Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor
Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor
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JWST NIRSpec 实验室时间序列分析：表征系统学、恢复系外行星凌日光谱以及限制本底噪声
DOI：
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发表时间：
2022
影响因子：
7.9
通讯作者：
Ashley Wang
中科院分区：
文献类型：
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作者：
Z. Rustamkulov;D. Sing;Rongrong Liu;Ashley Wang
詹姆斯·韦伯太空望远镜 (JWST) 的 NIRSpec 仪器将揭示从温带类地世界到超热木星等多种行星类型的系外行星大气层的性质。特别是，0.6–5.3 μm PRISM 模式特别适合跨越许多重要光谱特征的高效光谱系外行星观测。我们从 JWST 用户的角度分析实验室测量的 NIRSpec PRISM 模式明亮物体时间序列观测，以了解仪器性能和探测器特性。我们通过对实验室测量的数据进行注入恢复测试来量化真实仪器抖动、漂移、像素内灵敏度变化和 1/f 噪声对测量透射光谱的影响，从而创建两个真实的凌日系外行星时间序列观测。通过同时拟合时间序列系统和注入的凌日，我们可以获得更真实的凌日深度不确定性，其中考虑了目前传统曝光时间计算器尚未建模的噪声源。我们发现，与像素内灵敏度变化和点扩散函数运动相关的系统噪声源在几百 ppm 水平的数据中很明显，但可以使用具有检测器位置的低阶多项式有效地消除趋势。我们恢复了 GJ 436 b 和 TRAPPIST-1 d 的注入光谱特征，并将探测器本底噪声设置为 3σ 上限，即 14 ppm。我们发现本底噪声在 1.7σ 水平上与 <10 ppm 一致，这对于未来对具有微弱大气特征的挑战性目标的观测来说是个好兆头。
The James Webb Space Telescope’s (JWST) NIRSpec instrument will unveil the nature of exoplanet atmospheres across the wealth of planet types, from temperate terrestrial worlds to ultrahot Jupiters. In particular, the 0.6–5.3 μm PRISM mode is especially well suited for efficient spectroscopic exoplanet observations spanning a number of important spectral features. We analyze a lab-measured NIRSpec PRISM mode Bright Object Time Series observation from the perspective of a JWST user to understand the instrument performance and detector properties. We create two realistic transiting exoplanet time-series observations by performing injection-recovery tests on the lab-measured data to quantify the effects of real instrument jitter, drift, intrapixel sensitivity variations, and 1/f noise on measured transmission spectra. By fitting the time-series systematics simultaneously with the injected transit, we can obtain more realistic transit-depth uncertainties that take into account noise sources that are currently not modeled by traditional exposure time calculators. We find that sources of systematic noise related to intrapixel sensitivity variations and point-spread function motions are apparent in the data at the level of a few hundred ppm but can be effectively detrended using a low-order polynomial with detector position. We recover the injected spectral features of GJ 436 b and TRAPPIST-1 d and place a 3σ upper limit on the detector noise floor of 14 ppm. We find that the noise floor is consistent with <10 ppm at the 1.7σ level, which bodes well for future observations of challenging targets with faint atmospheric signatures.
DOI：
10.3847/1538-3881/ab364d
发表时间：
2019-06
期刊：
The Astronomical Journal
影响因子：
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作者：
J. Winters;A. Medina;J. Irwin;D. Charbonneau;N. Astudillo-Defru;E. Horch;J. Eastman;E. Vrijmoet-E.-Vrijmoe
通讯作者：
J. Winters;A. Medina;J. Irwin;D. Charbonneau;N. Astudillo-Defru;E. Horch;J. Eastman;E. Vrijmoet-E.-Vrijmoe
DOI：
10.3847/2041-8213/aafb7a
发表时间：
2018-09
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
R. Vanderspek;Chelsea X. Huang;A. Vanderburg;G. Ricker;D. Latham;S. Seager;J. Winn;J. Jenkins
通讯作者：
R. Vanderspek;Chelsea X. Huang;A. Vanderburg;G. Ricker;D. Latham;S. Seager;J. Winn;J. Jenkins