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

SCIGN USGS GPS Network - PALG-Pala GPS P.S.
Start: 16-Jun-2015
End: 19-Jul-2021
Hudnut, Kenneth, Determan, Daniel N., Aspiotes, Aris G., 2015, SCIGN USGS GPS Network - PALG-Pala GPS P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5PV6HP3