Large magellanic cloud near-infrared synoptic survey. I. Cepheid variables and the calibration of the Leavitt Law

We present observational details and first results of a near-infrared (JHK_s) synoptic survey of the central region of the Large Magellanic Cloud (LMC) using the CPAPIR camera at the CTIO 1.5 m telescope. We covered 18 square degrees to a depth of K_s∼16.5 mag and obtained an average of 16 epochs in each band at any given location. Our catalog contains more than 3.5 × 10⁶ sources, including Cepheid variables previously studied at optical wavelengths by the OGLE survey. Our sample of fundamental-mode pulsators represents a nine-fold increase in the number of these variables with time-resolved, multi-band near-infrared photometry. We combine our large Cepheid sample and a recent precise determination of the distance to the LMC to derive a robust absolute calibration of the near-infrared Leavitt Law for fundamental-mode and first-overtone Cepheids with 10× better constraints on the slopes relative to previous work. We also obtain calibrations for the tip of the red giant branch and the red clump based on our ensemble photometry which are in good agreement with previous determinations.