[NTG-context] place figure at the top left corner of the header

Hello list, I need to place a figure with its topleft corner on the topleft corner of the header. The figure would be large as the textframe and covering all the header and part of the textframe, leaving the text flow below the figure. In other words, a normal figure \textwidth large, but starting out of the textframe, at the header top, as if the textframe had the same topleft corner of the header. Which is the best way to obtain it? Do I need a custom page makeup, a layer or simply configuring \placefigure? Thank you, Massi