Analysis of the COS/NUV Extraction Box Heights
Analysis of the COS/NUV Extraction Box Heights
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COS/NUV 提取箱高度分析
DOI：
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发表时间：
2017
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影响因子：
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通讯作者：
P. Sonnentrucker
中科院分区：
文献类型：
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作者：
E. M. Snyder;P. Sonnentrucker
本文提出了一种提取箱高度（EBHs）的诊断方法，用于提取哈勃太空望远镜上宇宙起源光谱仪（COS）拍摄的NUV光谱数据。本研究的动机是观测计划期间COS曝光时间计算器使用的EBH（8像素）与COS校准管道（CALCOS）在最终光谱创建期间（57像素）之间存在差异。在这篇仪器科学报告中，我们研究了降低EBH对许多不同目标的calcos还原光谱的净计数和信噪比的影响。我们发现，为了避免提取光谱时的计数损失，EBH不应小于37−43像素。对于目标较暗的数据集，降低EBH不能显著提高信噪比，并且可能对较亮目标的通量精度产生负面影响。分析表明，EBH的优化具有很强的目标依赖性。因此，CALCOS管道使用的EBH保持在57像素的保守值。我们还为希望对其数据执行自定义提取的用户提供详细说明。
We present a diagnostic test of the extraction box heights (EBHs) used when extracting NUV spectroscopic data taken by the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope. This study was motivated by a discrepancy between the EBH used by the COS Exposure Time Calculator during observation planning (8 pixels) and the COS calibration pipeline (CALCOS) during the creation of the final spectra (57 pixels). In this Instrument Science Report, we study the effects of decreasing the EBH on the net counts and signal-to-noise ratio for CALCOS-reduced spectra of many different targets. We find that the EBH should not be smaller than 37− 43 pixels to avoid count loss when extracting the spectra. Reducing the EBH does not significantly improve the signal-to-noise ratio for datasets with faint targets, and can possibly have a negative effect on the flux accuracy of brighter targets. The analysis shows that optimization of the EBH is heavily target-dependent. As a result, the EBH used by the CALCOS pipeline is maintained at the conservative value of 57 pixels. We also provide detailed instructions for users who wish to perform a custom extraction for their data.