Long Period Variables in NGC 5128: I. Catalogue

Abstract

The first variable star catalogue in a giant elliptical galaxy NGC 5128 (Centaurus A) is presented. Using multi-epoch observations with ISAAC at the VLT we have detected 1504 red variables in two halo fields covering 10.46 arcmin square. For the variables with at least 10 good measurements, periods and amplitudes were determined using Fourier analysis and non-linear sine-curve fitting algorithms. The final catalogue contains 1146 long period variables with well established light curve parameters. Periods, amplitudes, JsHKs photometry as well as individual Ks-band magnitudes are provided for all the variables. The distribution of amplitudes ranges from 0.3 to a few magnitudes in the Ks-band, with a median value around 0.7 mag. The amplitudes, mean magnitudes and periods indicate that the majority of variables belong to the class of long period variables with semiregular and Mira variables. Exhaustive simulations were performed in order to assess the completeness of our catalogue and the accuracy of the derived periods.