The yearbooks 1850-1862 contain magnetic recordings from six observatories: STP (St. Petersburg), EKA (Ekaterinburg, Catherinburg), BAR (Barnaul), NER (Nertchinsk), SIT (Sitka in Alaska) and PEK (Peking in China). In four of these observatories (STP, EKA, BAR and NER) continuous hourly magnetic recordings were made both of horizontal intensity (H) and of declination (D). In Sitka (SIT) recordings were made of declination but not of H, and not for all hours of day. The yearbooks 1851-1855 also contain some data from Peking observatory in China. In Peking there are, however, large gaps in the data and often recordings do not cover whole days.
The locations of these observatories are shown in the map below. The location of the Helsinki observatory (HEL) is also shown. The geographic and corrected geomagnetic coordinates of the stations are listed in table below.
Geomagnetic observatories used in this study: STP (St. Petersburg), EKA (Ekaterinburg) (Catherinburg), BAR (Barnaul), NER (Nertchinsk), PEK (Peking, now Beijing), SIT (Sitka) and HEL (Helsinki, Finland).
| Coordinates of the observatories | ||||
|---|---|---|---|---|
| Observatory | Geographic coordinates | Corr. geomagn. coord (2000) |
||
| Lat. | Lon. | Lat. | Lon. | |
| St. Petersburg (STP) | 59°56' N | 30°18' E | 56.20° | 106.78° |
| Ekateringburg (EKA) | 56°49' | 60°35' | 52.74° | 133.79° |
| Barnaul (BAR) | 53°20' | 83°57' | 49.03° | 156.68° |
| Nertchinsk (NER) | 51°19' | 119°36' | 45.78° | 192.39° |
| Sitka (SIT) | 57°06' | 224°42' | 59.77° | 280.20° |
| Peking (PEK) | 36°57' | 116°29' | 31.06° | 188.90° |
| Helsinki (HEL) | 60°10' | 24°57' | 56.59° | 102.30° |
