Abstract
In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensors.
Highlights
In an image of the sky taken to observe either stars or orbital objectsthe object of interest appears convolved with the structure and motion of the source, the emission process, the atmosphere, the telescope and detector interaction, etc
Since the discovery in 1990 of a severe problem of spherical aberration in the mirror of the Hubble Space Telescope (HST) a substantial amount of work has been done in this field directed towards optical and near-IR astronomy, covering different types of data noise and proposing dozens of algorithms
We will focus our study into a more sophisticated algorithm—the Adaptive Wavelet-decomposition-based Maximum Likelihood (AWMLE) method [5,13], which shows a better noise amplification control and asymptotically convergence, and it is Point Spread Function (PSF)-invariant like the majority of deconvolution algorithms that deal with large amount of data
Summary
In an image of the sky taken to observe either stars or orbital objects (satellites, space debris, etc.). Point Spread Function (PSF), of the order of one arc second diameter Such light distribution is in most cases well represented by a Gaussian-like pattern but it can vary along the image. If the object of interest is orbiting the Earth, the main effect is the convolution with its motion with respect to the stars In this case, if the frame was taken tracking the sky, a point-like moving object appears in the images as a trail. Earth sidereal motion and on the exposure time In both cases, the result of the convolution is to spread the light of the star or the moving object over several pixels of the image sensor decreasing the ability to be detected and the accuracy of the determination of its position. Since the discovery in 1990 of a severe problem of spherical aberration in the mirror of the Hubble Space Telescope (HST) a substantial amount of work has been done in this field directed towards optical and near-IR astronomy (with applications in other fields), covering different types of data noise and proposing dozens of algorithms
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