20 years of continuous robotic observation: the two STELLA telescopes

Abstract

The STELLA robotic observatory consists of two 1.2m alt-az telescopes, which were built by Halfmann Telescopes in the early 2000s. It is located at the Izaña Observatory at the Canary Islands. It was the first robotic telescope world-wide feeding a high-resolution échelle spectrograph (R=55,000) and is still unique in its combination with an imaging telescope. High-resolution spectroscopy on STELLA-2 is complemented with a wide field-of-view (FoV) imaging camera (FoV: 22′) on STELLA-1. The first data in fully robotic mode were collected in 2006; operations have been ongoing uninterrupted for twenty years. The primary design goals of the robotic software– flexibility and reusability– allows seamless integration of new instruments. The primary pipelines produce science-ready data within a few hours. The primary photometric pipeline provides fully flat-fielded imaging data, including a world-coordinate system (WCS) solution and tentative photometric zero points. The spectroscopic pipeline delivers one-dimensional spectroscopic data; orders are not merged. Level two pipelines create light curves of point sources in recurring fields for STELLA-1 and radial velocity data for the sources, as well as metallicity, log(g), Teff and vsin(i) for STELLA-2.