Secular variation on the territory of the Czech Republic and reduction of the magnetic survey to the epoch 2010.5

A recent stage of the magnetic surveying activities in the Czech Republic was started in the fifties by setting up a basic network of the first order. It consists of 199 points. Complete measurements of three components, D, H, and Z, were carried out in 1976-78 and 1994-96. Since 1970 six selected points have been revisited approximately every two years. Five of them are situated close to the Czech boundaries, the last one inland. The repeat station network was complemented by another inland station in 2003. The repeat station measurements, together with the data from neighboring observatories, were now used to reduce the data from the last magnetic survey to the epoch 2010.5 and new magnetic charts were drawn. The accuracy of the results and their comparison with IGRF model is also discussed