A&A 516, A28 (2010) Astronomy DOI: 10.1051/0004-6361/201014002 & c ESO 2010 Astrophysics Three editions of the star catalogue of Tycho Brahe Machine-readable versions and comparison with the modern Hipparcos Catalogue F. Verbunt1 andR.H.vanGent2,3 1 Astronomical Institute, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands e-mail:
[email protected] 2 URU-Explokart, Faculty of Geosciences, Utrecht University, PO Box 80 115, 3508 TC Utrecht, The Netherlands 3 Institute for the History and Foundations of Science, PO Box 80 000, 3508 TA Utrecht, The Netherlands Received 6 January 2010 / Accepted 3 February 2010 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, Tychonis Brahe Dani Scripta Astronomica, Vol. II) and Rawlins (1993, DIO, 3, 1), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of 2, 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, which comprise about 15% of the entries, are likely due to computing or copying errors.