Info about Helsinki K-index files

The files Hels_D_K1844-80_06 and Hels_H_K1844-97_05 contain geomagnetic activity indices derived from observations carried out in the Helsinki magnetic observatory. The first file is based on observations of the declination (D) from July 1, 1844 to June 30, 1880. The second file is based on the horizontal component (H) valid from July 1, 1844 to May 31, 1897. There are several gaps in the data series. Both files contain eight 3-hour K-values for each day and the daily activity index Ak. The first K-value in each row corresponds to the interval 0...3 in UT.

The files are formatted as follows:

Field      Char.
- Year       4
- Month      2
- Day        2
- Free       1
- K-values   8
- Free       2
- Daily Ak   3
For further details, see:

Nevanlinna, H., Ketola, A. and Kangas, T., 1992. Magnetic results from Helsinki magnetic-meteorological observatory. Part I: Declination 1844-1853. Finn. Met. Inst. - Geophys. Publ. 27, 155 p.

Nevanlinna, H., Ketola, A., L. HŠkkinen, A. Viljanen, and Ivory, K., 1992. Magnetic results from Helsinki magnetic-meteorological observatory. Part II: Geomagnetic activity 1844-1856. Finn. Met. Inst. - Geophys. Publ. 30, 65 p.

Nevanlinna, H. and Ketola, A., 1993. Magnetic results from Helsinki magnetic-meteorological observatory. Part III: Declination 1854-1880. Geomagnetic activity 1844-1880. Finn. Met. Inst. - Geophys. Publ. 33, 193 p.

Nevanlinna, H. and Kataja, E., 1993. An extension of the geomagnetic activity index series aa from two solar cycles (1844-1868). Geophys. Res. Lett., 20, 2703-2706.

Nevanlinna, H. and Ketola, A., 1994. Magnetic results from Helsinki magnetic- meteorological observatory. Part IV: Declination 1880-1909. Summary of observations 1844-1909. Finn. Met. Inst. - Geophys. Publ. 36, 143 p.