STIS CCD的波长校准精度：管道更新与用户指南
Wavelength Calibration Accuracy Across the STIS CCD: Pipeline Update and User Guidance
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中文总结 AI 辅助
该研究针对STIS CCD的波长校准精度问题，更新了calstis4管道并提供Jupyter Notebook，使MAST中97%以上的STIS数据集的光谱一致性得到改善，同时分析了例外情况及对科学结果的影响。
中文摘要 AI 辅助
我们研究了STIS CCD光谱的波长校准精度与探测器位置的关系，重点关注E1/E2伪孔径。将测量的灯线中心与实验室波长进行比较后发现，虽然标准calstis解决方案在探测器中心是稳定的，但在CCD边缘存在显著偏移，且随时间增加。我们使用了calstis的测试版本，其中波长校准步骤采用了行选择互相关，这提升了边缘提取的波长校准精度。受这些结果启发，我们对calstis4进行了更新，该更新会对使用E1/E2伪孔径的观测应用行选择波校准程序，同时为标准提取保留原有的标准程序。更新后的管道随后被用于重新处理MAST中的整个STIS档案。验证测试确认，MAST档案中超过97%的数据集，其标准光谱与E1/E2光谱的一致性得到改善，且无显著副作用。主要例外是大部分G230MB以及少数G230LB和G430M数据集，这些数据中CCD边缘的低信噪比使得灯线更难检测，且宇宙射线残差可能主导互相关，进而导致错误的波长偏移。我们还提供了一个Jupyter Notebook，以便在互相关失败、针对E1/E2以外位置的提取或沿狭缝的多次提取时进行类似校正。最后，我们讨论了波长校准精度对科学结果的潜在影响。
英文摘要
We investigate the wavelength calibration accuracy of STIS CCD spectra as a function of detector position, focusing on the E1/E2 pseudo-apertures. Comparison between measured lamp line centroids and laboratory wavelengths shows that, while the standard calstis solution is stable at the detector center, significant offsets are present toward the CCD edges and increase with time. We used a test version of calstis in which the wavelength calibration step employs a row-selected cross-correlation, leading to improved wavelength calibration accuracy for edge extractions. Motivated by these results, we implemented an update to calstis4 that applies a row-selected wavecal procedure to observations taken with the E1/E2 pseudo-apertures, while preserving the standard procedure for nominal extractions. The updated pipeline was then used to reprocess the entire STIS archive in MAST. Validation tests confirm improved agreement between nominal and E1/E2 spectra without significant side effects for more than 97% of the datasets in the MAST archive. The main exceptions are the majority of G230MB and a few G230LB and G430M datasets, where the lower signal-to-noise at the CCD edge makes the lamp lines harder to detect and cosmic-ray residuals can dominate the cross-correlation, leading to incorrect wavelength shifts. A Jupyter Notebook is also provided to enable similar corrections in case the cross-correlation fails, for extractions at positions other than E1/E2, or for multiple extractions along the slit. Finally, we discuss the potential impact of the wavelength calibration accuracy on science results.
