Station Id: SJG
Location: Cayey, PR
Latitude: 18.1110°N
Longitude: 66.1498°W
Geomagnetic Latitude: 27.62°N*
Geomagnetic Longitude: 6.95°E*
Elevation: 424 meters
Orientation: HDZF

* IGRF values as of 2015.

The San Juan observatory sign.


The Geomagnetism Program has operated an observatory at Puerto Rico since 1903. The current observatory site, consisting of 36 acres in the mountains near Cayey, has been in use since 1965.

Other Operations


Cayey, PR magnetic observatory.
San Juan magnetic observatory.
Absolutes, variations and proton buildings (left to right) at San Juan magnetic observatory, Cayey, Puerto Rico.
* Pictures courtesy of Jeff Fox