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

SuomiNet:A  GPS Network - SA15-UMBC P.S.
Start: 26-May-2004
End: 06-Aug-2013
Hoff, Raymond, 2004, SuomiNet-A GPS Network - SA15-UMBC P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5FN14H5