Optical Observing Conditions at Delingha Station

TL;DR

This paper presents a comprehensive multi-year study of the Delingha site in China, evaluating its suitability for optical astronomy and describing the monitoring system for autonomous operation of the SONG-China telescope node.

Contribution

It provides the first detailed quantitative characterization of the Delingha site for optical astronomy and discusses the development of an automated site monitoring system.

Findings

Delingha site has suitable conditions for optical astronomy.

Multi-year data supports site stability and quality.

Monitoring system enables safe autonomous operation.

Abstract

SONG is a global ground based network of 1 meter telescopes for stellar time-domain science, an international collaboration involving many countries across the world. In order to enable a favourable duty cycle, the SONG network plans to create a homogeneous distribution of 4 nodes in each of the northern and southern hemispheres. A natural possibility was building one of the northern nodes in East Asia, preferably on the Qinghai-Tibetan Plateau. During the last decade, a great deal of effort has been invested in searching for high a quality site for ground based astronomy in China, since this has been one of the major concerns for the development of Chinese astronomy. A number of sites on the plateau have been in operation for many years, but most of them are used only for radio astronomy, as well as small optical telescopes for applied astronomy. Several potential sites for large optical instruments have been identified by the plateau site survey, but as yet none of them have been adequately quantitatively characterised. Here we present results from a detailed multi-year study of the Delingha site, which was eventually selected for the SONG-China node. We also describe the site monitoring system that will allow an isolated SONG and 50BiN node to operate safely in an automated mode.