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

MAGNET - FRG1-FRG1 P.S.
Start: 06-Apr-2017
End: 15-Jul-2018
Blewitt, Geoff, Hammond, William C., Kreemer, Corne, 2017, MAGNET - FRG1-FRG1 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T57D2SXH