AI 中文总结
GroundBIRD实验旨在测量CMB大角度尺度各向异性以约束再电离光学深度。通过对木星重复观测，得出首个天空响应度校准模型，建立并验证校准方法，表征探测器响应度与PWV关系，为扩展校准方法至整个焦平面奠定基础。
AI 中文摘要
GroundBIRD是位于特内里费岛天文台（西班牙，海拔约2400米）的宇宙微波背景（CMB）实验，旨在测量大角度尺度强度和极化各向异性（$\ell \gtrsim 6$至$\ell \sim 300$）以约束再电离光学深度$\tau$。该仪器采用固定仰角70度的快速旋转望远镜，配备161个微透镜耦合动态电感探测器（KIDs）。我们展示了首个基于天空的GroundBIRD响应度校准模型，通过对木星的重复观测得出。分析建立并验证了该探测器子集的校准方法，首次对探测器响应度随可降水量水汽（PWV）的函数进行了经验性表征。与月球观测的比较揭示了与不同光学负载条件相关的不同探测器工作模式。基于木星的校准在典型观测条件下精度优于20%，在一个月时间尺度上相对稳定性优于20%。这些结果为将校准方法扩展到整个GroundBIRD焦平面奠定了基础。
英文摘要
GroundBIRD is a cosmic microwave background (CMB) experiment located at the Teide Observatory (altitude $\sim2400$ m, Spain) designed to measure large-angular-scale intensity and polarization anisotropies ($\ell \gtrsim 6$ to $\ell \sim 300$) to constrain the reionization optical depth, $τ$. The instrument employs a rapidly rotating telescope with a fixed elevation of $70$ deg and is equipped with 161 lenslet-coupled kinetic inductance detectors (KIDs): 138 at 145 GHz for CMB observations and 23 at 220 GHz for thermal dust characterization, all operated at $\sim280$ mK. This scan strategy provides daily coverage of $\sim$40% of the Northern Hemisphere sky. We present the first on-sky responsivity calibration model for GroundBIRD, derived from repeated observations of Jupiter using the twelve most stable KIDs from GroundBIRD array 6 (GB06). The analysis establishes and validates a calibration methodology for this detector subset while providing the first empirical characterization of detector responsivity as a function of precipitable water vapor (PWV). We find that the responsivity decreases by approximately 30% across the sampled PWV range and is well described by a linear PWV-dependent model. Comparison with Moon observations reveals distinct detector operating regimes associated with different optical loading conditions. The Jupiter-based calibration achieves better than 20% precision under typical observing conditions and better than 20% relative stability over a one-month timescale. These results establish the basis for extending the calibration methodology to the full GroundBIRD focal plane.
CommentsTo appear in Proceedings of SPIE, Astronomical Telescopes + Instrumentation 2026. 13 pages, 6 figures, 1 table
