The first data release of J-VAR: Multi-filter light curves for 1.3 million point-like sources

Context . The Javalambre VARiability survey (J-VAR) is a multi-filter photometric survey conducted at the Observatorio Astrofísico de Javalambre, covering selected regions of the northern sky, and providing time-domain information for the Javalambre Photometric Local Universe Survey (J-PLUS) fields. J-VAR primarily focuses on small bodies of the Solar System, variable stars, and optical transients. Aims . We aim to present and describe the data set of light curves contained in this first data release of J-VAR. Methods . J-VAR observations were conducted in seven filters observed quasi-simultaneously, three SDSS broad-bands (g, r, and i), and four narrow bands of the J-PLUS filter system (J0395, J0515, J0660, and J0861). As J-VAR is executed primarily in multi-epoch mode, with multiple visits to a given field spread over a period of a year, the data were collected under varying atmospheric and sky brightness conditions. We accounted for these variations by employing an ensemble differential-photometry technique to correct the light curves, which were subsequently calibrated using already available J-PLUS photometry. Additionally, we used a classification scheme based on Bayesian neural networks to select a high-confidence sample of point-like sources (stars and quasi-stellar objects (QSOs)). Results . J-VAR DR1 consists of 101 fields, covering about 200 square degrees on the sky and containing the light curves of more than 1.3 million point-like sources in the seven filters. The light curves span an effective magnitude range from 13 to 19, with a photometric root mean square (RMS) precision of 2% down to a magnitude of ∼16 and 5% to a magnitude of ∼18 in the broad-band filters. Furthermore, we calculated and provide a number of different variability indices for the light curves included in this data release.