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

Africa Array GPS Network - ACRA-ACRA P.S.
Start: 25-Jan-2011
End: 06-Apr-2015
Nyblade, Andy, 2011, Africa Array GPS Network - ACRA-ACRA P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5513W9N