PSF modelling for very wide-field CCD astronomy
PSF modelling for very wide-field CCD astronomy
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DOI：
10.1051/0004-6361/201219230
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发表时间：
2013-03-01
影响因子：
6.5
通讯作者：
Zarnecki, A. F.
中科院分区：
文献类型：
--
作者：
Piotrowski, L. W.;Batsch, T.;Zarnecki, A. F.
语境。探测伽马射线暴光学对应物的可能方法之一需要监测天空的大部分区域。近年来，这个想法获得了一些工具性的支持，例如“Pi of the Sky”项目。 “Pi of the Sky”装置的广阔天空覆盖范围是通过使用带有广角镜头（20 度 x 20 度视场）的相机实现的。这种光学器件会引起点扩散函数 (PSF) 的显着变形，并随着距框架中心的距离而增加。变形的 PSF 会导致数据分析中出现额外的不确定性。我们的目标是创建一个描述光学天文学中高度变形的PSF的模型，从而减少图像变形引起的不确定性。方法。对 PSF、像素灵敏度和像素响应函数进行了详细的实验室测量。这些数据用于创建有效的高质量 PSF 多项式模型。最后，根据真实天空数据对模型进行了调整并进行了应用测试。结果。我们开发了一种 PSF 模型，可以在我们的宽视场实验中准确地描述甚至非常变形的恒星。该模型适用于任何其他具有类似图像变形的实验，只需简单调整其参数即可。将此模型应用于天体测量程序可比标准方法得到显着改进，而使用该模型执行的基本光度测量精度可与优化孔径算法的结果相媲美。此外，该模型还用于搜索微弱信号，即可能的伽马射线爆发光学前兆，显示出非常有希望的结果。结论。 PSF 函数的精确建模显着提高了天体测量精度，并增强了具有透镜光学器件的宽视场系统的发现潜力。
Context. One of the possible approaches to detecting optical counterparts of GRBs requires monitoring large parts of the sky. This idea has gained some instrumental support in recent years, such as with the "Pi of the Sky" project. The broad sky coverage of the "Pi of the Sky" apparatus results from using cameras with wide-angle lenses (20 degrees x 20 degrees field of view). Optics of this kind introduce significant deformations of the point spread function (PSF), increasing with the distance from the frame centre. A deformed PSF results in additional uncertainties in data analysis.Aims. Our aim was to create a model describing highly deformed PSF in optical astronomy, allowing uncertainties caused by image deformations to be reduced.Methods. Detailed laboratory measurements of PSF, pixel sensitivity, and pixel response functions were performed. These data were used to create an effective high quality polynomial model of the PSF. Finally, tuning the model and tests in applications to the real sky data were performed.Results. We have developed a PSF model that accurately describes even very deformed stars in our wide-field experiment. The model is suitable for use in any other experiment with similar image deformation, with a simple tuning of its parameters. Applying this model to astrometric procedures results in a significant improvement over standard methods, while basic photometry precision performed with the model is comparable to the results of an optimised aperture algorithm. Additionally, the model was used to search for a weak signal - namely a possible gamma ray burst optical precursor - showing very promising results.Conclusions. Precise modelling of the PSF function significantly improves the astrometric precision and enhances the discovery potential of a wide-field system with lens optics.