Abstract
Catalogs of the Zurich Observatory contain positional information on sunspots, prominences, and faculae in the late 19th and early 20th centuries. This database is given in handwritten tabular form and was not systematically analyzed earlier. It is different from the sunspot-number time series made in Zurich and was obtained with a larger telescope. We trained a neural-network model for handwritten text recognition and present the database of reconstructed coordinates. The database obtained connects the earlier observations by Spörer with later programs of the 20th century and supplements the sunspot-group catalogs of the Royal Greenwich Observatory. We also expect that the presented machine-learning approach and its deep capabilities will motivate the processing of a wide bulk of astronomical data, which is still given in nondigitized form or as plain scanned images.
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Data Availability
The datasets generated during the current study are available in the GitHub repository github.com/observethesun/zurich_catalogs.
Notes
For neural networks, tensor dimensions are (channels, height, width).
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Acknowledgments
We greatly acknowledge the efforts by e-manuscripta.ch, the digital platform for manuscript material from Swiss libraries and archives. We are also grateful to the group of students of MSU who helped with initial dataset annotation and model validation and the reviewer for valuable comments.
Funding
EI acknowledges the support of RSF grant 21-72-20067.
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Illarionov, E., Arlt, R. Reconstruction of the Solar Activity from the Catalogs of the Zurich Observatory. Sol Phys 297, 79 (2022). https://doi.org/10.1007/s11207-022-02015-3
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DOI: https://doi.org/10.1007/s11207-022-02015-3