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

Shumagin GPS Network - LKON-LKON_SHUM_AK2021 P.S.
Start: 23-Aug-2021
End: 14-Nov-2022
Freymueller, Jeffrey T., Grapenthin, Ronni, Elliott, Julie L., 2022, Shumagin GPS Network - LKON-LKON_SHUM_AK2021 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/D0T0-WM93