We present results from a search for a radio transient associated with the LIGO/Virgo source S190814bv , a likely neutron star-black hole ( NSBH ) merger , with the Australian Square Kilometre Array Pathfinder .
We imaged a 30 { deg } ^ { 2 } field at \Delta T = 2 , 9 and 33 days post-merger at a frequency of 944 MHz , comparing them to reference images from the Rapid ASKAP Continuum Survey observed 110 days prior to the event .
Each epoch of our observations covers 89 \% of the LIGO/Virgo localisation region .
We conducted an untargeted search for radio transients in this field , resulting in 21 candidates .
For one of these , \object [ AT2019osy ] AT2019osy , we performed multi-wavelength follow-up and ultimately ruled out the association with S190814bv .
All other candidates are likely unrelated variables , but we can not conclusively rule them out .
We discuss our results in the context of model predictions for radio emission from neutron star-black hole mergers and place constrains on the circum-merger density and inclination angle of the merger .
This survey is simultaneously the first large-scale radio follow-up of an NSBH merger , and the most sensitive widefield radio transients search to-date .