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Magnetograms are used to record variations in the strength and direction of the Earth’s magnetic field. In the UK measurements were made at eight long-running observatories; Abinger, Eskdalemuir, Falmouth, Greenwich, Hartland, Kew and Lerwick. Original paper magnetograms were recorded using photographic techniques at Kew, Greenwich, Abinger, Hartland, Eskdalemuir and Lerwick Observatories. The magnetogram collection, one of the longest running geomagnetic series in the world, provides a continuous record of more than 160 years of UK measurements. These magnetograms start in the 1840s and end in 1986 at which time digital recording of the magnetic field took over and magnetograms can be produced by computer graphic. The plots show variation in the Earth's magnetic field, typically over a 24-hour period. The collection is a valuable, partly untapped data resource for studying geomagnetic storms, space weather and the evolution of the Earth’s magnetic field. The magnetograms provide insight into: • the Earth’s outer core: long-term change (years to centuries) in the dynamo that sustains our magnetic field • space weather: short-term changes (seconds to days) in near-Earth space and on the ground • space climate: long-term change (decades to centuries) in solar activity and consequences for Earth’s environment All the above have an impact on human activities. For example, bad space weather affects technologies that we increasingly rely on, such as electrical power and GPS networks. In January 2009, the BGS began a project to capture high-quality digital images of the magnetogram collection to provide a back up to the photographic paper originals. The images captured so far are available to search online. Scientists and the general public around the world can now gain easy access to this historical dataset.The programme of work to complete the magnetogram digitisation is ongoing and more will be added, observatory by observatory.