High-resolution imaging with the International LOFAR Telescope: Observations of the gravitational lenses MG 0751+2716 and CLASS B1600+434

We present Low-Frequency Array (LOFAR) telescope observations of the radio-loud gravitational lens systems MG 0751+2716 and CLASS B1600+434. These produce images at 300 milliarcseconds (mas) resolution 150 MHz. In case 0751+2716, modelling is used to derive a size estimate around 2 kpc for low-frequency source, which consistent with previous 27.4 GHz study in radio continuum Karl G. Jansky Very Large (VLA). This consistency implies that source cospatial core-jet structure forms higher frequencies, no significant lobe emission or further components associated star formation are detected within magnified region lens. B1600+434 two-image where one passes through edge-on spiral lensing galaxy, low frequency allows us limits on propagation effects, namely scattering, galaxy. The observed flux density ratio two lensed 1.19 +/- 0.04 an widths give upper limit 0.035 m^-20/3 integrated scattering column galaxy distance approximately 1 above its plane, under assumption image A not affected by scattering. relatively small compared derived very long baseline interferometry (VLBI) studies differential systems. demonstrate LOFAR excellent instrument studying lenses. also report inability calibrate three observations: from early have less well determined station calibration, third observation impacted phase transfer problems.