A gravitationally lensed quasar discovered in OGLE

We report the discovery of a new gravitationally lensed quasar(double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the $\sim$670 sq. deg area encompassing the Magellanic Clouds. The source was selected as one of $\sim$60 "red W1-W2" mid-IR objects from WISE and having a significant amount of variability in OGLE for both two (or more) nearby sources. This is the first detection of a gravitational lens, where the discovery is made "the other way around", meaning we first measured the time delay between the two lensed quasarimages of $-132 approx-102$ days (in the observer frame), and where the fainter image B lags image A. The system consists of the two quasarimages separated by 1.5" on the sky, with $I\approx20.0$ mag and $I\approx19.6$ mag, respectively, and a lensing galaxy that becomes detectable as $I \ approx21.5$ mag source, 1.0" from image A, after subtracting the two lensed images. Both quasarimages show clear AGN broad emission lines at $z=2.16$ in the NTT spectra. The SED fitting with the fixed source redshift provided the estimate of the lensing galaxy redshift of $z \ approx0.9 \pm 0.2$ (90% CL), while its type is more likely to be elliptical (the SED-inferred and lens-model stellar massis more likely present in ellipticals) than spiral (preferred redshift by the lens model).