Magnetic observations at the Prague-Clementinum Observatory were started in July 1839 and data up to 1917 were published in yearbooks Magnetische und meteorologische Beobachtungen zu Prag. In addition to regular daily observations with a typical 2-to 4 hour time step, two categories of data with a higher cadence were provided in the first decade: term-day observations coordinated in the frame of Göttingen Magnetic Union and magnetic storms observations. The data up to 1871 were published in instrumental scale units, from 1872 in physical units. The data were recently digitized, processed and published in cooperation with the colleagues from the Earth Science Institute of the Slovak Academy of Sciences.
All volumes of Magnetische und meteorologische Beobachtungen zu Prag were scanned and are available in pdf at https://www.ig.cas.cz/en/prague-observatory-yearbooks/
The processing of regular daily observations – declination and horizontal intensity – is presented in the paper The geomagnetic data of the Clementinum observatory in Prague since 1839, https://doi.org/10.5194/angeo-39-439-2021 a data can be downloaded from https://doi.org/10.5194/angeo-39-439-2021-supplement.
The processing of term-day and magnetic storm observations is presented in the paper Magnetic storm and term-day observations at the Prague observatory Clementinum in the mid-19th century https://doi.org/10.1002/gdj3.141 and data can be downloaded from https://doi.pangaea.de/10.1594/PANGAEA.936921