We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305 , independent of the component velocities .
These estimates are based on six epochs of multi-wavelength narrowband images from the Nordic Optical Telescope .
For each pair of lensed images and each photometric band , we determine the microlensing amplitude and chromaticity using pre-existing mid-IR photometry to define the baseline for no microlensing magnification .
A statistical comparison of the combined microlensing data ( 6 epochs \times 5 narrow bands \times 6 image pairs ) with simulations based on microlensing magnification maps gives Bayesian estimates for the half-light radius of R _ { 1 / 2 } = 8.5 ^ { +7.5 } _ { -4.0 } \sqrt { \langle M \rangle / 0.3 M _ { \odot } } light-days , and p = 0.95 \pm 0.33 for the exponent of the logarithmic temperature profile T \propto R ^ { -1 / p } .
This size estimate is in good agreement with most recent studies .
Other works based on the study of single microlensing events predict smaller sizes , but could be statistically biased by focusing on high-magnification events .