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Gaia's milli-arcsec (mas) astrometric precision allows systematic identification of optically-selected sub-kpc dual active galactic nuclei (AGN), off-nucleus AGN, and small-scale lensed quasars by `varstrometry' -- where variability-induced…

Astrophysics of Galaxies · Physics 2020-01-20 Hsiang-Chih Hwang , Yue Shen , Nadia Zakamska , Xin Liu

The Gaia Data Release 1 (GDR1) is a first, important step on the path of evolution of astrometric accuracy towards a much improved situation. Although asteroids are not present in GDR1, this intermediate release already impacts asteroid…

Earth and Planetary Astrophysics · Physics 2017-11-08 F. Spoto , P. Tanga , S. Bouquillon , J. Desmars , D. Hestroffer , F. Mignard , M. Altmann , D. Herald , J. Marchant , C. Barache , T. Carlucci , T. Lister , F. Taris

The first step toward doing high-precision astrometry is the measurement of individual stars in individual images, a step that is fraught with dangers when the images are undersampled. The key to avoiding systematic positional error in…

Astrophysics · Physics 2009-10-05 Jay Anderson , Ivan R. King

Gaia is ESA's ambitious space astrometry mission the main objective of which is to astrometrically and spectro-photometrically map 1000 Million celestial objects (mostly in our galaxy) with unprecedented accuracy. The announcement of…

Gaia Data Release 1 (Gaia DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. We give a…

Stochastic parametrisations are used in weather and climate models to improve the representation of unpredictable unresolved processes. When compared to a deterministic model, a stochastic model represents `model uncertainty', i.e., sources…

Atmospheric and Oceanic Physics · Physics 2020-04-22 Hannah M. Christensen

This paper contains the general data reduction methods used in processing the data from the Carlsberg Meridian Telescope CCD Drift Scan Survey. An efficient method to calibrate the fluctuations in the positions of the images caused by…

Astrophysics · Physics 2009-11-07 D. W. Evans , M. J. Irwin , L. Helmer

We investigated the reliability of the genetic algorithm which will be used to invert the photometric measurements of asteroids collected by the European Space Agency Gaia mission. To do that, we performed several sets of simulations for 10…

Earth and Planetary Astrophysics · Physics 2015-06-24 T. Santana-Ros , P. Bartczak , T. Michałowski , P. Tanga , A. Cellino

We are currently conceiving, through (MC) simulation, a multi-channel gamma detector array (TIARA for Time-of-flight Imaging ARrAy) for the online monitoring of protontherapy treatments. By measuring the Time-Of-Flight (TOF) between a beam…

Convection plays an essential role in the emerging intensity for many stars that will be observed by Gaia. Convective-related surface structures affect the shape, shift, and asymmetry of absorption lines, the phocentric and photometric…

Solar and Stellar Astrophysics · Physics 2011-12-13 A. Chiavassa , L. Bigot , F. Thevenin , R. Collet , G. Jasniewicz , Z. Magic , M. Asplund

The Gemini Planet Imager (GPI) is a near-infrared instrument that uses Adaptive Optics (AO), a coronagraph, and advanced data processing techniques to achieve very high contrast images of exoplanets. The GPI Exoplanet Survey (GPIES) is a…

Instrumentation and Methods for Astrophysics · Physics 2018-07-20 Melisa Tallis , Vanessa P. Bailey , Bruce Macintosh , Jeffrey K. Chilcote , Lisa A. Poyneer , Jean-Baptiste Ruffio , Thomas L. Hayward , Dmitry Savransky

Fast type-I migration of (proto)planets poses a challenging problem for the core accretion formation scenario. We found that the dust-induced ``Streaming Torque (ST)'' may slow down or even reverse the planet migration in \cite{Hou2024}.…

Earth and Planetary Astrophysics · Physics 2024-12-19 Qiang Hou , Cong Yu

Astrometric precision and knowledge of the point spread function are key ingredients for a wide range of astrophysical studies including time-delay cosmography in which strongly lensed quasar systems are used to determine the Hubble…

Instrumentation and Methods for Astrophysics · Physics 2021-09-22 Geoff C. -F. Chen , Tommaso Treu , Christopher D. Fassnacht , Sam Ragland , Thomas Schmidt , Sherry H. Suyu

In recent years, the underwater image formation model has found extensive use in the generation of synthetic underwater data. Although many approaches focus on scenes primarily affected by discoloration, they often overlook the model's…

Computer Vision and Pattern Recognition · Computer Science 2025-09-22 Vasiliki Ismiroglou , Malte Pedersen , Stefan H. Bengtson , Andreas Aakerberg , Thomas B. Moeslund

Due to dramatic improvements in the precision of astrometric measurements, the observation of light centroid shifts in observed stars due to intervening massive compact objects (`astrometric microlensing') will become possible in the near…

Astrophysics · Physics 2007-05-23 Martin Dominik , Kailash C. Sahu

This paper introduces a first-order method for solving optimal powered descent guidance (PDG) problems, that directly handles the nonconvex constraints associated with the maximum and minimum thrust bounds with varying mass and the pointing…

Optimization and Control · Mathematics 2024-04-02 Jiwoo Choi , Jong-Han Kim

Transition to turbulence dramatically alters the properties of fluid flows. In most canonical shear flows, the laminar flow is linearly stable and a finite-amplitude perturbation is necessary to trigger transition. Controlling transition to…

Fluid Dynamics · Physics 2020-05-20 Anton Pershin , Cedric Beaume , Steven M. Tobias

The scaled particle theory (SPT) approximation is applied for the study of the influence of a porous medium on the isotropic-nematic transition in a hard spherocylinder fluid. Two new approaches are developed in order to improve the…

Soft Condensed Matter · Physics 2018-04-02 M. F. Holovko , V. I. Shmotolokha

The class of transiting cold Jupiters, orbiting at $\gtrsim0.5-1.0$ au, is to-date underpopulated. Probing their atmospheric composition and physical characteristics is particularly valuable, as it allows for direct comparisons with the…

Earth and Planetary Astrophysics · Physics 2023-02-08 A. Sozzetti , P. Giacobbe , M. G. Lattanzi , M. Pinamonti

Accurate astrometry is crucial for determining orbits of near-Earth-asteroids (NEAs) and therefore better tracking them. This paper reports on a demonstration of 10 milliarcsecond-level astrometric precision on a dozen NEAs using the Pomona…

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