I knew it was unlikely that I'd catch the whole of the transit, since 4th contact was only at about 8 degrees above the horizon. The roof runner of the observatory blocks the scopes from about 12 degrees altitude and below looking West, but there was also a nearby house and a fence post that could block the last few minutes of Sun. Over the few days before the transit, I watched the Sun in the evening, and noted it setting along the ridge of the nearby house. This meant I would probably loose the last half an hour of the transit so long as the sky stayed clear.