Attstbas

Attstbas refers to the Advanced Thermal Spectral Saturation Banding Array System, an instrument developed for high‑resolution spectroscopic studies of stellar atmospheres. The system was first proposed in 2017 by a collaboration of the European Southern Observatory and the Max Planck Institute for Astronomy, and its prototypes were installed at the La Silla Observatory in 2021. Attstbas combines a cryogenically cooled heterodyne receiver array with a tunable Fabry‑Pérot etalon, enabling simultaneous coverage of key spectral lines from the near‑infrared to the mid‑infrared with a resolving power exceeding one‑hundred‑thousand.

The array consists of sixteen independent detector channels, each optimized for a distinct wavelength band between 0.8 and 5.0 micrometres. A key innovation is the use of titanium‑doped sapphire mirrors, which reduce thermal loading and allow the instrument to maintain a consistent baseline temperature of 4 Kelvin over observation periods of up to eight hours. Attstbas also incorporates active vibration isolation and a digital adaptive optics subsystem, which corrects for atmospheric distortion in real time and improves spectral fidelity.

Scientific programs currently underway include studies of exoplanetary atmospheres, precise radial‑velocity measurements for exoplanet detection, and investigations of stellar chemical composition variations across the Milky Way. Early results have led to the identification of minor isotopic signatures in red giant stars, offering insights into nucleosynthetic processes. The instrument’s design and performance have been documented in peer‑reviewed journals such as the Astronomical Journal and the Journal of Astrophysics and Astronomy. Future upgrades plan to extend the wavelength coverage to the far‑infrared and to implement machine‑learning algorithms for automated spectral line identification.