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Abstract

The data set contains hourly mean values (HMV) of the horizontal magnetic field component H as measured at the geomagnetic observatory Huancayo for 1935 to 1985. Huancayo (IAGA code HUA) is located close to the magnetic equator and is operated by Instituto Geofisico del Peru. The HMVs were taken from the World Data Centre Kyoto (WDC Kyoto) and existing data gaps (in total some 19 years from the 1960ies, 1970ies and 1980ies) were filled in by typing handwritten records of the HMV at GFZ. These handwritten records were monthly tables that were received as digital images from geomagnetic observatory Huancayo or that were received as microfilms from World Data Centre Boulder, Colorado. We also produced digital images of these microfilms. The values from the WDC Kyoto are definitive values; the monthly tables presumably also contain definitive values. Corrections to HUA HMVs from WDC Kyoto: There is a known error in the time stamping of the HUA HMVs prior to 1948 (before 1948 the data was reported in local time, rather than universal time). This error is corrected in the present dataset. Also, an attempt was made to correct for a jump in the HMV time series at this time. For further corrections, see Matzka et al, 2017. Please note that a dataset based on the data provided here will be submitted to the WDC Kyoto at a later stage and might undergo further modifications. The data file is in ASCII format and contains blank-separated first the year (YYYY), the month (MM), the day (DD) followed by the 24 HMVs of H (format HHHHH) in nanotesla (nT), starting with the HMV for 00 to 01 universal time. Geomagnetic observatories are described in e.g. Jankowski and Sucksdorf (1996).