Determination of time delay from the gravitational lens B1422+231

We present the radio light curves of lensed images of the gravitational lens B1422+231. The observations have been carried out using the VLA at 8.4 and 15 GHz over a period of 197 d. We describe a method to estimate the time delay from the observed light curves. Using this method, our cross-correlation analysis shows that the time delay between images B and A is 1.5±1.4 d, that between A and C is 7.6±2.5 d, and that between B and C is 8.2±2.0 d. When applied to other lensed systems with measured time delays our new method gives comparable results.

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