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Z Cam Stars in the Twenty-First Century

Volume 42 number 1 (2014)

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Mike Simonsen
AAVSO, 49 Bay State Road., Cambridge, MA 02138; mikesimonsen@aavso.org
David Boyd
5 Silver Lane, West Challow OX12 9TX, England; davidboyd@orion.me.uk
William Goff
13508 Monitor Lane, Sutter Creek, CA 95685; b-goff@sbcglobal.net
Tom Krajci
Center for Backyard Astronomy, P.O. Box 1351, Cloudcroft, NM 88317; tom_krajci@tularosa.net
Kenneth Menzies
318A Potter Road, Framingham MA, 01701; kenmenstar@gmail.com
Sebastián Otero
AAVSO, 49 Bay State Road, Cambridge, MA 02138; sebastian@aavso.org
Stefano Padovan
Barrio Masos SN, 17132 Foixà, Girona, Spain; stefano@stefanopadovan.com
Gary Poyner
67 Ellerton Road, Kingstanding, Birmingham B44 0QE, England; garypoyner@blueyonder.co.uk
James Roe
85 Eikermann Road-174, Bourbon, MO 65441; jim.roe@asemonline.org
Richard Sabo
2336 Trailcrest Drive, Bozeman, MT 59718; rsabo333@gmail.com
George Sjoberg
9 Contentment Crest, #182, Mayhill, NM 88339; george.y.sjoberg@gmail.com
Bart Staels
Koningshofbaan 51, Hofstade (Aalst) B-9308, Belgium; staels.bart.bvba@pandora.be
Rod Stubbings
2643 Warragul, Korumburra Road, Tetoora Road, VIC 3821, Australia; stubbo@sympac.com.au
John Toone
17 Ashdale Road, Cressage, Shrewsbury SY5 6DT, England; enootnhoj@btinternet.com
Patrick Wils
Aarschotsebaan 31, Hever B-3191, Belgium; patrickwils@yahoo.com

Abstract

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.