The following information obtained from UNAVCO's online DOI system:
(https://www.unavco.org/data/doi/search/search.html)

COCONet GPS Network - CN51-SombreroIslandAI P.S.
Start: 12-May-2015
End: 05-Sep-2017
UNAVCO Community, 2015, COCONet GPS Network - CN51-SombreroIslandAI P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5MS3R2G