The Carrington event from August 28 to September 5, 1859: a search for a major geophysical event.
The beginning of September 1859 was the occasion of the first and unique observation of a giant solar white light flare, (a bright zone appearing in the middle of a sunspot). Auroral displays were observed at low latitudes and geomagnetic observatories recorded exceptional storms. This event is known as the Carrington event after the astronomer who observed it, this astronomer was at the time a very rare case of an observer ready for an unexpected observation, moreover, he had taken the precaution to be assisted by an independent observer. Not only this set of events were observed by one of the first scientific communities to operate in network but it impacted the telegraphic network. Its effects were numerous but as electricity was not yet fully understood (the Maxwell publications date from 1865 and the application of the equations to physical problems date from Heaviside beginning in 1872) these data are dispersed in a variety of sources and in a variety of formats.
Several types of documents come into view: the first are the direct solar observations of the sunspots and of the white flare, second: magnetic observations from the network of magnetic stations initiated by General Sabine in the British Empire and third observations of the auroral displays by a variety of observers both professional and naïve with an extension to the tropics. Those found their way in the scientific literature and can be retrieved using the usual techniques of bibliographical research, moreover, part of the scientific community saw them already as related events and some were even published together. Other science observations as early ozone measurements are much more diverse as the chemists of the time did not make the link between solar activity, electricity and atmospheric chemistry, only one observer increased the frequency of his observations to link them with the event, these data found their way to a scientific publication but other ozone data might still be accessible in forgotten archives. In the case of the perturbations on the telegraph, only the press of North Eastern America reported abundantly on them but as telegraphic procedures were not standard, it is difficult to deduce quantitative data. In continental Europe, the press did not report anything but some descriptions found their way to the scientific literature as the electrical telegraph was used for the synchronisation of meteorological and magnetic observations. The perturbations of the Australian telegraph were found very well described in a yearly report of the state of Victoria. It is almost sure that perturbation reports are still lost in archives. The situation is even worse for possible biological consequences as agricultural statistics as well as morbidity and mortality records were not standardised and on time scales too long to detect the event.
In conclusion, this kind of historical research based on a variety of sources would benefit of the PERICLES method for the constitution of its basic data base.
Geophysical Research Abstracts, Vol. 15, EGU2013-657, 2013, EGU General Assembly 2013
The Carrington event from August 28 to September 5, 1859 : impact on communications, atmospheric chemistry and economy from the historical record.
Image: Carrington drawing of the sets of sunspots of September 1, 1859, the zones marked A and B was the location of a white flash lasting at least five minutes. (Carrington, 1859).