual Astronomical Observatory, which is sponsored by the National Science Foundation and the National Aeronautics and Space Administration. F. Massaro acknowledges the Fondazione Angelo Della Riccia for the grant awarded him to support his research at SAO during 2011 and the Foundation BLANCEFLOR Boncompagni-Ludovisi, n’ee Bildt for the grant awarded him in 2010 to support his research. TOPCAT[^7] [@taylor2005] was used extensively in this work for the preparation 