The 2017 North American total eclipse has begun to encourage many outreach and citizen-science activities. We describe here a part of the Eclipse Megamovie program, in which we deploy a smartphone app to enable anybody with a GPS-equipped smartphone to record correct images of Baily's Beads (the "Diamond Ring" effect) for subsequent analysis. The multiply over-sampled recordings of 2nd and 3rd contacts, across and along the track, will provide material for unique movie representations of the astronomical phenomenon. After the fact, this highly over-sampled data set can be used to confirm and/or extend detailed satellite topography of the Moon from Kaguya and LRO.

In addition the high angular resolution inherent in the "knife-edge" motion will provide a unique view of the structure of the solar limb itself. The low angular resolution of the smartphone cameras is a handicap, but excellent time resolution and massive oversampling are great advantages. We anticipate public participation in image selection to get the best sequences of last few-millisecond imagery for the science product here, which can follow the known motions of the solar limb due to p-modes and granulation. No comparable database exists, and so the final product of this crowdsourcing will be a public archive of the data and metadata for future studies.

https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/190366