Eclipse From the Edge, by Terry Cuttle
For the 2013 hybrid eclipse, I decided on Cape Lopez in Gabon for two reasons, 1) relatively easy access and 2) gave me an opportunity to be right on the edge of the path of totality.
I had been drawn closer to the edge following the 2008 eclipse which I observed from the Jaiyuguan Fort in China, 11km in from the edge of a 220km wide path (5% in). One of my objectives was to image the eclipse with the sun shining on something outside the path of the eclipse as I had never seen an image of this elsewhere. Imaging towards the eclipse allowed me to include the 30 – 50 km distant up to 5,000m high Qilian Shan mountain range. My image of the eclipse can be seen on APOD http://apod.nasa.gov/apod/ap090718.html with the sun shining on the clouds above the mountains. But the experience of the shadow in the sky, baily's Beads and the other edge phenomena were spectacular, leaving me wanting more.
Cape Lopez protruded just into the southern edge of the path. Correcting for the limb profile in some detail and thanks to Dave Herald's excellent Occult 4 program for the assessment, I established that the Cape was about 250m into the corrected path edge. The uncorrected edge was almost 2km further south, with this difference caused by a deep lunar valley. I picked a spot 50m back from the tip of the cape (200m into the calculated edge of the path). I had discussed expected accuracy of the calculations with Dave and this was a far as I was willing to push it.
The display of Bailys Beads was simply stunning. It went on for almost 30 seconds as the Moon skimmed the left side of the Sun with the beads moving and sparkling like a diamond necklace along the left side of the Sun, finally reducing to a spectacular double diamond ring. The bead display continued on for so long that I considered for a while that I was just outside the edge and would miss totality. But totality finally came in clear part of the sky with a beautiful solar max corona dramatically accentuated by the chromosphere which appeared down the left side of the Sun for the whole of the about 27 seconds of totality. The view of the approaching shadow was equally dramatic. Being right on the edge, the approaching shadow was quite different from a centreline view when the shadow approaches spreading out and enveloping the observer. Here looking west, the shadow was all to my right side and it looked just like a deadly serious thunderstorm approaching very rapidly from the horizon over the ocean. All this time the view to the south was relatively bright. I expected to see the edge of the shadow extending at 45 degrees down from the Sun I but did not see that, possibly because the edge is so diffuse and the air relatively clear. The edge of the shadow during totality was quite visible projected on the clouds to the south not clearly defined but brightening from my position outwards. A lighthouse that I could see more than a kilometre away to the south appeared to be slightly brighter..
I have observed four total solar eclipses of less than 30 seconds and they are certainly among the most spectacular. But being right on the edge was absolutely stunning, and I would recommend it to anyone who gets the chance. I suggest that every eclipse chaser should do it at least once. Otherwise you certainly will not have "seen it all".