Copernicus's Heliograph at Olsztyn -- the 500th Anniversary of a Scientific Milestone

TL;DR

This paper uncovers Copernicus's 16th-century heliograph at Olsztyn, revealing it as a novel astronomical measuring device used for precise solar ecliptic longitude measurements, with open access data and models.

Contribution

It identifies and analyzes Copernicus's lattice as a heliograph with a non-local reference meridian, a previously unknown observational technique.

Findings

Copernicus's device was a heliograph for solar measurements.

The device used a non-local reference meridian.

Open access digital models and data are provided.

Abstract

Exactly 500 years ago, Nicolaus Copernicus drew a lattice of lines on a panel above the doorway to his rooms at Olsztyn Castle, then in the Bishopric of Warmia. Although its design has long been regarded as some kind of reflecting vertical sundial, the exact astronomical designation of the lines and related measuring techniques remained unknown. Surprisingly, Copernicus did not refer to his new observational methods in his principal work, \textit{De Revolutionibus}. A data analysis of a 3D model of the panel has, at last, solved the mystery: Copernicus created a new type of measuring device -- a heliograph with a non-local reference meridian -- to precisely measure ecliptic longitudes of the Sun around the time of the equinoxes. The data, 3D model and modeling results of our analysis are open access and available in the form of digital (Jupyter) notebooks.