J/A+A/493/317 Radio source selection for the ICRF (Lambert+, 2009)
On radio source selection for defining a stable celestial frame.
Lambert S.B., Gontier A.-M.
<Astron. Astrophys. 493, 317 (2009)>
=2009A&A...493..317L 2009A&A...493..317L
ADC_Keywords: Fundamental catalog ; Positional data ; VLBI
Keywords: reference systems - Earth
Abstract:
The most accurate realization of a quasi inertial reference frame,
the International Celestial Reference Frame (ICRF), is made of 212
defining extragalactic radio sources whose coordinates are determined
using VLBI observations. Recent studies demonstrated however that
using other sets of sources could improve the frame stability.
This study examines a simple radio source selection scheme to define
celestial reference frame axes more stable than the ones as currently
defined by the ICRF.
After having derived source coordinate time series from 26 years of
VLBI observations, we select the most suitable sources on the basis of
their positional variability (rms and slope), and observational
history. We determine the axis stability of the frame defined by the
selection, as well as its suitability for global geodetic VLBI
analyses, i.e., determination of Earth orientation parameters and
source and station coordinates.
Description:
The files contain the list of sources of the four subsets referred to
as 196 AMS, 200 AMS, 262 AMS, and 269 AMS in the above-mentioned
paper. The files also provide positional informations about the
sources taken in the ICRF-Ext.2 catalogue (J/AJ/127/3587).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list196.dat 79 196 List of the 196 AMS sources subset
list200.dat 79 200 List of the 200 AMS sources subset
list262.dat 79 260 List of the 262 AMS sources subset
list269.dat 79 267 List of the 269 AMS sources subset
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See also:
I/251 : VLBI International Celestial Reference Frame (ICRF) (Ma+, 1997)
J/AJ/127/3587 : VLBI ICRF. II (Fey+, 2004)
Byte-by-byte Description of file: list*.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [ICRF]
6- 21 A16 --- ICRF Radio source ICRF designation,
JHHMMSS.s+DDMMSS (1)
23- 30 A8 --- IERS Radio source IERS designation,
HHMM+DDd (B1950) (2)
32- 33 I2 h RAh Hour of right ascension (J2000) (3)
35- 36 I2 min RAm Minute of right ascension (J2000) (3)
38- 46 F9.6 s RAs Second of right ascension (J2000) (3)
48 A1 --- DE- Sign of the declination (J2000) (3)
49- 50 I2 deg DEd Degree of declination (J2000) (3)
52- 53 I2 arcmin DEm Arcminute of declination (J2000) (3)
54- 62 F9.5 arcsec DEs Arcsecond of declination (J2000) (3)
64- 71 F8.6 s e_RAs Error in right ascension (3)
73- 79 F7.5 arcsec e_DEs Error in declination (3)
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Note (1): ICRF Designations have been constructed from J2000.0 coordinates
with the format ICRF JHHMMSS.s+DDMMSS.
Note (2): IERS Designations refers to the previous designation constructed
at IERS from B1950 coordinates. The complete format, including acronym
and epoch, is IERS BHHMM+DDd.
Note (3): Coordinates and errors are those provided in the ICRF-Ext.2
catalogue (Fey et al., 2004, Cat. J/AJ/127/3587).
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Acknowledgements:
Sebastien Lambert, sebastien.lambert(at)obspm.fr
(End) Patricia Vannier [CDS] 10-Oct-2008