EGU24-11055, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Digitized continuous magnetic recordings for the August/September 1859 storms from London, UK

Ciaran Beggan1, Ellen Clarke1, Ewelina Lawrence1, Eliot Eaton2, John Williamson1, Keitaro Matsumoto3,5, and Hisashi Hayakawa3,4
Ciaran Beggan et al.
  • 1British Geological Survey, Geomagnetism, Edinburgh, United Kingdom
  • 2School of Earth and Environment, University of Leeds, Leeds, United Kingdom
  • 3Institute for Advanced Research, Nagoya University, Japan
  • 4RAL Space, Oxford, United Kingdom
  • 5Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, USA

Dedicated scientific measurements of the strength and direction of the Earth's magnetic field began at Greenwich and Kew observatories in London, UK, in the middle of the 19th century. Using advanced techniques for the time, collimated light was focussed onto mirrors mounted on free-swinging magnetized needles which reflected onto photographic paper, allowing continuous analogue magnetograms to be recorded. By good fortune, both observatories were in full operation during the so-called Carrington storm in early September 1859 and its precursor storm in late August 1859. Based on digital images of the magnetograms and information from the observatory yearbooks and scientific papers, it is possible to scale the measurements to SI units and extract quasi-minute cadence spot values. However, due to the magnitude of the storms, the periods of the greatest magnetic field variation were lost as the traces moved off-page. We present the most complete digitized magnetic records to date of the ten-day period from 25th August to 5th September 1859 encompassing the Carrington storm and its lesser recognised precursor on the 28th August. We demonstrate the good correlation between observatories and estimate the instantaneous rate of change of the magnetic field.

How to cite: Beggan, C., Clarke, E., Lawrence, E., Eaton, E., Williamson, J., Matsumoto, K., and Hayakawa, H.: Digitized continuous magnetic recordings for the August/September 1859 storms from London, UK, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11055,, 2024.