The gas pixel detector (GPD) is designed and developed for high-sensitivity astronomical X-ray polarimetry, which is a new window about to open in a few years. Due to the small mass, low power, and compact geometry of the GPD, we propose a CubeSat mission Polarimeter Light (PolarLight) to demonstrate and test the technology directly in space. There is no optics but a collimator to constrain the field of view to 2.3 degrees. Filled with pure dimethyl ether (DME) at 0.8 atm and sealed by a beryllium window of 100 μm thick, with a sensitive area of about 1.4 mm by 1.4 mm, PolarLight allows us to observe the brightest X-ray sources on the sky, with a count rate of, e.g., ∼0.2 counts s− 1 from the Crab nebula. The PolarLight is 1U in size and mounted in a 6U CubeSat, which was launched into a low Earth Sun-synchronous orbit on October 29, 2018, and is currently under test. More launches with improved designs are planned in 2019. These tests will help increase the technology readiness for future missions such as the enhanced X-ray Timing and Polarimetry (eXTP), better understand the orbital background, and may help constrain the physics with observations of the brightest objects.

中文翻译：

---

PolarLight：基于气体像素探测器的 CubeSat X 射线旋光仪

气体像素探测器（GPD）是为高灵敏度天文X射线偏振测量而设计和开发的，这是一个即将在几年内打开的新窗口。由于 GPD 质量小、功率低、几何结构紧凑，我们建议使用 CubeSat 任务偏振计光 (PolarLight) 直接在太空中演示和测试该技术。没有光学元件，只有一个准直器将视场限制在 2.3 度。充满 0.8 atm 的纯二甲醚 (DME) 并由 100 μm 厚的铍窗密封，敏感区域约为 1.4 mm x 1.4 mm，PolarLight 使我们能够观察天空中最亮的 X 射线源，具有蟹状星云的计数率约为 0.2 s-1。PolarLight 的尺寸为 1U，安装在 6U CubeSat 中，该卫星于 2018 年 10 月 29 日发射到近地太阳同步轨道，并且目前正在测试中。2019 年计划进行更多设计改进的发射。这些测试将有助于提高未来任务的技术准备，例如增强型 X 射线定时和偏振测量 (eXTP)，更好地了解轨道背景，并可能有助于通过观测约束物理学最亮的物体。