The first Palomar Gattini-IR catalog of J-band light curves: construction and public data release

Palomar Gattini-IR is a wide-field, synoptic infrared time domain survey covering ≈ 15000 sq. deg. of the sky at ≈ 1-3 night cadence to a depth of J≈ 13.0 and ≈ 14.9 Vega mag in and outside the Galactic plane, respectively. Here, we present the first data release of J-band light curves of 2MASS sources within the survey footprint covering approximately the first four years of operations. We describe the construction of the source catalog based on the 2MASS point sources, followed by exposure filtering criteria and forced PSF photometry. The catalog contains light curves of ≈ 286 million unique sources with 2MASS magnitudes of $J < 15.5$ mag, with a total of ≈ 50 billion photometric measurements and ≈ 20 billion individual source detections at signal-to-noise-ratio $> 3$. We demonstrate the photometric fidelity of the catalog by i) quantifying the magnitude-dependent accuracy and uncertainty of the photometry with respect to 2MASS and ii) comparing against forced PGIR aperture photometry for known variable sources. We present simple filtering criteria for selecting reliable photometric measurements as well as example Python notebooks for users. This catalog is the largest compilation of nightly cadence, synoptic infrared light curves to date, comparable to those in the largest optical surveys, providing a stepping stone to upcoming infrared surveys in the coming decade.