Historical data records at Hurbanovo geomagnetic observatory

Complete text of publication follows. Recordings of the geomagnetic field at the Hurbanovo Geomagnetic Observatory started at the end of the 19th century. The observatory was well known at that time as the observatory of OGyalla (later Stara Dala and Hurbanovo). The oldest registration preserved is most probably from the year 1899. The old variometers recorded the elements of the geomagnetic field onto photographic paper. Nowadays the old magnetograms are being saved in digital form - they are being scanned and saved as a high resolution pictures. Processing of the oldest magnetograms, especially the correct dating of them turned out to be a difficult task, because the description made by the creators were sometimes rather confusing. Some of them will require to be compared with historical data from other observatories. Strong geomagnetic events during the first part of the 20th century were studied in connection with the known events on the Sun and in the interplanetary space, such as the great enhancements of the solar activity and the comas of comets transiting near the Earth.