A <i>UBVR</i> CCD Survey of the Magellanic Clouds

Abstract

We present photometry and a preliminary interpretation of a UBVR survey of the Large and Small Magellanic Clouds, which covers 14.5 deg 2 and 7.2 deg 2, respectively. This study is aimed at obtaining well-calibrated data on the brighter, massive stars, complementing recent, deeper CCD surveys. Our catalog contains 179,655 LMC and 84,995 SMC stars brighter than V ∼ 18.0, and is photometrically complete to U ∼ B ∼ V ∼ 15.7, and R ∼ 15.2, although stars in crowded regions are selectively missed. We provide tentative cross-reference between our catalog stars and the stars with existing spectroscopy. Our photometry agrees well with the photoelectric work in V and B–V, and agrees well for U–B for the bluest stars, but we find a large discrepancy (0.3 mag) in the U–B color at U–B ∼ 0.0. Examination of the colors of stars with known spectral types suggests that the problem may lie with the photoelectric data. We discuss the population of stars seen towards the two Clouds, identifying the features in the color-magnitude diagram, and using existing spectroscopy to help construct H-R