Infrared variability properties of the blazar 3C 279

Abstract

The long-term (about 27 years) near-infrared K light curve is constructed from the published literature for the blazar 3C 279. The Jurkevich method is adopted to analyse the periodicity, and a strong 7.1 ± 0.44 yr period is found, suggesting that the next near-infrared outburst will occur in 2002/03. The correlation between colour index (spectral index) and magnitude is discussed, and a significant correlation between (J - H) and K is found with a correlation coefficient r = 0.72 (p = 2.0 × 10-10), which is consistent with Brown et al.'s proposal.