4GREAT is an extension of the German receiver for astronomy at terahertz frequencies (GREAT) operated aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectrometer comprises four different detector bands and their associated subsystems for simultaneous and fully independent science operation. All detector beams are coaligned on the sky. The frequency bands of 4GREAT cover 491-635, 890-1090, 1240-1525, and 2490-2590 GHz, respectively. This article presents the design and characterization of the instrument, and its in-flight performance. The first light of 4GREAT was on June 2018. It has been offered to the interested SOFIA communities starting with observing cycle 6.

中文翻译：

---

4GREAT——用于高分辨率机载太赫兹光谱的四色接收器


4GREAT 是在平流层红外天文台 (SOFIA) 上运行的德国太赫兹频率天文学接收器 (GREAT) 的扩展。该光谱仪由四个不同的检测器带及其相关子系统组成，用于同时且完全独立的科学操作。所有探测器光束都在天空上对齐。 4GREAT的频段分别覆盖491-635、890-1090、1240-1525和2490-2590 GHz。本文介绍了该仪器的设计和特性及其飞行性能。 4GREAT 的首次亮相于 2018 年 6 月。它已从观测周期 6 开始提供给感兴趣的 SOFIA 社区。