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

MAGNET - SEMS-SEMS P.S.
Start: 17-Feb-2021
End: 06-May-2022
Blewitt, Geoff, Hammond, William C., Kreemer, Corne, 2021, MAGNET - SEMS-SEMS P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/P4GZ-RX11