To cite the service as such, we suggest the following BibTeX entry:
@MISC{vo:ucac4_scs, year=2012, title={The fourth U.S. Naval Observatory {CCD} Astrograph Catalog ({UCAC4})}, author={Zacharias, N. and Finch, C. T. and Girard, T. M. and Henden, A. and Bartlett, J. L. and Monet, D. G. and Zacharias, M. I.}, url={http://dc.zah.uni-heidelberg.de/ucac4/q/s/info}, howpublished={{VO} resource provided by the {GAVO} Data Center} }
Some services have additional advice or requests on citing in their copyright information. For this service, that is: