Monthly values of the absolutely measured geomagnetic components D, I, H, Z, F for the period 1866-2015 of Coimbra observatory. Different combinations of three magnetic elements were used to fully specify the geomagnetic field vector: the HDI components were measured in 1866-1951; HDZ in 1951-2006; and DIF in 2006-2015. It should also be noted that the monthly values of the first period (1866-1951) are based exclusively on the averages of absolute measurements (made on average 3 per month), while from 1951 onwards the monthly averages were calculated from the hourly averages obtained from the magnetograms after baseline calibration.

Data used in the manuscript "Homogenization of the historical series from the Coimbra Magnetic Observatory, Portugal", submitted to the data publishing journal Earth System Science Data (ESSD); authors: A. L. Morozova, P. Ribeiro, and M. A. Pais