Variable stars in the dwarf irregular galaxy NGC 6822: The photometric catalogue ^*,**,***

¹ INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: [lara.baldacci;gisella.clementini]@bo.astro.it
² Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
³ INAF – Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy e-mail: held@pd.astro.it
⁴ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA e-mail: rizzi@ifa.hawaii.edu ()

Received: 17 July 2004
Accepted: 19 October 2004

Abstract

Deep B, V time-series photometry obtained with the ESO Very Large Telescope has been used to identify variable stars in the dwarf irregular galaxy NGC 6822. We surveyed a arcmin area of the galaxy and detected a total number of 390 candidate variables with the optimal image subtraction technique (Alard [CITE], A&AS, 144, 363). Light curves on a magnitude scale were obtained for 262 of these variables. Differential flux light curves are available for the remaining sample. In this paper we present the photometric catalogue of calibrated light curves and time-series data, along with coordinates and classification of the candidate variables. A detailed description is provided of the procedures used to identify the variable stars and calibrate their differential flux light curves on a magnitude scale.