Cluster AgeS Experiment Catalog of variable stars in the globular cluster ω Centauri ^*,**

¹ Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa, Poland e-mail: [jka;olech;pych;alex]@camk.edu.pl
² Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101, USA e-mail: ian@ociw.edu
³ Las Campanas Observatory, Casilla 601, La Serena, Chile e-mail: wojtek@lco.cl

Received: 26 January 2004
Accepted: 25 May 2004

Abstract

We present results of a photometric survey for variable stars in the field of the globular cluster ω Centauri. The observed region was centered roughly on the cluster core and covered 644 arcmin². The cluster was monitored on 59 nights in 1999 and 2000. A total of 117 new variables were identified. Among them there are 17 RR Lyr-type stars, 35 SX Phe variables and 26 eclipsing binaries. A comprehensive catalog including all variable stars so far reported from the cluster field is presented. We list basic photometric properties and provide finding charts for a total of 392 objects. For 313 of them new  light curves were obtained. The presented sample includes several interesting variables, such as SX Phe stars with extremely short periods of pulsation and several candidates for pulsating K giants. Optical counterparts to 9 X-ray sources detected by XMM and Chandra telescopes were identified: all of them are likely to be foreground variables not related to the cluster.