Three editions of the Star Catalogue of Tycho Brahe

TL;DR

This paper provides machine-readable versions of Tycho Brahe's three star catalogues, analyzes their accuracy against modern data, and compares findings with previous studies, revealing detailed error distributions and magnitude correlations.

Contribution

It offers the first comprehensive digital versions of all three editions of Brahe's star catalogues and analyzes their accuracy and differences using modern Hipparcos data.

Findings

Magnitudes correlate well with modern values.

Position errors have a width of about 2 arcmin.

Approximately 15% of errors exceed 10 arcmin, often due to copying errors.

Abstract

Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited a shorter version with 777 stars, printed in 1602, and Kepler edited the full catalogue of 1004 stars, printed in 1627. We provide machine-readable versions of the three versions of the catalogue, describe the differences between them and briefly discuss their accuracy on the basis of comparison with modern data from the Hipparcos Catalogue. We also compare our results with earlier analyses by Dreyer (1916) and Rawlins (1993), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of about 2 arcmin, with excess numbers of stars with larger errors (as compared to Gaussian distributions), in particular for the faintest stars. Errors in positions larger than 10 arcmin, which comprise about 15 per cent of the entries, are likely due to computing or copying errors.