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

PBO GPS Network - P269-CowboyCampCN2008 P.S.
Start: 29-Apr-2008
End: 04-Oct-2022
UNAVCO Community, 2008, PBO GPS Network - P269-CowboyCampCN2008 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T55X26ZG