The brighter-fatter effect and pixel correlations in CCD sensors

By P. Antilogus, P. Astier, Peter Doherty, A. Guyonnet, N. Regnault. 2014

134 citations recorded by the source corpus.

We present evidence that spots imaged using astronomical CCDs do not exactly scale with flux: bright spots tend to be broader than faint ones, using the same illumination pattern. We measure that the linear size of spots or stars, of typical size 3 to 4 pixels FWHM, increase linearly with their flux by up to 2 % over the full CCD dynamic range. This brighter-fatter effect affects both deep-depleted and thinned CCD sensors. We propose that this effect is a direct consequence of the distortions of the drift electric field sourced by charges accumulated within the CCD during the exposure and experienced by forthcoming light-induced charges in the same exposure. The pixel boundaries then become slightly dynamical: overfilled pixels become increasingly smaller than their neighbors, so that bright star sizes, measured in number of pixels, appear larger than those of faint stars. This interpretation of the brighter-fatter effect implies that pixels in flat-fields should exhibit statistical correlations, sourced by Poisson fluctuations, that we indeed directly detect. We propose to use the measured correlations in flat-fields to derive how pixel boundaries shift under the influence of a given charge pattern, which allows us in turn to predict how star shapes evolve with flux. We show that, within the precision of our tests, we are able to quantitatively relate the correlations of flat-field pixels and the broadening of stars with flux. This physical model of the brighter-fatter effect also explains the commonly observed phenomenon that the spatial variance of CCD flat-fields increases less rapidly than their average.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/b280030e19c770d1bd5e9d19c90c4be0e83e7260

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Citations in the corpus

Galaxy Alignments: Observations and Impact on Cosmology (2015, background): “This is less relevant for ground-based observations where the brighter sky fills the charge traps but other effects persist, including charge-induced pixel shifts (Gruen et al. 2015), the brighter/fatter effect for individual charge wells (Antilogus et al. 2014) and others.”
Gravitational lensing analysis of the Kilo-Degree Survey (2015, background): “The effect is due to the use of modern deep depletion CCDs in DECam (Antilogus et al. 2014), and is not expected to affect the thinned OmegaCAM detectors used for KiDS.”
The Hyper Suprime-Cam Software Pipeline (2017, background): “It has been recently observed for thick-depleted CCDs that the size and shape of the PSF depend upon the intensity of the source (Antilogus et al. 2014; Gruen et al. 2015).”
The Hyper Suprime-Cam SSP Survey: Overview and Survey Design (2017, background): “Four of the CCDs are used for guiding and eight for automatically monitoring focus, leaving 104 science detectors.”
The Dark Energy Survey Image Processing Pipeline (2018, unknown): “We also correct for CCD nonlinearity and the brighter-fatter effect (Antilogus et al. 2014, Gruen et al. 2015).”
The first-year shear catalog of the Subaru Hyper Suprime-Cam Subaru Strategic Program Survey (2017, methodology): “We also apply a correction to account for the brighter-fatter effect (Antilogus et al. 2014; Gruen et al. 2015).”
The DES Science Verification weak lensing shear catalogues (2015, background): “Another problem we addressed with regards to star selection is the so-called “brighter-fatter effect” (Antilogus et al. 2014; Guyonnet et al. 2015).”
Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology (2017, background): “…CCD was excluded from Y1 processing.8 The Y1A1 data processing did not correct for charge-induced pixel shifts (i.e., the “brighter-fatter” effect; Antilogus et al. 2014; Gruen et al. 2015), although corrections have been incorporated into more recent reductions of the DES data (Bernstein et…”
Dark Energy Survey Year 1 results: weak lensing shape catalogues (2017, background): “Most importantly, we remove all objects within 3 mag of the faintest saturated star in the same CCD exposure in order to avoid stars whose profiles are affected by the so-called ‘brighter-fatter effect’ (Antilogus et al. 2014; Gruen et al. 2015; Guyonnet et al. 2015) – see Section 3.2.”
GalSim: The modular galaxy image simulation toolkit (2014, background): “This can occur at low levels due to detector crosstalk (e.g. Moore et al., 2004; Antilogus et al., 2014) or the use of pixel-based corrections for charge transfer inefﬁciency (CTI, Massey et al. 2010), and it can be strikingly seen in images that have been created through the coaddition of two or…”
KiDS+VIKING-450: Cosmic shear tomography with optical and infrared data (2018, background): “For instance, the brighter-fatter effect (Antilogus et al. 2014) can affect the PSF sizes and ellipticities (as the effect is typically stronger in the parallel readout direction) for bright stars.”