Catalogue of sunspot data extracted from historical drawings
This project is aimed to provide open access to historical sunspot drawings.
We want to make the processing procedure transparent and open for correction.
For instance, the separation of sunspots into groups is a non-trivial task.
Also, different approaches, aimed to compensate the uncertainty of sunspot drawing, result in
discrepancy of sunspot positions defined by various researchers.
Assigning different criteria for the boundary of an object (sunspot, umbra, penumbra, etc.) also result in
a different area of this object. For the benefit of an open discussion, here we describe our technique and
post the processed drawings.
Please feel free to use all data and images. Using any data does not require you to include us as co-authors in your research.
Motivation
We would like historical drawings of the Sun to be presented in the public domain similarly to daily routine solar observations on a modern observatory. We believe the discussion on the nature of the Maunder minimum and the reconstruction of legitimate indices of solar activity should begin with an open database of original and annotated historical solar drawings.
Open access is required for not just tabular sunspot data, but also the original drawings have to be public. Processed historical observations should provide all the restored parameters, such as solar ephemerides, observation time, heliocoordinate grid, latitude and longitude of each object, sunspots divided into groups, boundaries of the penumbra and umbra, and measured sunspot area.
Updates
Publications present the supplementary files as published
in the articles. However, the data are gradually being revised to take into account new information,
for example, by comparison with observations of contemporaries.
The most prominent examples are:
(i) Marcus Welser, the publisher, or the engraver, or someone else involved in publishing
Galilei's letters to Welser, mistakenly rotated August drawings by 90o;
(ii) La Hire's measurements show that Hoffmann forgot to reverse and flip sunspots when combining his drawings
with measurements.
These and other corrections are being included in Data. We recommend using the corrected data from there.
Due to the large amount of data, typos and errors are inevitable. If you find any mistakes, please contact us (n.zolotova at spbu.ru or myagkalapka at gmail.com).
What's new
The analysis of La Hire's observations from 1703 to 1710 has finished and all the images are uploaded.
The manuscript accepted for publication in Solar Physics.
Observations by Hoffmann, Maria Eimmart, and Muller were corrected according to the Parisian observations.
Processing of observations of La Hire and Maraldi 1711-1724 will begin soon.
The Data section is being modified.
Acknowledgements
We are grateful to the SCOOSTEP/PRESTO Steering Committee for the support of the project.
