An Efficient Local Block Sobolev Gradient and Laplacian Approach for Elimination of Atmospheric Turbulence

A long range observing systems can be sturdily affected by scintillations. These scintillations are caused by changes in atmospheric conditions. In recent years, various turbulence mitigation approaches for turbulence mitigation have been exhibiting a promising nature. In this paper, we propose an effectual method to alleviate the effects of atmospheric distortion on observed images and video sequences. These sequences are mainly affected through floating air turbulence which can severely degrade the image quality. The existing algorithms primarily focus on the removal of turbulence and provides a solution only for static scenes, where there is no moving entity (real motion). As in the traditional SGL algorithm, the updated frame is iteratively used to correct the turbulence. This approach reduces the turbulence effect. However, it imposes some artifacts on the real motion that blurs the object. The proposed method is an alteration of the existing Sobolev Gradient and Laplacian (SGL) algorithm to eliminate turbulence. It eliminates the ghost artifact formed on moving object in the existing approach. The proposed method alleviates turbulence without harming the moving objects in the scene. The method is demonstrated on significantly distorted sequences provided by OTIS and compared with the SGL technique. The information conveyed in the scene becomes clearly visible through the method on exclusion of turbulence. The proposed approach is evaluated using standard performance measures such as MSE, PSNR and SSIM. The evaluation results depict that the proposed method outperforms the existing state-of-the-art approaches for all three standard performance measures.

Exoplanet Ephemeris Maintenance using Ground- and Space-based Telescopes

<p>Ariel will require precise knowledge of the transit timings for all of its targets. However, the precision we have for each target will degrade significantly over the 8 years until launch, in some cases to the point where the error exceeds the duration of the transit itself. The knowledge of these transits would then be deemed “lost”. To counteract this, and in effect “reset the clock”, we aim to use the Telescope Live network of robotic telescopes to observe such targets. With 1000 targets and an average orbital period of the order of days, the size and usage of the network required needs to be quantified. Here we present results from simulations of these observations for a variety of telescope networks of varying sizes, the number of targets that can be successfully constrained, and the amount of observing time required to do so. From these results we can conclude that a ground-based telescope network containing as few as 2 telescopes of 0.6m aperture can constrain over 60% of the targets with transit depths observable from the ground. A fraction of these exoplanets are difficult to observe with ground-based telescopes as they either have transit depths too shallow to detect due to atmospheric distortion and/or their transit durations are comparable to the length of a night, reducing the probability of observable transits occurring. Such targets would benefit from supplementary observations from space-based observatories, as these do not suffer from either atmospheric distortion or limits on observing time due to Earth’s diurnal cycle.</p>