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We propose easy ways of correcting for the systematic errors caused by the photon noise and the pixelation effect in cosmic shear measurements. Our treatment of noise can reliably remove the noise contamination to the cosmic shear even when…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-16 Jun Zhang

In this paper a novel approach for de noising images corrupted by random valued impulses has been proposed. Noise suppression is done in two steps. The detection of noisy pixels is done using all neighbor directional weighted pixels (ANDWP)…

Computer Vision and Pattern Recognition · Computer Science 2012-06-04 J. K. Mandal , Somnath Mukhopadhyay

In order to improve image quality of projection in industrial applications, generally, a standard method is to increase the current or exposure time, which might cause overexposure of detector units in areas of thin objects or backgrounds.…

Image and Video Processing · Electrical Eng. & Systems 2024-12-10 Mengyu Sun , Dimeng Xia , Shusen Zhao , Weibin Zhang , Yaobin He

The Cherenkov Telescope Array Observatory (CTAO) is the next generation of ground-based observatories employing the imaging air Cherenkov technique for the study of very high energy gamma rays. The software Gammalearn proposes to apply Deep…

Instrumentation and Methods for Astrophysics · Physics 2025-02-12 Tom François , Justine Talpaert , Thomas Vuillaume

Imaging atmospheric Cherenkov telescopes (IACTs) detect gamma rays by measuring the Cherenkov light emitted by secondary particles in the air shower when the gamma rays hit the atmosphere. At low energies, the limited amount of Cherenkov…

A dramatic progress in the field of computer vision has been made in recent years by applying deep learning techniques. State-of-the-art performance in image recognition is thereby reached with Convolutional Neural Networks (CNNs). CNNs are…

Instrumentation and Methods for Astrophysics · Physics 2019-03-07 Tim Lukas Holch , Idan Shilon , Matthias Büchele , Tobias Fischer , Stefan Funk , Nils Groeger , David Jankowsky , Thomas Lohse , Ullrich Schwanke , Philipp Wagner

High energy cosmic-rays generate air showers when they enter Earth's atmosphere. Ground-based gamma-ray astronomy is possible using either direct detection of shower particles at mountain altitudes, or with arrays of imaging air-Cherenkov…

Instrumentation and Methods for Astrophysics · Physics 2025-02-27 Clara Escañuela Nieves , Felix Werner , Jim Hinton

Identification of Cherenkov light generated by muons has been suggested as a promising way to dramatically improve the background rejection power of Imaging Atmospheric Cherenkov Telescope (IACT) arrays at high energies. However, muon…

High Energy Astrophysical Phenomena · Physics 2022-12-13 Laura Olivera-Nieto , Helena X. Ren , Alison M. W. Mitchell , Vincent Marandon , Jim Hinton

This work is a methodical study on hybrid reconstruction techniques for hybrid imaging/timing Cherenkov observations. This type of hybrid array is to be realized at the gamma-observatory TAIGA intended for very high energy gamma-ray…

Instrumentation and Methods for Astrophysics · Physics 2018-08-29 E. B. Postnikov , A. A. Grinyuk , L. A. Kuzmichev , L. G. Sveshnikova

Noise is an important factor which when get added to an image reduces its quality and appearance. So in order to enhance the image qualities, it has to be removed with preserving the textural information and structural features of image.…

Computer Vision and Pattern Recognition · Computer Science 2019-01-23 Vivek Kumar , Atul Samadhiya

Arrays of Cherenkov telescopes typically use multi-level trigger schemes to keep the rate of random triggers from the night sky background low. At a first stage, individual telescopes produce a trigger signal from the pixel information in…

Instrumentation and Methods for Astrophysics · Physics 2019-08-14 M. Barcelo , J. A. Barrio , O. Blanch Bigas , J. Boix , C. Delgado , D. Herranz , R. Lopez-Coto , G. Martinez , L. A. Tejedor

We present a sophisticated likelihood reconstruction algorithm for shower-image analysis of imaging Cherenkov telescopes. The reconstruction algorithm is based on the comparison of the camera pixel amplitudes with the predictions from a…

Instrumentation and Methods for Astrophysics · Physics 2019-08-14 S. Vincent

The Cherenkov light produced in air showers largely contributes to the signal observed in ground-based gamma-ray and cosmic-ray observatories. Yet, no description of this phenomenon is available covering both regions of small and large…

High Energy Astrophysical Phenomena · Physics 2021-03-17 Luan Arbeletche , Vitor de Souza

Atmospheric \v{C}erenkov Technique is an established methodology to study $TeV$ energy gamma rays. However the challenging problem has always been the poor signal to noise ratio due to the presence of abundant cosmic rays. Several ingenious…

Astrophysics · Physics 2011-05-23 V. R. Chitnis , P. N. Bhat

New deep learning techniques present promising new analysis methods for Imaging Atmospheric Cherenkov Telescopes (IACTs) such as the upcoming Cherenkov Telescope Array (CTA). In particular, the use of Convolutional Neural Networks (CNNs)…

Instrumentation and Methods for Astrophysics · Physics 2021-03-31 Samuel Spencer , Thomas Armstrong , Jason Watson , Salvatore Mangano , Yves Renier , Garret Cotter

Cherenkov telescopes image the Cherenkov emission from air showers. A priori, it is not obvious if the `best' images are achieved by measuring Cherenkov photon angles, i.e. focusing the telescope at infinity, or by considering the air…

Astrophysics · Physics 2008-11-26 Werner Hofmann

In the atmospheric Cerenkov technique gamma rays are detected against the abundant background produced by hadronic showers. In order to improve the signal to noise ratio of the experiment, it is necessary to reject a significant fraction of…

Astrophysics · Physics 2011-08-17 V. R. Chitnis , P. N. Bhat

We present an analysis technique that uses the timing information of Cherenkov images from extensive air showers (EAS). Our emphasis is on distant, or large core distance gamma-ray induced showers at multi-TeV energies. Specifically,…

Instrumentation and Methods for Astrophysics · Physics 2011-05-03 V. Stamatescu , G. P. Rowell , J. Denman , R. W. Clay , B. R. Dawson , A. G. K. Smith , T. Sudholz , G. J. Thornton , N. Wild

Context. The response of imaging atmospheric Cherenkov telescopes to incident {\gamma}-ray-initiated showers in the atmosphere changes as the telescopes age due to exposure to light and weather. These aging processes affect the…

Over the last decade, the Imaging Air Cerenkov technique has proven itself to be an extremely powerful means to study very energetic gamma-radiation from a number of astrophysical sources in a regime which is not practically accessible to…

Astrophysics · Physics 2010-11-24 I. de la Calle Perez , S. D. Biller