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Scholarly History of Commentary on Ptolemy’s Star Catalog: Vogt – 1925

In our last post we had established that it was impossible for Ptolemy to have stolen all of his data from Hipparchus as indirect evidence of the number of stars that would have been included in Hipparchus’ catalog indicate that Ptolemy’s catalog had around $200$ stars that Hipparchus’ presumptive catalog did not. Furthermore, we cited Dreyer and Fotheringham who both showed that errors in the determination of the position of equinoxes and solstices would have resulted in the $1º$ error at the heart of the accusation against Ptolemy, eliminating the need for Ptolemy to have used Hipparchus’ catalog.

Thus, while it’s not necessary that Ptolemy took all of his data from Hipparchus, the possibility remains that he took some. But to determine that, we’d need more information about Hipparchus’ presumed catalog which is what we’ll explore in this post looking at an important 1925 paper by Vogt. Continue reading “Scholarly History of Commentary on Ptolemy’s Star Catalog: Vogt – 1925”

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Scholarly History of Commentary on Ptolemy’s Star Catalog: 137 CE – 1918 CE

I’m going to take a bit of a break from direct progress on the Almagest as we get to the star catalog. This is because there is, what I feel to be a fascinating and important discussion surrounding its legitimacy and I want to explore the history of this discussion, even though almost all of it is outside the range of the SCA period1. Namely, the discussion is whether or not Ptolemy’s star catalog is legitimate, one which he took the measurements himself, or if Ptolemy stole the data from an astronomer that came before him and tried to update it, but failed due to an incorrect value for the rate of precession.

Continue reading “Scholarly History of Commentary on Ptolemy’s Star Catalog: 137 CE – 1918 CE”

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Observing Results Time Lapse

Back in May of this year, I’d had a really good night observing. One of the things I always like is getting new stars added to the catalog. I still have the map I entered into Kingdom A&S in 2019 floating around my house and it’s fun to look back and see how much has gotten added since then. That night of observation added quite a few stars to be pile and inspired me to go back and animate the progress after each observing run which I placed on YouTube and then evidently forgot to share. So here it is!

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Queen’s Prize 2022 – The Astronomical Epoch for Solar and (First) Lunar Models

Thanks to Corona, it’s been quite awhile since we’ve really had an Arts & Sciences competition here in Calontir. While we had a virtual Kingdom A&S in $2020$ the last one we had in person was Queen’s Prize in $2019$.

However, this past weekend we finally had another in person Queen’s Prize and I entered my latest paper revising Ptolemy’s models for use in the present day. My previous entry attempted to update the solar model but contained critical errors1. This was revealed when I started attempting to update the lunar model. Realizing that it was predicting solar positions that would have made the eclipses necessary to calibrate the lunar model impossible, I revisited the solar model and made the necessary corrections.

That, plus the first lunar model were included in this year’s entry which was rewritten using LaTeX for a smoother editing and reading experience as Google’s equation editor was rather poor. The paper ended up being $62$ pages (although roughly $45\%$ of that was front material and appendices) which was a lot to expect anyone to read. As such, I also created a TL;DR version for passerbys.

Continue reading “Queen’s Prize 2022 – The Astronomical Epoch for Solar and (First) Lunar Models”