Characterization and correction of charge-induced pixel shifts in DECam
Characterization and correction of charge-induced pixel shifts in DECam
复制标题
DECam 中电荷引起的像素偏移的表征和校正
DOI：
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复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Stella Seitz
中科院分区：
文献类型：
--
作者：
Daniel Gruen;Gary M. Bernstein;Mike Jarvis;Barnaby Rowe;V. Vikram;A. Plazas;Stella Seitz
CCD中的电荷与已经累积的电荷分布的相互作用导致点扩散函数的通量依赖性（观察到的尺寸随着通量的增加，也称为更亮/更胖效应）和平坦场中的泊松噪声的像素到像素相关性。我们在暗能量相机（DECam）中描述了这些效应，其中有效像素边界的电荷相关漂移，即Antilogus等人（2014）模型，我们将其拟合到平场{Poissonian}噪声相关性的测量值。后者近似地以幂律r-2.5随着像素间隔r而下降，除了沿着行和列的直接相邻者中的不对称性之外是各向同性的，在时间上是稳定的，并且弱地依赖于波长。它们显示了与硅电阻率相关的20%水平的芯片与芯片之间的变化。该模型预测的电荷位移导致形状测量偏差，主要是由于它们对明亮恒星的影响，超过了弱透镜科学的要求。我们测量了星星图像的通量依赖性，并表明在图像处理过程中，通过在像素级上施加反向电荷移位，可以减轻这种影响。然而，恒星大小的差异仍然显着，由于残差在更大的距离质心。
Interaction of charges in CCDs with the already accumulated charge distribution causes both a flux dependence of the point-spread function (an increase of observed size with flux, also known as the brighter/fatter effect) and pixel-to-pixel correlations of the {Poissonian} noise in flat fields. We describe these effects in the Dark Energy Camera (DECam) with charge dependent shifts of effective pixel borders, i.e. the Antilogus et al. (2014) model, which we fit to measurements of flat-field {Poissonian} noise correlations. The latter fall off approximately as a power-law r−2.5 with pixel separation r, are isotropic except for an asymmetry in the direct neighbors along rows and columns, are stable in time, and are weakly dependent on wavelength. They show variations from chip to chip at the 20% level that correlate with the silicon resistivity. The charge shifts predicted by the model cause biased shape measurements, primarily due to their effect on bright stars, at levels exceeding weak lensing science requirements. We measure the flux dependence of star images and show that the effect can be mitigated by applying the reverse charge shifts at the pixel level during image processing. Differences in stellar size, however, remain significant due to residuals at larger distance from the centroid.
暗能量勘测相机（DECam）项目的现状
DOI：
10.1117/12.926216
发表时间：
2012
期刊：
--
影响因子：
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作者：
Flaugher B
通讯作者：
Flaugher B
DOI：
10.1111/j.1365-2966.2006.10198.x
发表时间：
2006-05-21
影响因子：
4.8
作者：
Heymans, C;Van Waerbeke, L;Wittman, D
通讯作者：
Wittman, D