Z Cam Stars in the Twenty-First Century

Z Cam (UGZ) stars are a small subset of dwarf novae that exhibit standstills in their light curves. Most modern literature and catalogs of cataclysmic variables quote the number of known Z Cams to be on the order of thirty or so systems. After a four-year observing campaign and an exhaustive examination of the data in the AAVSO International Database (AID) we have trimmed that number by a third. One of the reasons for the misclassification of some systems is the fact that the definition of what a Z Cam is has changed over the last eighty-five years. This has caused many stars formerly assumed to be Z Cams or rumored to be Z Cams to be eliminated from the final list. In this paper we present the results of our investigation into sixty-five stars listed at one time or another in the literature as Z Cams or possible Z Cams.