TY - JOUR A1 - Koopmans, L. V. E. A1 - Bruyn, A. G. A1 - Wambsganß, Joachim A1 - Fassnacht, C. D. T1 - A radio-microlensing caustic crossing in B1600+434? N2 - First, we review the current status of the detection of strong `external' variability in the CLASS gravitational B1600+434, focusing on the 1998 VLA 8.5-GHz and 1998/9 WSRT multi-frequency observations. We show that this data can best be explained in terms of radio-microlensing. We then proceed to show some preliminary results from our new multi-frequency VLA monitoring program, in particular the detection of a strong feature (~30%) in the light curve of the lensed image which passes predominantly through the dark-matter halo of the lens galaxy. We tentatively interpret this event, which lasted for several weeks, as a radio-microlensing caustic crossing, i.e. the superluminal motion of a micro-arcsec-scale jet-component in the lensed source over a single caustic in the magnification pattern, that has been created by massive compact objects along the line-of-sight to the lensed image. Y1 - 2001 UR - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/18700 UR - http://xxx.uni-augsburg.de/pdf/astro-ph/0004285 SN - 1-538-81076-5 ER -