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

MAGNET - GVG4-GVG4 P.S.
Start: 03-Dec-2010
End: 23-Feb-2011
Blewitt, Geoff, Hammond, William C., Kreemer, Corne, 2011, MAGNET - GVG4-GVG4 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5KH0KH1