The sites listed here are those used in the creation of the Kp index, and hence also in the derived ap index. The observatories are listed in the order of their geomagnetic latitude (beginning with the highest one).

#CodeNameLandAktivitätLatLongK=9 (nT)
1LERLerwickScotland1932-heute60°08'358°49'1000
2MEAMeanookCanada1932-heute 54°37'246°40'1500
3SITSitkaAlaska1932-heute57°03'224°40'1000
4ESKEskdalemuirScotland1932-heute 55°19'356°48'750
5LOVLovöSweden1954-200459°21'17°50'600
UPSUppsalaSweden2004-heute59°54'17°21'600
6AGNAgincourtCanada1932-196943°47'280°44'600
OTTOttawaCanada1969-heute45°24'284°27'750
7RSVRude SkovDenmark1932-198455°51'12°27'600
BFEBrorfeldeDenmark1984-heute55°37'11°40'600
8ABNAbingerEngland1932-195751°11'359°37'500
HADHartlandEngland1957-heute50°58'355°31'500
9WNGWingstGermany1938-heute53°45'9°04'500
10WITWitteveenNetherland1932-198852°49'6°40'500
NGKNiemegkGermany 1988-heute52°04'12°41'500
11CLHCheltenhamUSA1932-195738°42'283°12'500
FRDFredericksburgUSA1957-heute38°12'282°38'500
12TOOToolangiAustralia1972-1981-37°32'145°28'500
CNBCanberraAustralia1981-heute-35°18'149°00'450
13AMLAmberleyNew Zealand1932-1978-43°09'172°43'500
EYREyrewellNew Zealand1978-heute-43°25'172°21'500

*) After the IGRF Model 'IGRF 10th generation (revised 2005)'  and http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html