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

MAGNET - FRG3-FRG3 P.S.
Start: 10-May-2017
End: 23-May-2022
Blewitt, Geoff, Hammond, William C., Kreemer, Corne, 2017, MAGNET - FRG3-FRG3 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T53N2254