Photometric Precision of a Si:As Impurity Band Conduction Mid-infrared Detector and Application to Transit Spectroscopy
Photometric Precision of a Si:As Impurity Band Conduction Mid-infrared Detector and Application to Transit Spectroscopy
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DOI：
10.1088/1538-3873/ab42f1
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发表时间：
2019-12-01
影响因子：
3.5
通讯作者：
Ennico, Kimberly
中科院分区：
文献类型：
--
作者：
Matsuo, Taro;Greene, Thomas P.;Ennico, Kimberly
凌日光谱学是在中红外（3？30年？m）波长在未来20年。斯皮策空间望远镜在观测凌日行星时已经达到了中等程度的中红外测光精度，但中红外探测器本身的内在测光稳定性在科学或技术文献中还没有报道。在这里，我们评估的测光精度的詹姆斯韦伯太空望远镜中红外仪器原型中红外硅：作为杂质带传导探测器，使用泛光照明下采取的时间序列数据。这些测光精度的测量进行了超过？10小时，代表观测系外行星凌日所需的时间。在选择具有10&xfffd;&x5e0;10像素的大小的多个子区域并且补偿由我们的暖检测器控制电子器件针对所选择的子区域引起的增益变化之后，我们发现，由于由我们的暖检测器控制电子器件引起的增益变化，在高共添加信号水平下，光度精度被限制为26.3ppm。经过增益漂移校正后，系统的测光精度提高到12.8ppm。我们还将光度精度转换为预期的分光光度精度（即，波长之间的相对光度精度），假设在过境观测中使用优化的致密光瞳摄谱仪。我们发现，当用于过境观测时，优化的致密光瞳摄谱仪的分光光度精度预计将通过每个光谱分辨率元件的像素数的平方根来提高。在高的共加信号电平下，总噪声可以降低到7 ppm，这比受泊松噪声和读出噪声限制的理想性能大1.3倍。隐藏在模拟透射光谱后面的系统噪声为1.7ppm。
Transit spectroscopy is the most promising path toward characterizing nearby terrestrial planets at mid-infrared (3?30 ?m) wavelengths in the next 20 yr. The Spitzer Space telescope has achieved moderately good mid-infrared photometric precision in observations of transiting planets, but the intrinsic photometric stability of mid-IR detectors themselves has not been reported in the scientific or technical literature. Here, we evaluated the photometric precision of a James Webb Space Telescope Mid-Infrared Instrument prototype mid-infrared Si:As impurity band conduction detector, using time-series data taken under flood illumination. These measurements of photometric precision were conducted over periods of ?10 hr, representative of the time required to observe an exoplanet transit. After selecting multiple sub-regions with a size of 10 & xfffd;& x5e0;10 pixels and compensating for a gain change caused by our warm detector control electronics for the selected sub-regions, we found that the photometric precision was limited to 26.3 ppm at high co-added signal levels due to a gain variation caused by our warm detector control electronics. The photometric precision was improved up to 12.8 ppm after correcting for the gain drift. We also translated the photometric precision to the expected spectro-photometric precision (i.e., relative photometric precision between wavelengths), assuming that an optimized densified pupil spectrograph is used in transit observations. We found that the spectro-photometric precision of an optimized densified pupil spectrograph when used in transit observations is expected to be improved by the square root of the number of pixels per a spectral resolution element. At the high co-added signal levels, the total noise could be reduced down to 7 ppm, which was larger by a factor of 1.3 than the ideal performance that was limited by the Poisson noise and readout noise. The systematic noise hidden behind the simulated transit spectroscopy was 1.7 ppm.