UPDATED
Rosetta’s last image of Comet 67P/Churyumov-Gerasimenko, taken with the OSIRIS wide-angle camera shortly before impact, at an estimated altitude of about 20 m above the surface.
The initially reported 51 m was based on the predicted impact time. Now that this has been confirmed, and following additional information and timeline reconstruction, the estimated distance is now thought to be around 20 metres, and analysis is ongoing
The image scale is about 5 mm/pixel and the image measures about 2.4 m across.