scholarly journals Celestial Coordinate System and the FK5 Catalogue

1990 ◽  
Vol 141 ◽  
pp. 383-384
Author(s):  
A. P. Gulyaev
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Proper Motions

To study the motion of the celestial objects in a reference frame one should Know the evolution of the frame itself, In our case it the motion of the origin of coordinates and the proper motions of the objects, the system is based upon.

scholarly journals The Celestial Reference System in Relativistic Framework

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference System ◽  
Light Deflection ◽  
Coordinate Systems ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference System ◽  
Relativistic Framework

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.

scholarly journals The Relationships Between Various Techniques for Obtaining Proper Motions

1968 ◽  
Vol 1 ◽  
pp. 311-315
Author(s):  
C. A. Murray
Keyword(s):  
Reference Frame ◽  
Apparent Magnitude ◽  
Galactic Kinematics ◽  
Proper Motions

In many problems of galactic kinematics we need to know the proper motions of faint stars, as well as bright stars, within some well-defined reference frame. Generally speaking, the accuracy required is greater for faint stars on account of their larger distances. Techniques at present used for determining proper motions vary according to apparent magnitude, and it is clearly desirable that all methods should give results which are capable of reduction to a common frame.

scholarly journals Astrometry With Schmidt Telescopes

1984 ◽  
Vol 78 ◽  
pp. 217-224
Author(s):  
C A Murray
Keyword(s):  
Reference Frame ◽  
Proper Motions ◽  
Large Area ◽  
Full Field ◽  
Potential Value ◽  
Focal Surface ◽  
Single Plate ◽  
Trigonometric Parallaxes ◽  
The Absolute

Photographic astrometry, including work with Schmidt telescopes, can be divided into two main fields, (i) the measurement of positions of objects relative to a reference frame of stars with known celestial coordinates, and (ii) the measurement of relative proper motions and trigonometric parallaxes from a series of plates taken on the same field. The former demands a knowledge of the absolute transformation between angles on the sky and measurements on a plate, whereas in the latter we are only interested in differential transformations from plate to plate. The potential value of Schmidt telescopes for both these fields of astrometry lies in the large area of sky and range of magnitude which can be imaged on a single plate. The former advantage is however, to some extent offset by the curvature of the focal surface which means that, in order to utilize the full field the plates must be constrained to the form of the focal surface during exposure.

scholarly journals Proper Motions With Respect to the Extragalactic Reference Frame

1990 ◽  
Vol 141 ◽  
pp. 407-417
Author(s):  
A. R. Klemola
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Milky Way ◽  
Proper Motions ◽  
Stellar Proper Motions

The Lick proper motion program, one of several using galaxies as a reference frame, is summarized with a statement of work accomplished for the non-Milky Way sky. The problem of identifying relatively transparent regions at low galactic latitudes is discussed, with tabular results presented for 41 windows from the literature having observable galaxies. These fields may be helpful for attaching stellar proper motions directly to the extragalactic frame.

scholarly journals Astrometric Programs by the New Hamburg Plate Measuring Machine

1994 ◽  
Vol 161 ◽  
pp. 173-176
Author(s):  
Chr. de Vegt ◽  
L. Winter ◽  
N. Zacharias
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
High Accuracy ◽  
Proper Motions ◽  
Sky Surveys ◽  
Unique Data ◽  
Large Sets ◽  
Measuring Machine ◽  
First Time

With the new Hamburg astrometric measuring machine, large sets of plates can be digitized very quickly with submicrometer accuracy. In particular about 2000 plates of the AGK2-catalog, mean epoch 1930, can be remeasured now for the first time to their limiting magnitude, about B = 11. The new AGK2-data therefore will cover practically the whole AC-catalog and TYCHO-stars in the northern hemisphere. All plates will be reduced using the HIPPARCOS results as the reference frame when available in 1996. The new AGK2-data will provide a unique data base for the determination of high accuracy proper motions (about 2 mas/yr) of all TYCHO stars in the northern hemisphere. Furthermore, for the first time a dense reference frame for a final reduction of the Astrographic Catalog (AC) and the large deep sky surveys will be generated by this catalog. The inferior situation in the southern hemisphere will be addressed briefly.

scholarly journals Uses and Required Characteristics of Reference Frames for Galactic Astronomy

1986 ◽  
Vol 7 ◽  
pp. 51-54
Author(s):  
Roland Wielen
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Inertial System ◽  
Proper Motions ◽  
Upper Limits ◽  
Galactic Astronomy

AbstractGalactic astronomy requires mainly accurate proper motions of stars, referred to a system which represents an inertial system as closely as possible. We discuss the required accuracy, give an outlook on forthcoming reference frames of use for galactic astronomy, and discuss observationally determined upper limits on the rotation of the extra-galactic reference frame.

scholarly journals Accuracy Assessment of Hipparcos Optical and VLA Radio Positions of Stars

1993 ◽  
Vol 156 ◽  
pp. 377-380
Author(s):  
H. G. Walter ◽  
R. Hering ◽  
H. Lenhardt ◽  
Chr. deVegt ◽  
D.R. Florkowski ◽  
...  
Keyword(s):  
Radio Emission ◽  
Reference Frame ◽  
Accuracy Assessment ◽  
Optical Emission ◽  
Relative Orientation ◽  
Large Array ◽  
Proper Motions ◽  
Data Noise ◽  
Very Large Array ◽  
Radio Stars

Optical positions of some 30 radio stars derived from 12 months of HIPPARCOS measurements are compared with their radio positions obtained with the Very Large Array (VLA). — Once the lengths of arcs between optical and radio positions of pairs of stars are calculated the differences of the arcs are formed. They provide an estimate of the coincidence of the optical and radio emission centres. — From the comparison of optical and radio positions infinitesimal rotation angles of the HIPPARCOS frame with respect to the VLA extragalactic reference frame are determined by rigid rotations. After taking account of the relative orientation of the frames the standard deviations of the remaining residuals are approximately of the order of the VLA observation errors, thus demonstrating the reliability of the HIPPARCOS results. However, they also indicate some data noise very likely caused by the low accuracy of optical proper motions used to bridge the HIPPARCOS-radio epoch differences up to 9 years, and possible discrepancies of radio-optical emission centres of some stars.

scholarly journals Correction to Absolute Proper Motion Using the IAS-Galaxy Model

1990 ◽  
Vol 141 ◽  
pp. 427-429
Author(s):  
Kavan U. Ratnatunga
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Theoretical Models ◽  
Galactic Structure ◽  
Coordinate Frame ◽  
Proper Motions ◽  
Software Interface ◽  
The Galaxy ◽  
Galaxy Model ◽  
Star Catalogs

The IAS-Galaxy model (Ratnatunga, Bahcall and Casertano 1989) is a software interface between theoretical models of the Galaxy and observed kinematic distributions. It has been developed for analysis of many kinematic catalogs to study global galactic structure. In addition, the IASG model can be used to estimate corrections needed to derive absolute parallax and absolute proper motion by evaluating, on a star-by-star basis, the expected mean motion of the reference stars.A theoretical Galaxy model is defined on an inertial coordinate frame. Proper motions are measured in a reference frame defined by a fundamental catalog. The observed distribution of proper motions in star catalogs can be directly compared with the expected distributions evaluated using IASG to check the accuracy of the adopted reference frame in realizing the inertial coordinate frame in the sky.

ANALYSIS ON ATTITUDE POSITION OF EARTH CENTERED INERTIAL (ECI) BASED ON RAZAKSAT DATA

2015 ◽  
Vol 76 (12) ◽  
Author(s):  
Mohd Zamri Hasan ◽  
Sazali Yaacob ◽  
Amran Ahmed ◽  
Nor Hazadura Hamzah ◽  
Shamshul Bahar Yaakob ◽  
...  
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Earth Rotation ◽  
Attitude Determination ◽  
Three Dimensional ◽  
Measurement Data ◽  
Inertial Reference Frame ◽  
Determination System ◽  
Line Elements

Attitude determination system (ADS) is a process to control the orientation of satellite to make sure that the orientation of satellite is relative to inertial reference frame such as Earth. Earth Centered Inertial (ECI) is one of reference frame for satellite that determines the attitude in three dimensional spacecraft. Since RazakSAT orbits on earth, ECI coordinate system will be used for satellite relative to earth rotation. This paper is about the analysis on attitude position of ECI and velocity at X, Y and Z axis based on RazakSAT data. Satellite Tools Kit (STK) is used to estimate the attitude and velocity based on Two Line Elements (TLE) of RazakSAT. The result is compared with RazakSAT measurement data to observe the accuracy of estimation by using STK.

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