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We present a statistical method based on a maximum likelihood approach to constrain the number counts of extragalactic sources below the nominal flux-density limit of continuum imaging surveys. We extract flux densities from a radio map…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Ketron Mitchell-Wynne , Mario G. Santos , Jose Afonso , Matt J. Jarvis

We present an algorithm capable of detecting diffuse, dim sources of any size in an astronomical image. These sources often defeat traditional methods for source finding, which expand regions around points of high intensity. Extended…

Instrumentation and Methods for Astrophysics · Physics 2016-01-05 T. Butler-Yeoman , M. Frean , C. P. Hollitt , D. W. Hogg , M. Johnston-Hollitt

We present A-PHOT, a new publicly available code for performing aperture photometry on astronomical images, that is particularly well suited for multi-band extragalactic surveys. A-PHOT estimates the fluxes emitted by astronomical objects…

Instrumentation and Methods for Astrophysics · Physics 2019-02-20 E. Merlin , S. Pilo , A. Fontana , M. Castellano , D. Paris , V. Roscani , P. Santini , M. Torelli

We present an empirical correction of sky coordinates of X-ray photons obtained with the XIS aboard the Suzaku satellite to improve the source position accuracy and restore the point-spread function (PSF). The XIS images are known to have…

We describe an assembly of numerical tools to model the output data of the Planck satellite. These start with the generation of a CMB sky in a chosen cosmology, add in various foreground sources, convolve the sky signal with arbitrary, even…

Astrophysics · Physics 2009-11-11 Martin Reinecke , Klaus Dolag , Reinhard Hell , Matthias Bartelmann , Torsten Ensslin

We present a powerful new algorithm that combines both spatial information (event locations and the point spread function) and spectral information (photon energies) to separate photons from overlapping sources. We use Bayesian statistical…

Instrumentation and Methods for Astrophysics · Physics 2017-11-06 David E. Jones , Vinay L. Kashyap , David A. van Dyk

Transient detection and flux measurement via image subtraction stand at the base of time domain astronomy. Due to the varying seeing conditions, the image subtraction process is non-trivial, and existing solutions suffer from a variety of…

Instrumentation and Methods for Astrophysics · Physics 2016-10-12 Barak Zackay , Eran O. Ofek , Avishay Gal-Yam

All observations by the aperture photometer (PHT-P) and the far-infrared (FIR) camera section (PHT-C) of ISOPHOT included reference measurements against stable internal fine calibration sources (FCS) to correct for temporal drifts in…

MOPEX (MOsaicking and Point source EXtraction) is a package developed at the Spitzer Science Center for astronomical image processing. We report on the point source extraction capabilities of MOPEX. Point source extraction is implemented as…

Astrophysics · Physics 2009-11-13 David Makovoz , Francine R. Marleau

The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes…

Instrumentation and Methods for Astrophysics · Physics 2012-02-02 Johan Samsing , Alex G. Kim

Point-spread function (PSF) estimation in spatially undersampled images is challenging because large pixels average fine-scale spatial information. This is problematic when fine-resolution details are necessary, as in optimal photometry…

Instrumentation and Methods for Astrophysics · Physics 2021-02-03 Teresa Symons , Michael Zemcov , James Bock , Yun-Ting Cheng , Brendan Crill , Christopher Hirata , Stephanie Venuto

The estimation of the polarization $P$ of extragalactic compact sources in Cosmic Microwave Background images is a very important task in order to clean these images for cosmological purposes -- as, for example, to constrain the…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-07 D. Herranz , F. Argüeso , L. Toffolatti , A. Manjón-García , M. López-Caniego

Galaxy imaging surveys observe a vast number of objects that are affected by the instrument's Point Spread Function (PSF). Weak lensing missions, in particular, aim at measuring the shape of galaxies, and PSF effects represent an important…

Instrumentation and Methods for Astrophysics · Physics 2021-02-03 T. Liaudat , J. Bonnin , J. -L. Starck , M. A. Schmitz , A. Guinot , M. Kilbinger , S. D. J. Gwyn

We present a novel, easy-to-use method based on the photon-mapping technique to simulate photometric images of moving targets. Realistic images can be created in two passes: photon tracing and image rendering. The nature of light sources,…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 Junju Du , Shaoming Hu , Xu Chen , Hai Cao , Yuchen Jiang

Optimal error estimation is key to achieve accurate photometry and astrometry. Stellar fluxes and positions in high angular resolution images are typically measured with PSF fitting routines, such as StarFinder. However, the formal…

Instrumentation and Methods for Astrophysics · Physics 2022-08-12 E. Gallego-Cano , R. Schödel , A. T. Gallego-Calvente , A. M. Ghez

Astrometric measurements are significantly challenged by the relative motion between the point source and the telescope, primarily due to the difficulty in accurately determining the position of the point source at the mid-exposure moment.…

Instrumentation and Methods for Astrophysics · Physics 2025-03-11 Linpeng Wu , Qingfeng Zhang , Valéry Lainey , Nick Cooper , Nicolas Rambaux , Weiheng Zhu

We demonstrate a high-speed method to image objects through a thin scattering medium and around a corner. The method employs a reference object of known shape to retrieve the speckle-like point spread function of the scatterer. We extract…

We describe a rapid and direct method for regularizing, post-facto, the point-spread function (PSF) of a telescope or other imaging instrument, across its entire field of view. Imaging instruments in general blur point sources of light by…

Instrumentation and Methods for Astrophysics · Physics 2023-03-20 J. M. Hughes , C. E. DeForest , D. B. Seaton

We have developed a new Bayesian method to correct the flux densities of astronomical sources. The hybrid method combines a simulated likelihood to model survey selection together with an analytic source-count-based prior. The simulated…

Astrophysics of Galaxies · Physics 2020-04-29 Megan B. Gralla , Tobias A. Marriage

Incoherently illuminated or luminescent objects give rise to a low-contrast speckle-like pattern when observed through a thin diffusive medium, as such a medium effectively convolves their shape with a speckle-like point spread function…