[Tagging] Fixed position GPS receivers

[John Smith]

NASA has a list of 421 of these sites located world wide:

http://igscb.jpl.nasa.gov/network/list.html

"The IGS is a voluntary federation of many worldwide agencies that
pool resources and permanent GNSS station data to generate precise
GNSS products. In general, you can think of the IGS as the
highest-precision international civilian GPS community."