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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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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)
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).
Acknowledgements: Sebastien Lambert, sebastien.lambert(at)obspm.fr
(End) Patricia Vannier [CDS] 10-Oct-2008
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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