AI 中文总结
研究南希·格雷斯·罗曼太空望远镜广域仪器对亮点状源的饱和响应与余辉特性。通过热真空测试，利用射线锥刺激望远镜模拟器投射不同亮度点状源到探测器，分析其饱和区域及余辉情况，为探测器响应研究及罗曼科学做准备。
AI 中文摘要
南希·格雷斯·罗曼太空望远镜的广域仪器（WFI）在其核心社区调查中会观测数十万颗亮星，尤其是在银心时域调查（GBTDS）的密集恒星场中。比约17等亮的源在典型调查曝光中会使WFI探测器像素饱和，最亮的恒星会使大像素区域深度饱和并可能产生影响后续观测的余辉信号。之前的探测器表征未探索深点状源饱和情况。我们在科罗拉多州博尔德市BAE空间与任务系统公司进行的WFI第二次热真空测试（TVAC2）期间开展了亮星饱和测试。利用射线锥刺激（SORC）望远镜模拟器，在约170秒曝光中，通过F146滤光片将九个聚焦点状源投射到两个传感器芯片组件（SCA）上，通量经调整以近似约4至约18等的恒星亮度。我们展示了对这些探测器饱和响应和余辉特性的分析。我们发现，约4等源的饱和区域在光照约170秒后直径增长到约150像素，而约12等源为约15像素。与扩展饱和前沿相邻的像素表现出明显的非线性行为，与饱和相邻像素的电荷泄漏一致。对于余辉，我们发现照明后首次暗曝光中的中值信号在约4至约17等的源亮度范围内大致一致，且余辉在约20分钟内衰减到探测器背景水平（$\lesssim$0.05 e$^{-}$ s$^{-1}$），与同一TVAC2测试中的平场余辉测量结果一致。这些飞行前表征结果有助于科学界了解WFI探测器响应，为罗曼科学做准备。
英文摘要
The Nancy Grace Roman Space Telescope's Wide Field Instrument (WFI) will observe hundreds of thousands of bright stars across its Core Community Surveys, particularly in the dense stellar fields of the Galactic Bulge Time Domain Survey (GBTDS). Sources brighter than ~17th magnitude will saturate WFI detector pixels in typical survey exposures, with the brightest stars deeply saturating large pixel regions and potentially producing persistence signals that may impact subsequent observations. Prior detector characterization did not explore the regime of deep point source saturation. To address this gap, we conducted a bright star saturation test during WFI's second Thermal Vacuum test campaign (TVAC2) at BAE Space & Mission Systems in Boulder, CO. Using the Stimulus of Ray Cones (SORC) telescope simulator, we projected nine in-focus point sources through the F146 filter onto two Sensor Chip Assemblies (SCAs), with fluxes tuned to approximate stellar magnitudes ranging from ~4 to ~18 in ~170 s exposures. We present analyses of the saturation response and persistence properties of these detectors. We find that the saturated region of a ~4 mag source grows to ~150 pixels in diameter after ~170 s of illumination, compared to ~15 pixels for a ~12 mag source. Pixels adjacent to the expanding saturation front exhibit pronounced non-linear behavior consistent with charge leakage from saturated neighbors. For persistence, we find that the median signal in the first post-illumination dark exposure is broadly consistent across source magnitudes spanning ~4 to ~17, and that persistence decays to detector background levels ($\lesssim$0.05 e$^{-}$ s$^{-1}$) within approximately 20 minutes, consistent with flat field persistence measurements from the same TVAC2 campaign. These pre-flight characterization results inform community understanding of WFI detector response to prepare for Roman science.
Comments36 pages, 36 figures, submitted to PASP, abstract abridged to meet arXiv requirements, Zenodo link to data products forthcoming, comments welcome!
