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

UNAVCO GPS Network - PAS1-Passcal #1 P.S.
Start: 13-Nov-2001
End: 01-Aug-2016
Jackson, Michael, 2001, UNAVCO GPS Network - PAS1-Passcal #1 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5GB228S