The Challan instrument is a solar full-disk imaging spectroscopic telescope planned to be installed at three sites with a 120-degree longitudinal difference, enabling continuous 24-hour observations of the Sun. It will take data every 2.5 min with a spatial resolution of 2−3′′ and a spectral resolving power (R) of >43,000 in Hα and Ca II 854.2 nm bands simultaneously. Challan is composed of two modules, each dedicated to a specific waveband. This modular design is beneficial in minimizing the scattered light and simplifying the structure and engineering. The primary scientific goal of Challan is to investigate solar flares and filament eruptions. It is also expected to detect small-scale events in the solar chromosphere. In 2025, Challan will be installed at the Big Bear Solar Observatory for test observational runs, followed by scientific runs in 2026.
@article{arxiv.2507.16294,
title = {Challan: Solar Full-disk Imaging-Spectroscopic Telescope using the Drift-Scanning Technique},
author = {Heesu Yang and Maria S. Madjarska and Donguk Song and Hannah Kwak and Sung-Hong Park and Eun-Kyung Lim and Sujin Kim and Su-Chan Bong and Yeon-Han Kim and Seonghwan Choi},
journal= {arXiv preprint arXiv:2507.16294},
year = {2025}
}