Observations of the debris disk around the solar-like star HD 107146 reveal the disk (nearly) transiting an extended background galaxy. By using out-of-transit observations to model the galaxy, we show it to be smooth and well modelable. When subtracting this model from the edge-of-transit observation, attenuation by dust of the debris disk in the line-of-sight can be seen. From this we calculate the column density of the dust. The results of this new way of detecting debris dust agree with previous work, however at increasing distance from the star we find an increasing column density, suggesting dust segregation