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

Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S.
Start: 29-Jun-1999
End: 03-Jun-2004
Smith, Robert B., 1999, Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5ZW1J82

Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S.
Start: 29-Jun-1999
End: 14-Nov-2022
UNAVCO Community, Smith, Robert B., 1999, Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T53N21QW

Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S.
Start: 03-Jun-2004
End: 14-Nov-2022
UNAVCO Community, 1999, Yellowstone Hotspot GPS Network - GTRG-Great Rift P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5794319