The First Historical Standstill of WW Ceti

Abstract

Z Cam dwarf novae are distinguished from other dwarf novae based on the appearance of so called 'standstills' in their long-term optical light curves. It has been suggested previously that WW Cet might be a Z Cam type dwarf nova, but this classification was subsequently ruled out, based on its long-term light curve behavior. Forty years of historical data for WW Cet has shown no evidence of standstills. WW Ceti is therefore classified as a UG type dwarf nova in the General Catalog of Variable Stars (GCVS) and the International Variable Star Index (VSX). Beginning in the 2010 observing season, WW Cet has been observed to be in a standstill, remaining more or less steady in the 12th magnitude range. Based on this first ever, historical standstill of WW Ceti, we conclude that it is indeed a bona fide member of the Z Cam class of dwarf novae.