We present a method for the determination of upper limits on the transverse velocity of the lensing galaxy in the quadruple quasar system Q2237 + 0305 , based on the lack of strong microlensing signatures in the quasar lightcurves .
The limits we derive here are based on four months of high quality monitoring data , by comparing the low amplitudes of the lightcurves of the four components with extensive numerical simulations .
We make use of the absence of strong variability of the components ( especially components B and D ) to infer that a “ flat ” time interval of such a length is only compatible with an effective transverse velocity of the lensing galaxy of { v _ { bulk } } ~ { } \leq~ { } 630 km/s for typical microlenses masses of M _ { \mu lens } = 0.1 M _ { \odot } ( or { v _ { bulk } } ~ { } \leq~ { } 2160 km/s for M _ { \mu lens } = 1.0 M _ { \odot } ) at the 90 % confidence level .
This method may be applicable in the future to other systems .