The Atlas of Radio/X-ray Associations (ARXA, 2010 PASA 27 283)

http://quasars.org/arxa.htm
Eric Flesch, 2010

(copied)
These are 602 570 optical objects which are associated to radio/X-ray detections from the NVSS, FIRST, SUMSS, XMM, Chandra, or ROSAT RASS, PSPC, HRI and WGA survey catalogs. All association detections are shown, across all these catalogs. Also displayed: the calculated probability that the optical object is in turn a quasar, galaxy, star, or erroneous association. The optical object is identified from the literature, if known.


http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=V%2F134

(2015-01-23)
Useful data from a large set of catalogs.

I will use this for identification of X-ray observations of Abell2199.