XRBCAT is a catalog of X-ray binaries, based on the van Paradijs (1996) compilation, and updated by Nick White to include all the new (mostly transient) systems discovered since then up until the last update (see below). The information in XRBCAT is basic and does not attempt to be complete. It includes the name of the source, the position, the pulse or orbital period (if one is known), the object class, a flux (a maximum and, if available, a minimum), and an optical V magnitude (if available). To reference XRBCAT, please use the following acknowledgment: "This paper utilized the HEASARC XRBCAT X-ray Binary catalog". Since it is a very time consuming task to keep track of all the new sources and discoveries, there may be incomplete or missing sources. This catalog was last updated on April 22, 1998. This is a service provided by NASA HEASARC .