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

Mauna Loa GPS Network - SLPC-Sleeping Cave P.S.
Start: 25-Jan-2006
End: 14-Nov-2022
Brooks, Benjamin, Foster, James, 2006, Mauna Loa GPS Network - SLPC-Sleeping Cave P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/WVSV-2M93