Horizon synthesis for archaeo-astronomical purposes

TL;DR

This paper presents a straightforward numerical method for generating synthetic horizon profiles at archaeological sites using digital elevation models, validated with SRTM data and field measurements.

Contribution

The paper introduces a simple, reliable approach to compute horizon profiles using digital elevation data, applicable for archaeological and astronomical site analysis.

Findings

Method achieves ~0.1° accuracy in azimuth and elevation.

Reliable for horizons beyond ~10 km distance.

Higher resolution DEMs improve accuracy.

Abstract

In this paper I describe a simple numerical procedure to compute synthetic horizon altitude profiles for any given site. The method makes use of a simplified model of local Earth's curvature, and it is based on the availability of digital elevation models describing the topography of the area surrounding the site under study. Examples constructed using the Shuttle Radar Topographic Mission (SRTM) data (with 90m horizontal resolution) are illustrated, and compared to direct theodolite measurements. The proposed method appears to be reliable and applicable in all cases when the distance to the local horizon is larger than ~10 km, yielding a rms accuracy of ~0.1 degrees (both in azimuth and elevation). Higher accuracies can be achieved with higher resolution digital elevation models, like those produced by many modern national geodetic surveys.