Conjugate Plane Photometry: Reducing Scintillation Noise in Ground-Based Astronomical Photometry

共轭平面光度测定：减少地基天文光度测定中的闪烁噪声

• 批准号: ST/J001236/1
• 负责人: Richard Wilson
• 金额: $ 28.99万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FJ001236%2F1
• 关键词: Conjugate; Plane; Photometry; Reducing; Scintillation

Scintillation is the phenomenon that we observe as the 'twinkling' of stars. It results from the optical effect of high-altitude turbulence in the Earth's atmosphere which, at any given time, diverts a fraction of the starlight into or out of the receiving aperture (e.g. telescope or eye) at the ground. This results in a rapid fluctuation of the total light intensity observed. For a large telescope, these fluctuations are averaged over the aperture area, so that the degree of 'twinkling' seen through a large telescope is much less than for the naked eye. However, for some types of telescope observations, these small residual intensity fluctuations are of critical importance: in particular for high-speed measurements of rapidly changing phenomena, such as the reduction in the measured light intensity which results when an extra-solar planet passes behind its parent star, as seen from Earth. The dip in brightness resulting from such an exoplanet eclipse is usually very small (much less than 0.1%), since the planet contributes only a small fraction of the total light from the system. However, accurate observations of such eclipses can provide a wealth of information about the planet and its orbit around the parent star. For observations from the ground, scintillation noise limits the accuracy with which the eclipse 'light curve' can be determined so that, until now, the best data have typically been obtained with space-based telescopes, above the effects of the Earth's atmosphere. Here we propose to develop a new technique, known as 'Conjugate Plane Photometry' to effectively 'un-twinkle' photometric observations with ground-based telescopes. In this method, the high-altitude turbulent layer is focused onto a circular mask within the optical system of the instrument. The mask aperture is slightly smaller than the diameter of the telescope itself. This mask rejects that part of the starlight, close to the edge of the telescope aperture, that could have been diverted by the high turbulence into or out of the telescope, causing scintillation. The size of intensity fluctuations due to scintillation are then greatly reduced, so that more accurate photometric observations become possible with ground-based telescopes. Our proposed research seeks to demonstrate the full potential of the conjugate-plane photometry technique by developing a prototype instrument and deploying it on a large telescope. The ultimate goal of the work will be to demonstrate that photometric observations of phenomena such as exoplanet eclipses can be made from the ground with an accuracy approaching that which is possible with space-based telescopes.

闪烁是我们观察到的星星“闪烁”的现象。它是由地球大气层中高空湍流的光学效应引起的，在任何给定的时间，都会将一部分星光转移到地面的接收孔径（例如望远镜或眼睛）。这导致观察到的总光强度的快速波动。对于大型望远镜来说，这些波动在孔径范围内是平均的，因此通过大型望远镜看到的“闪烁”程度远小于肉眼。然而，对于某些类型的望远镜观测，这些微小的残余强度波动至关重要：特别是对于快速变化现象的高速测量，例如当太阳系外行星从其母星星后面经过时，从地球上看到的测量光强度减少。这样的系外行星食造成的亮度下降通常非常小（远小于0.1%），因为行星只贡献了系统总光线的一小部分。然而，对这种日食的精确观测可以提供关于行星及其围绕母星星的轨道的丰富信息。对于地面观测，闪烁噪声限制了日食“光变曲线”的准确性，因此，到目前为止，最好的数据通常是通过太空望远镜获得的，高于地球大气层的影响。在这里，我们建议开发一种新的技术，被称为“共轭平面测光”，以有效地“不闪烁”的光度观测与地面望远镜。在这种方法中，高空湍流层被聚焦到仪器光学系统内的圆形掩模上。掩模孔径比望远镜本身的直径略小。该掩模拒绝了靠近望远镜孔径边缘的那部分星光，这些星光可能会被高湍流转移到望远镜中或从望远镜中转移出来，从而导致闪烁。由于闪烁引起的强度波动的大小大大减小，因此可以用地面望远镜进行更精确的光度观测。我们提出的研究旨在通过开发原型仪器并将其部署在大型望远镜上来展示共轭平面测光技术的全部潜力。这项工作的最终目标将是证明，可以从地面对系外行星日食等现象进行光度观测，其精度接近天基望远镜。

项目成果

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

• DOI: 10.1093/mnras/stw2685
• 发表时间: 2017-01
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: J. Osborn;T. Butterley;M. Townson;A. Reeves;T. Morris;R. Wilson

Hunting For Eclipses: High Speed Observations of Cataclysmic Variables

寻找日食：灾难性变量的高速观测

• DOI: 10.48550/arxiv.1611.07885
• 发表时间: 2016
• 作者: Hardy L

Long-Term Photometry of IC 348 with the YETI Network

使用 YETI 网络对 IC 348 进行长期光度测量

• DOI: 10.48550/arxiv.1607.06322
• 发表时间: 2016
• 作者: Fritzewski D

Flares, wind and nebulae: the 2015 December mini-outburst of V404 Cygni

耀斑、风和星云：2015 年 12 月天鹅座 V404 的小型爆发

• DOI: 10.1093/mnrasl/slw222
• 发表时间: 2016
• 期刊: Letters
• 作者: Mu Noz-Darias T

Stereo-SCIDAR: optical turbulence profiling with high sensitivity using a modified SCIDAR instrument

• DOI: 10.1093/mnras/stt2150
• 发表时间: 2013-12
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: H. Shepherd;J. Osborn;R. Wilson;T. Butterley;R. Avila;V. Dhillon;T. Morris