Merge branch 'shu_fge_offsets' into 'master'

Add shu fge offsets metadata

See merge request !243

geomagio/Metadata.py

@@ -490,9 +490,9 @@ _INSTRUMENT_METADATA = [
             "channels": {
                 # each channel maps to a list of components to calculate nT
                 # TODO: calculate these lists based on "FGE" type
-                "U": [{"channel": "U_Volt", "offset": 0, "scale": 944.935}],
+                "U": [{"channel": "U_Volt", "offset": 19750, "scale": 944.935}],
                 "V": [{"channel": "V_Volt", "offset": 0, "scale": 964.909}],
-                "W": [{"channel": "W_Volt", "offset": 0, "scale": 966.893}],
+                "W": [{"channel": "W_Volt", "offset": 48050, "scale": 966.893}],
             },
             # this info should get updated when available
             "electronics": {