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Active galactic nuclei (AGNs) are well-known to exhibit flux variabilityacross a wide range of wavelength regimes, but the precise origin of thevariability at different wavelengths remains unclear. To investigate therelatively unexplored near-IR variability of the most luminous AGNs, we conducta search for variability using well sampled JHKs-band light curves from the2MASS survey calibration fields. Our sample includes 27 known quasars with anaverage of 924 epochs of observation over three years, as well as onespectroscopically confirmed blazar (SDSSJ14584479+3720215) with 1972 epochs ofdata. This is the best-sampled NIR photometric blazar light curve to date, andit exhibits correlated, stochastic variability that we characterize withcontinuous auto-regressive moving average (CARMA) models. None of the other 26known quasars had detectable variability in the 2MASS bands above thephotometric uncertainty. A blind search of the 2MASS calibration field lightcurves for AGN candidates based on fitting CARMA(1,0) models (damped-randomwalk) uncovered only 7 candidates. All 7 were young stellar objects within the{\rho} Ophiuchus star forming region, five with previous X-ray detections. Asignificant {\gamma}-ray detection (5{\sigma}) for the known blazar using 4.5years of Fermi photon data is also found. We suggest that strong NIRvariability of blazars, such as seen for SDSSJ14584479+3720215, can be used asan efficient method of identifying previously-unidentified {\gamma}-rayblazars, with low contamination from other AGN.

SDSSJ14584479+3720215: A Benchmark JHK Blazar Light Curve from the 2MASS Calibration Scans