arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1601.02655astro-ph.IM
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适当的图像减影-最佳瞬态检测、photometry和假设检验

Proper image subtraction - optimal transient detection, photometry and hypothesis testing

Barak Zackay, Eran O. Ofek, Avishay Gal-Yam

摘要:

瞬态检测和流量测量通过图像减法站在时域天文学的基础。由于变化的观看条件,图像相减过程是不平凡的,并且现有的解决方案遭受各种问题。从基本的统计原理出发,我们开发了瞬态检测,通量测量和任何图像差异假设检验的最佳统计量。我们推导出一个封闭形式的统计量:(i)在数学上被证明是最佳的瞬态检测统计量的限制背景占主导地位的噪声;(ii)是数值稳定的;(iii)对于准确注册,充分采样的图像,不留下减法或反卷积伪影;(iv)允许自动瞬态检测的理论灵敏度限制,通过提供可靠的检测意义;(v)具有不相关的白噪声;(vi)对于差图像上的任何进一步的统计测试是足够的统计量,并且特别地,允许将粒子撞击和其他图像伪影与真实瞬态区分开;(vii)对于新图像和参考图像的交换是对称的;(viii)计算比一些流行的方法快至少一个数量级;(ix)易于实现。此外,我们提出了这种方法的扩展,使其具有弹性的注册错误,颜色折射错误,和任何噪声源,可以建模。此外,我们还证明了准备参考图像的最佳方法是Zackay \& Ofek(2015 b)中提出的适当的图像加和。我们证明了这种方法的模拟数据和实际观测的Palomar瞬态工厂数据发布2。我们在MATLAB和Python中提供了该算法的实现。

英文摘要:

Transient detection and flux measurement via image subtraction stand at the base of time domain astronomy. Due to the varying seeing conditions, the image subtraction process is non-trivial, and existing solutions suffer from a variety of problems. Starting from basic statistical principles, we develop the optimal statistic for transient detection, flux measurement and any image-difference hypothesis testing. We derive a closed-form statistic that: (i) Is mathematically proven to be the optimal transient detection statistic in the limit of background-dominated noise; (ii) Is numerically stable; (iii) For accurately registered, adequately sampled images, does not leave subtraction or deconvolution artifacts; (iv) Allows automatic transient detection to the theoretical sensitivity limit by providing credible detection significance; (v) Has uncorrelated white noise; (vi) Is a sufficient statistic for any further statistical test on the difference image, and in particular, allows to distinguish particle hits and other image artifacts from real transients; (vii) Is symmetric to the exchange of the new and reference images; (viii) Is at least an order of magnitude faster to compute than some popular methods; and (ix) Is straightforward to implement. Furthermore, we present extensions of this method that make it resilient to registration errors, color-refraction errors, and any noise source that can be modelled. In addition, we show that the optimal way to prepare a reference image is the proper image coaddition presented in Zackay \& Ofek (2015b). We demonstrate this method on simulated data and real observations from the Palomar Transient Factory data release 2. We provide an implementation of this algorithm in MATLAB and Python.

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