Z Cam Stars in the Twenty-First Century


Mike Simonsen
AAVSO, 49 Bay State Road., Cambridge, MA 02138

David Boyd
5 Silver Lane, West Challow OX12 9TX, England

William Goff
13508 Monitor Lane, Sutter Creek, CA 95685

Tom Krajci
Center for Backyard Astronomy, P.O. Box 1351, Cloudcroft, NM 88317

Kenneth Menzies
318A Potter Road, Framingham MA, 01701

Sebastian Otero
AAVSO, 49 Bay State Road, Cambridge, MA 02138

Stefano Padovan
Barrio Masos SN, 17132 Foixà, Girona, Spain

Gary Poyner
67 Ellerton Road, Kingstanding, Birmingham B44 0QE, England

James Roe
85 Eikermann Road-174, Bourbon, MO 65441

Richard Sabo
2336 Trailcrest Drive, Bozeman, MT 59718

George Sjoberg
9 Contentment Crest, #182, Mayhill, NM 88339

Bart Staels
Koningshofbaan 51, Hofstade (Aalst) B-9308, Belgium

Rod Stubbings
2643 Warragul, Korumburra Road, Tetoora Road, VIC 3821, Australia

John Toone
17 Ashdale Road, Cressage, Shrewsbury SY5 6DT, England

Patrick Wils
Aarschotsebaan 31, Hever B-3191, Belgium

Received October 7, 2013; revised November 12, 2013; accepted November 12, 2013


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.