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We investigate the occurrence of multiple weak deflections in deep data sets which are used to detect galaxy-galaxy lensing. Using the galaxies in the HDF (North) for which both redshifts and rest-frame blue luminosities are known, we show…

Astrophysics · Physics 2007-05-23 C. O. Wright , T. G. Brainerd

Flexion-based weak gravitational lensing analysis is proving to be a useful adjunct to traditional shear-based techniques. As flexion arises from gradients across an image, analytic and numerical techniques are required to investigate…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Christopher J. Fluke , Paul D. Lasky

One of the most important parameters determining the sensitivity of X-ray telescopes is their effective area as a function of the X-ray energy. The computation of the effective area of a Wolter-I mirror, with either a single layer or…

Instrumentation and Methods for Astrophysics · Physics 2015-09-15 D. Spiga , V. Cotroneo

A discrete spherical harmonics method is developed for the radiative transfer problem in inhomogeneous polarized planar atmosphere illuminated at the top by a collimated sunlight while the bottom reflects the radiation. The method expands…

Instrumentation and Methods for Astrophysics · Physics 2018-02-07 Romuald Tapimo , Hervé Thierry Tagne Kamdem , David Yemele

The Rayleigh diffraction limit imposes a fundamental restriction on the resolution of direct imaging systems, hindering the identification of incoherent optical sources, such as celestial bodies in astronomy and fluorophores in bioimaging.…

Quantum Physics · Physics 2025-12-12 Danilo Triggiani , Cosmo Lupo

Monocular normal estimation aims to estimate the normal map from a single RGB image of an object under arbitrary lights. Existing methods rely on deep models to directly predict normal maps. However, they often suffer from 3D misalignment:…

Computer Vision and Pattern Recognition · Computer Science 2026-03-27 Zongrui Li , Xinhua Ma , Minghui Hu , Yunqing Zhao , Yingchen Yu , Qian Zheng , Chang Liu , Xudong Jiang , Song Bai

Deep anomaly detection models using a supervised mode of learning usually work under a closed set assumption and suffer from overfitting to previously seen rare anomalies at training, which hinders their applicability in a real scenario. In…

Image and Video Processing · Electrical Eng. & Systems 2020-10-26 Behzad Bozorgtabar , Dwarikanath Mahapatra , Guillaume Vray , Jean-Philippe Thiran

In an attempt to catch new X-ray transients while they are still bright, the data taken by XMM-Newton as it slews between targets is being processed and cross-correlated with other X-ray observations as soon as the slew data appears in the…

The short-term X-ray variability of Cyg X-1 can be interpreted as random occurrence of mini-flares known as the shots, whose physical nature is still unclear. We propose a new algorithm for shot identification in the X-ray light curve,…

High Energy Astrophysical Phenomena · Physics 2025-02-25 Jin Qin , Hua Feng , Lian Tao

We report on the production of a large area, shallow, sky survey, from XMM-Newton slews. The great collecting area of the mirrors coupled with the high quantum efficiency of the EPIC detectors have made XMM-Newton the most sensitive X-ray…

Astrophysics · Physics 2009-11-13 R. D. Saxton , A. M. Read , P. Esquej , M. J. Freyberg , B. Altieri , D. Bermejo

With consecutive bands in a wide range of wavelengths, hyperspectral images (HSI) have provided a unique tool for object detection task. However, existing HSI object detection methods have not been fully utilized in real applications, which…

Computer Vision and Pattern Recognition · Computer Science 2024-11-27 Hongqi Zhang , He Sun , Hongmin Gao , Feng Han , Xu Sun , Lianru Gao , Bing Zhang

Over the decades, astronomical X-ray telescopes have utilized the Wolter type-1 optical design, which provides stigmatic imaging in axial direction but suffers from coma and higher-order aberrations for off-axis sources. The…

Instrumentation and Methods for Astrophysics · Physics 2025-04-07 Neeraj K. Tiwari , Santosh V. Vadawale , N. P. S. Mithun

Wide area X-ray and far infrared surveys are a fundamental tool to investigate the link between AGN growth and star formation, especially in the low-redshift universe (z<1). The Herschel Terahertz Large Area survey (H-ATLAS) has covered 550…

High Energy Astrophysical Phenomena · Physics 2015-05-13 P. Ranalli , I. Georgantopoulos , A. Corral , L. Koutoulidis , M. Rovilos , F. J. Carrera , A. Akylas , A. Del Moro , A. Georgakakis , R. Gilli , C. Vignali

The imaging performance and sensitivity of an X-ray telescope when observing astrophysical sources are primarily governed by the optical design, geometrical uncertainties (figure errors, surface roughness, and mirror alignment…

Instrumentation and Methods for Astrophysics · Physics 2024-05-13 Neeraj K. Tiwari , Santosh V. Vadawale , N. P. S. Mithun , C. S. Vaishnava , Bharath Saiguhan

The search for exoplanets is an active field in astronomy, with direct imaging as one of the most challenging methods due to faint exoplanet signals buried within stronger residual starlight. Successful detection requires advanced image…

Instrumentation and Methods for Astrophysics · Physics 2025-03-24 Théo Bodrito , Olivier Flasseur , Julien Mairal , Jean Ponce , Maud Langlois , Anne-Marie Lagrange

Recently measured straylight PSFs in Hinode/SOT make granulation contrast in observed data and synthetic MHD data consistent. Data from earthbound telescopes also need accurate correction for straylight and fixed optical aberrations. We aim…

Instrumentation and Methods for Astrophysics · Physics 2012-01-16 M. G. Löfdahl , G. B. Scharmer

Weak gravitational lensing measurements based on photometry are limited by shape noise, the variance in the unknown unlensed orientations of the source galaxies. If the source is a disk galaxy with a well-ordered velocity field, however,…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-08 David Wittman , Matthew Self

This paper formulates a new problem, instance shadow detection, which aims to detect shadow instance and the associated object instance that cast each shadow in the input image. To approach this task, we first compile a new dataset with the…

Computer Vision and Pattern Recognition · Computer Science 2022-07-12 Tianyu Wang , Xiaowei Hu , Pheng-Ann Heng , Chi-Wing Fu

We have developed a new technique called Direct Shear Mapping (DSM) to measure gravitational lensing shear directly from observations of a single background source. The technique assumes the velocity map of an un-lensed, stably-rotating…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-26 Catherine O. de Burgh-Day , Edward N. Taylor , Rachel L. Webster , Andrew M. Hopkins

The XMM identification programme (XID) is accumulating Optical/IR images and spectra to identify thousands of XMM sources. The XID Database is the main repository of this data and permits easy selection and correlation of XMM X-ray and UV…

Astrophysics · Physics 2015-06-24 Houri Ziaeepour , Simon Rosen