Astrometric observation

2011 ◽  
Keyword(s):  
Astrometric Observation

scholarly journals Space Telescope Motion Limitations for Fine Guidance Sensor Astrometry

1986 ◽  
Vol 109 ◽  
pp. 643-647
Author(s):  
Alain Fresneau
Keyword(s):  
Power Spectrum ◽  
Sensor Data ◽  
Line Of Sight ◽  
Space Telescope ◽  
Preliminary Results ◽  
Complete Identification ◽  
Astrometric Observation

Basic Fine Guidance Sensor data have been simulated to correlate the Power Spectrum Densities (PSD) of the Space Telescope motion disturbances with the “seeing” of an astrometric target. The goal of this study is to describe whether a complete identification of the jitter of the line of sight during an astrometric observation is required to improve the precision of this observation. The present preliminary results indicate that the performance in Astrometry are close to the predictions.

scholarly journals Astrometric Observation of MACHO Gravitational Microlensing

1998 ◽  
Vol 502 (2) ◽  
pp. 538-549 ◽  
Author(s):  
A. F. Boden ◽  
M. Shao ◽  
D. Van Buren
Keyword(s):  
Gravitational Microlensing ◽  
Astrometric Observation

Overview of Gaia Multi-Color Photometry

2003 ◽  
Vol 12 (4) ◽  
Author(s):  
Erik Høg
Keyword(s):  
Optical System ◽  
Angular Resolution ◽  
Broad Band ◽  
Integration Time ◽  
High Angular Resolution ◽  
System A ◽  
Astrometric Observation ◽  
Medium Band ◽  
Effective Integration

AbstractGaia will obtain multi-color photometry for astrometric and astrophysical purposes. A photometry in five broad bands and with high angular resolution will be obtained after every astrometric observation of a star, especially for the sake of correcting slight astrometric chromaticity errors of the optical system. A separate smaller telescope will obtain photometry in eleven passbands of medium width designed to serve the astrophysical analysis of the mission results. The medium-band photometry (MBP) has less angular resolution, but much longer effective integration time than the broad-band photometry (BBP).

scholarly journals The Potential of Differential Astrometric Interferometry from the High Antarctic Plateau

2002 ◽  
Vol 19 (3) ◽  
pp. 318-322 ◽  
Author(s):  
James P. Lloyd ◽  
Ben R. Oppenheimer ◽  
James R. Graham
Keyword(s):  
Orbit Determination ◽  
Planet Detection ◽  
Antarctic Plateau ◽  
Narrow Angle ◽  
The Poor ◽  
Dual Beam ◽  
Infrared Background ◽  
Astrometric Observation ◽  
The Mean ◽  
The Antarctic

AbstractThe low infrared background and high atmospheric transparency are the principal advantages of Antarctic Plateau sites for astronomy. However, the poor seeing (between 1 and 3 as) negates much of the sensitivity improvements that the Antarctic atmosphere offers, compared to mid-latitude sites such as Mauna Kea or Cerro Paranal. The seeing at mid-latitude sites, though smaller in amplitude, is dominated by turbulence at altitudes of 10–20 km. Over the Antarctic Plateau, virtually no high altitude turbulence is present in the winter. The mean square error for an astrometric measurement with a dual-beam, differential astrometric interferometer in the very narrow angle regime is proportional to the integral of h2C2N(h). Therefore, sites at which the turbulence occurs only at low altitudes offer large gains in astrometric precision. We show that a modest interferometer at the South Pole can achieve 10 μ as differential astrometry 300 times faster than a comparable interferometer at a good mid-latitude site, in median conditions. Science programs that would benefit from such an instrument include planet detection and orbit determination, and astrometric observation of stars microlensed by dark matter candidates.

scholarly journals Astrometric Reduction of Cassini ISS Images of Enceladus in 2015 Based on Gaia DR1

2017 ◽  
Vol 12 (S330) ◽  
pp. 411-412
Author(s):  
Q. F. Zhang ◽  
V. Lainey ◽  
A. Vienne ◽  
N. J. Cooper ◽  
Q. Y. Peng ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Reference Frame ◽  
Gaia Dr1 ◽  
Astrometric Observation ◽  
Celestial Reference Frame ◽  
Right Ascension

AbstractThe Gaia DR1 catalogue stars are taken as reference ones to reduce the Cassini ISS images of Enceladus in 2015, and a total of 494 Cassini-centered astrometric observation are obtained in right ascension(α) and declination (δ) in the international Celestial Reference Frame(ICRF). Compared with JPL ephemerides SAT367, we derive that their mean residuals are a few tens meters in α*cos(δ) and a few kilometers in δ, and their standard deviation is not over 2 kilometers. Compared with the results from UCAC4 catalogue stars, The Gaia DR1 has the equivalent precision of reduction.

scholarly journals The second post-Newtonian light propagation and its astrometric measurement in the solar system

2015 ◽  
Vol 24 (07) ◽  
pp. 1550056 ◽  
Author(s):  
Xue-Mei Deng
Keyword(s):  
Light Propagation ◽  
Equations Of Motion ◽  
Relativistic Effects ◽  
Differential Measurement ◽  
Gravitational Fields ◽  
Astrometric Observation ◽  
Space Astrometry ◽  
Definition Of ◽  
Ppn Parameters ◽  
Near Future

The relativistic theories of light propagation are generalized by introducing two new parameters ς and η in the second post-Newtonian (2PN) order, in addition to the parametrized post-Newtonian (PPN) parameters γ and β. This new 2PN parametrized (2PPN) formalism includes the nonstationary gravitational fields and the influences of all kinds of relativistic effects. The multipolar components of gravitating bodies are taken into account as well at the first post-Newtonian (1PN) order. The equations of motion and their solutions of this 2PPN light propagation problem are obtained. Started from the definition of a measurable quantity, a gauge-invariant angle between the directions of two incoming photons for a differential measurement in astrometric observation is discussed and its formula is derived. For a precision level of a few microarcsecond (μas) for space astrometry missions in the near future, we further consider a model of angular measurement, the Laser Astrometric Test of Relativity (LATOR)-like missions. In this case, all terms with aimed at the accuracy of ~1μas are estimated.

scholarly journals Precision of Studies From Astrometric Observations: Recent Progress and Future Prospects

1990 ◽  
Vol 141 ◽  
pp. 145-146
Author(s):  
Z. X. Li
Keyword(s):  
Recent Progress ◽  
Systematic Errors ◽  
Future Prospects ◽  
Astrometric Observation

Recent progress of precision in astrometric studies is summarized and the weights of systematic errors in astrometric observation are analysed.

Astrometric observation of the Galactic LPVs with VERA; Mira and OH/IR stars

2018 ◽  
Vol 14 (S343) ◽  
pp. 476-477
Author(s):  
Akiharu Nakagawa ◽  
Tomoharu Kurayama ◽  
Gabor Orosz ◽  
Tomoaki Oyama ◽  
Takumi Nagayama ◽  
...  
Keyword(s):  
Long Period ◽  
Vlbi Observations ◽  
Ir Stars ◽  
Long Period Variables ◽  
Astrometric Observation

AbstractWe present studies of Long Period Variables (LPVs) in our Galaxy based on astrometric VLBI observations of H2O and SiO masers. The Galactic Miras and OH/IR stars are our main targets. For Miras, we present the distribution of the LPVs on the MK – log P plane. Galactic Miras show consistency with PLR in the LMC except for some fainter sources. Parallaxes of the LPVs determined from VLBI and Gaia are compared. There seems to be some offset.

scholarly journals ASTROMETRIC OBSERVATION OF MIRA VARIABLES WITH VERA

2015 ◽  
Vol 30 (2) ◽  
pp. 189-191
Author(s):  
AKIHARU NAKAGAWA ◽  
TOSHIHIRO OMODAKA ◽  
TOSHIHIRO HANDA ◽  
TATSUYA KAMEZAKI ◽  
VERA PROJECT
Keyword(s):  
Mira Variables ◽  
Astrometric Observation
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