Figure 5: The lens system JVAS B0218+357. Top right: the measurement of time delay of about
10 days from asynchronous variations of the two lensed images [16]. The upper left panels show the
HST/ACS image [241] on which can be seen the two images and the spiral lensing galaxy, and the
radio MERLIN+VLA image [17] showing the two images together with an Einstein ring. The bottom
panel shows the 
-ray lightcurve [37], in which, although the components are not resolved, the
sharpness of the variations allows a time delay to be determined (at 11.46 ± 0.16 days, significantly
greater than the radio time delay). Image reproduced with permission from [37]; copyright by AAS.
-ray lightcurve [37], in which, although the components are not resolved, the
sharpness of the variations allows a time delay to be determined (at 11.46 ± 0.16 days, significantly
greater than the radio time delay). Image reproduced with permission from [37]; copyright by AAS.