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We investigate the accuracy of astrometric measurements with the VLT/FORS1 camera and consider potential applications. The study is based on two-epoch (2000 and 2002/2003) frame series of observations of a selected Galactic Bulge sky region…

Astrophysics · Physics 2009-11-13 P. F. Lazorenko , M. Mayor , M. Dominik , F. Pepe , D. Segransan , S. Udry

In this paper we test the astrometric precision of VLT/FORS2 observations using a serie of CCD frames taken in Galactic bulge area. A special reduction method based on symmetrization of reference fields was used to reduce the atmospheric…

Astrophysics · Physics 2009-11-11 Petro F. Lazorenko

We describe the astrometric reduction of images obtained with the FORS2/VLT camera in the framework of an astrometric planet search around 20 M/L-transition dwarfs. We present the correction of systematic errors, the achieved astrometric…

Solar and Stellar Astrophysics · Physics 2014-05-08 P. F. Lazorenko , J. Sahlmann , D. Segransan , E. L. Martin , M. Mayor , D. Queloz , S. Udry

We present an investigation of the stability of the two chips in the FORS2 camera CCD mosaic on the basis of astrometric observations of stars in 20 sky fields, some of which were monitored for four to seven years. We detected a smooth…

Instrumentation and Methods for Astrophysics · Physics 2026-01-14 P. F. Lazorenko , J. Sahlmann

ESO's two FOcal Reducer and low dispersion Spectrographs (FORS) are the primary imaging cameras for the VLT. Since they are not direct-imaging cameras, the accuracy of photometry which can routinely be obtained is limited by significant sky…

Astrophysics · Physics 2007-05-23 W. Freudling , M. Romaniello , F. Patat , P. Moller , E. Jehin , K. O'Brien

Images taken with modern detectors require calibration via flat fielding to obtain the same flux scale across the whole image. One method for obtaining the best possible flat fielding accuracy is to derive a photometric model from dithered…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 Lodovico Coccato , Daniel M. Bramich , Wolfram Freudling , Sabine Moehler

We compared positions of the Gaia first data release (DR1) secondary data set at its faint limit with CCD positions of stars in 20 fields observed with the VLT/FORS2 camera. The FORS2 position uncertainties are smaller than one…

Instrumentation and Methods for Astrophysics · Physics 2017-10-25 P. F. Lazorenko , J. Sahlmann

We investigate the limits of ground-based astrometry with adaptive optics using the core of the Galactic globular cluster M5. Adaptive optics systems provide near diffraction-limit imaging with the world's largest telescopes. The…

Astrophysics · Physics 2009-11-13 P. B. Cameron , M. C. Britton , S. R. Kulkarni

The paper discusses an assessment study about the impact of the distortions on the astrometric observations with the Extremely Large Telescope originated from the optics positioning errors and telescope instabilities. Optical simulations…

Instrumentation and Methods for Astrophysics · Physics 2018-06-06 Gabriele Rodeghiero , Jörg-Uwe Pott , Carmelo Arcidiacono , Davide Massari , Martin Glück , Hannes Riechert , Eric Gendron

With the aim of paving the road for future accurate astrometry with MICADO at the European-ELT, we performed an astrometric study using two different but complementary approaches to investigate two critical components that contribute to the…

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

We investigate how to quantitatively model the observed differential image motion (DIM) in relative astrometric observations. As a test bed we used differential astrometric observations from the FORS2 camera of the Very Large Telescope…

Instrumentation and Methods for Astrophysics · Physics 2024-08-13 P. F. Lazorenko , J. Sahlmann , M. Mayor , E. L. Martin

We perform photometric (the Lomb-Scargle periodogram, autocorrelation, and wavelet) and asteroseismic analyses of 92 Kepler solar-like main-sequence stars to understand the reliability of the measured stellar rotation periods. We focus on…

Solar and Stellar Astrophysics · Physics 2023-01-04 Yuting Lu , Othman Benomar , Shoya Kamiaka , Yasushi Suto

We reduced ESO's archival linear spectropolarimetry data (4000-9000\AA) of 6 highly polarized and 8 unpolarized standard stars observed between 2010 and 2016, for a total of 70 epochs, with the FOcal Reducer and low dispersion Spectrograph…

Instrumentation and Methods for Astrophysics · Physics 2016-10-12 Aleksandar Cikota , Ferdinando Patat , Stefan Cikota , Tamar Faran

The stable environment of space makes HST an excellent astrometric tool. Its diffraction-limited resolution allows it to distinguish and measure positions and fluxes for stars all the way to the center of most globular clusters. Apart from…

Solar and Stellar Astrophysics · Physics 2013-01-14 Andrea Bellini , Roeland P. van der Marel , Jay Anderson

The Chinese Space Station Survey Telescope (CSST) presents significant potential for high-precision astrometry. In this study, we show that the point spread function (PSF) modeled by the discrete PSF with Multi-Gaussian function can…

Instrumentation and Methods for Astrophysics · Physics 2025-08-15 Jialu Nie , Peng Wei , Zihuang Cao , Yibo Yan , Chao Liu , Hao Tian , Xin Zhang , Haijun Tian

We have derived a new photographic photometry and proper motions for 20000 stars with completeness to V = 18 in the direction of galactic center at the intermediate latitude (l = 3 deg,b = 47 deg; alpha(1950)=15h 18m, delta(1950) = +02deg…

Astrophysics · Physics 2007-05-23 D. K. Ojha , O. Bienayme , A. C. Robin , V. Mohan

The astrometric calibration of the Sloan Digital Sky Survey is described. For point sources brighter than r ~ 20 the astrometric accuracy is 45 milliarcseconds (mas) rms per coordinate when reduced against the USNO CCD Astrograph Catalog,…

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