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The Yale/SMARTS optical-near-IR monitoring program has followed thevariations in emission of the Fermi-LAT monitored blazars in the southern skywith closely spaced observations since 2008. We report the discovery of anoptical-near-IR (OIR) outburst with no accompanying gamma-rays in the blazarPKS 0208-512, one of the targets of this program. While the source undergoesthree outbursts of 1 mag or more at OIR wavelengths lasting for longer than 3months during 2008-2011, only interval 1 and 3 have corresponding bright phasesin GeV energies lasting longer than 1 month. The OIR outburst during interval 2is comparable in brightness and temporal extent to the OIR flares duringintervals 1 and 3 which do have gamma-ray counterparts. Gamma-ray and OIRvariability are very well-correlated in most cases in the Fermi blazars and thelack of correlation in this case is anomalous. By analyzing the gamma-ray, OIR,and supporting multi-wavelength variability data in details, we speculate thatthe location of the outburst in the jet during interval 2 was closer to theblack hole where the jet is more compact and the magnetic field strength ishigher, and the bulk Lorentz factor of the material in the jet is smaller.These result in a much lower Compton dominance and no observable gamma-rayoutburst during interval 2.

The Contrasting Nature of Gamma-Ray/Optical Variability in the Blazar PKS 0208-512 During Successive Outbursts