Systematic Errors of High-Precision Photometric Catalogues

2002 ◽  
pp. 71-76
Author(s):  
Aleksey Mironov ◽  
Andrey Zakharov
Keyword(s):  
High Precision ◽  
Systematic Errors

scholarly journals Errors in high precision source position determination

1991 ◽  
Vol 131 ◽  
pp. 307-311
Author(s):  
Pedro Elosegui ◽  
Juan-Maria Marcaide ◽  
Irwin I. Shapiro
Keyword(s):  
Detailed Analysis ◽  
High Precision ◽  
Proper Motion ◽  
Systematic Errors ◽  
Source Position ◽  
Position Determination ◽  
The Core ◽  
Vlbi Observations

AbstractWe have made a detailed analysis of the systematic errors in the determination, from two sets of VLBI observations, of the position of the quasar 1038+528 A relative to the quasar 1038+528 B. This analysis confirms an apparent proper motion at λ=3.6cm of 26±8 μas/yr of the core of the quasar 1038+528 A relative to the quasar 1038+528 B.

scholarly journals Mitigating flicker noise in high-precision photometry

2020 ◽  
Vol 636 ◽  
pp. A70 ◽  
Author(s):  
S. Sulis ◽  
M. Lendl ◽  
S. Hofmeister ◽  
A. Veronig ◽  
L. Fossati ◽  
...  
Keyword(s):  
High Precision ◽  
Solar Disk ◽  
Colored Noise ◽  
Flicker Noise ◽  
Systematic Errors ◽  
Light Curves ◽  
Apparent Magnitude ◽  
Magnetic Cycle ◽  
Stellar Radius ◽  
Solar Observations

Context. In photometry, the short-timescale stellar variability (“flicker”), such as that caused by granulation and solar-like oscillations, can reach amplitudes comparable to the transit depth of Earth-sized planets and is correlated over the typical transit timescales. It can introduce systematic errors on the inferred planetary parameters when a small number of transits are observed. Aims. The objective of this paper is to characterize the statistical properties of the flicker noise and quantify its impact on the inferred transit parameters. Methods. We used the extensive solar observations obtained with SoHO/VIRGO to characterize flicker noise. We simulated realistic transits across the solar disk using SDO/HMI data and used these to obtain transit light curves, which we used to estimate the errors made on the transit parameters due to the presence of real solar noise. We make these light curves publicly available. To extend the study to a wider parameter range, we derived the properties of flicker noise using Kepler observations and studied their dependence on stellar parameters. Finally, we predicted the limiting stellar apparent magnitude for which the properties of the flicker noise can be extracted using high-precision CHEOPS and PLATO observations. Results. Stellar granulation is a stochastic colored noise, and is stationary with respect to the stellar magnetic cycle. Both the flicker correlation timescales and amplitudes increase with the stellar mass and radius. If these correlations are not taken into account when fitting for the parameters of transiting exoplanets, this can bias the inferred parameters. In particular, we find errors of up to 10% on the ratio between the planetary and stellar radius (Rp∕Rs) for an Earth-sized planet orbiting a Sun-like star. Conclusions. Flicker will significantly affect the inferred parameters of transits observed at high precision with CHEOPS and PLATO for F and G stars. Dedicated modeling strategies need to be developed to accurately characterize both the star and the transiting exoplanets.

High-precision absolute lattice parameter determination of SrTiO3, DyScO3 and NdGaO3 single crystals

2012 ◽  
Vol 68 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Martin Schmidbauer ◽  
Albert Kwasniewski ◽  
Jutta Schwarzkopf
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Room Temperature ◽  
Systematic Errors ◽  
Lattice Parameter ◽  
Parameter Determination ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Method

The lattice parameters of three perovskite-related oxides have been measured with high precision at room temperature. An accuracy of the order of 10−5 has been achieved by applying a sophisticated high-resolution X-ray diffraction technique which is based on the modified Bond method. The results on cubic SrTiO3 [a = 3.905268 (98) Å], orthorhombic DyScO3 [a = 5.442417 (54), b = 5.719357 (52) and c = 7.904326 (98) Å], and orthorhombic NdGaO3 [a = 5.428410 (54), b = 5.498407 (55) and c = 7.708878 (95) Å] are discussed in view of possible systematic errors as well as non-stoichiometry in the crystals.

scholarly journals HIGH PRECISION LATTICE QCD MEETS EXPERIMENT

2004 ◽  
Vol 19 (06) ◽  
pp. 877-886 ◽  
Author(s):  
P. LEPAGE ◽  
C. DAVIES
Keyword(s):  
Numerical Simulations ◽  
Lattice Qcd ◽  
High Precision ◽  
Systematic Errors ◽  
Qcd Vacuum ◽  
Comparison With Experiment ◽  
B Factory

We review recent results in lattice QCD from numerical simulations that allow for a much more realistic QCD vacuum than has been possible before. Comparison with experiment for a variety of hadronic quantities gives agreement to within statistical and systematic errors of 3%. We discuss the implications of this for future calculations in lattice QCD, particularly those which will provide input for B-factory experiments.

scholarly journals High Precision Stellar Photometry by CCDs. I

1995 ◽  
Vol 167 ◽  
pp. 173-173
Author(s):  
A. J. Penny
Keyword(s):  
High Precision ◽  
Percent Level ◽  
Systematic Errors ◽  
Uniform Illumination ◽  
Point Spread Functions ◽  
Stellar Photometry ◽  
The Third ◽  
Point Spread ◽  
Infra Red

This talk is about the limits to the precision of stellar photometry in comparing one star with another in a single CCD frame. This is concerned with bright stars, and concentrates on three problems at the 0.1 percent level of accuracy: how to flatfield; how to deal with varying point-spread-functions that vary across an image; how to deal with the fact that the response inside a pixel is not uniform. The first is the well-known difficulty of getting a uniform illumination across the CCD to use as a flatfield; the use of a rotatable CCD mounting and of drift-scanning is discussed. The second depends on the ability to detect and define small, but significant, changes in the PSF. The third is the fact that the pixels of optical CCDs can have non-uniformities inside them of ten percent, and these when folded with the PSF produce systematic errors significant at the 0.1 percent level; with infra-red arrays these problems can be much worse. The use of software to model these variations and reduce these errors is described.

scholarly journals Calibration of isotopologue-specific optical trace gas analysers: a practical guide

2018 ◽  
Vol 11 (11) ◽  
pp. 6189-6201 ◽  
Author(s):  
David W. T. Griffith
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Total Concentration ◽  
Systematic Errors ◽  
Trace Gas ◽  
Target Range ◽  
Isotopic Ratios ◽  
Spectroscopic Techniques ◽  
Practical Guide ◽  
Atmospheric Trace Gas

Abstract. The isotopic composition of atmospheric trace gases such as CO2 and CH4 provides a valuable tracer for the sources and sinks that contribute to atmospheric trace gas budgets. In the past, isotopic composition has typically been measured with high precision and accuracy by isotope ratio mass spectrometry (IRMS) offline and separately from real-time or flask-based measurements of concentrations or mole fractions. In recent years, development of infrared optical spectroscopic techniques based on laser and Fourier-transform infrared spectroscopy (FTIR) has provided high-precision measurements of the concentrations of one or more individual isotopologues of atmospheric trace gas species in continuous field and laboratory measurements, thus providing both concentration and isotopic measurements simultaneously. Several approaches have been taken to the calibration of optical isotopologue-specific analysers to derive both total trace gas amounts and isotopic ratios, converging into two different approaches: calibration via the individual isotopologues as measured by the optical device and calibration via isotope ratios, analogous to IRMS. This paper sets out a practical guide to the calculations required to perform calibrations of isotopologue-specific optical analysers, applicable to both laser and broadband FTIR spectroscopy. Equations to calculate the relevant isotopic and total concentration quantities without approximation are presented, together with worked numerical examples from actual measurements. Potential systematic errors, which may occur when all required isotopic information is not available, or is approximated, are assessed. Fortunately, in most such realistic cases, these systematic errors incurred are acceptably small and within the compatibility limits specified by the World Meteorological Organisation – Global Atmosphere Watch. Isotopologue-based and ratio-based calibration schemes are compared. Calibration based on individual isotopologues is simpler because the analysers fundamentally measure amounts of individual isotopologues, not ratios. Isotopologue calibration does not require a range of isotopic ratios in the reference standards used for the calibration, only a range of concentrations or mole fractions covering the target range. Ratio-based calibration leads to concentration dependence, which must also be characterised.

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