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

Hastings GPS Network - DEN3-Denbury3cGPS2011 P.S.
Start: 10-Oct-2011
End: 09-Sep-2019
Dixon, Timothy H., 2016, Hastings GPS Network - DEN3-Denbury3cGPS2011 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5Q52N0P