A Digital Photometric Survey of the Magellanic Clouds: First Results From One Million Stars

TL;DR

This paper reports initial results from a large-scale UBVI photometric survey of the Magellanic Clouds, providing high-quality data for over a million stars and discovering more stellar clusters than previously known.

Contribution

It offers a comprehensive description of the survey methodology, data quality, and presents a new catalog of stellar clusters with significant improvements over prior data.

Findings

Photometry of over 1 million stars completed

Discovered 68 stellar clusters, 45% more than previous catalogs

Identified only 12 clusters as old red clump star concentrations

Abstract

We present the first results from, and a complete description of, our ongoing UBVI digital photometric survey of the Magellanic Clouds. In particular, we discuss the photometric quality and automated reduction of a CCD survey (magnitude limits, completeness, and astrometric accuracy) that covers the central 8 by 8 degrees of the Large Magellanic Cloud (LMC) and 4 by 4 degrees of the Small Magellanic Cloud (SMC). We discuss photometry of over 1 million stars from the initial survey observations (an area northwest of the LMC bar covering 2 by 1.5 degrees) and present a deep stellar cluster catalog that contains about 45% more clusters than previously identified within this region. Of the 68 clusters found, only 12 are also identified as concentrations of ``old'', red clump stars. Furthermore, only three clusters are identified solely on the basis of a concentration of red clump stars, rather than as a concentration of luminous (V < 21) main sequence stars. Extrapolating from the current data, we expect to obtain B and V photometry for 25 million stars, and U and I photometry for 10 and 20 million stars, respectively, over the entire survey area.