I/323 International Celestial Reference Frame 2, ICRF2 (Ma+, 2009)
The Second Realization of the International Celestial Reference Frame by
Very Long Baseline Interferometry.
Ma C., Arias F.E., Bianco G., Boboltz D.A., Bolotin S.L., Charlot P.,
Engelhardt G., Fey A.L., Gaume R.A., Gontier A.-M., Heinkelmann R.,
Jacobs C.S., Kurdubov S., Lambert S.B., Malkin Z.M., Nothnagel A.,
Petrov L., Skurikhina E., Sokolova J.R., Souchay J., Sovers O.J., Tesmer V.,
Titov O.A., Wang G., Zharov C.Barache V.E., Bockmann S., Collioud A.,
Gipson J.M., Gordon D., Lytvyn S.O., MacMillan D.S., Ojha R., Fey A.L.,
Gordon D., Jacobs C.S.
=2009ITN....35....1M 2009ITN....35....1M
ADC_Keywords: Fundamental catalog ; Positional data; VLBI
Abstract:
This Technical Note describes the generation by an international team
of the second realization of the International Celestial Reference
Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long
Baseline Interferometry (VLBI) observations. ICRF2 contains precise
positions of 3414 compact radio astronomical sources, more than five
times the number as in the first ICRF, hereafter ICRF1. Further, the
ICRF2 is found to have a noise floor of only 40µas, some 5-6 times
better than ICRF1, and an axis stability of 10µas, nearly twice as
stable as ICRF1. Alignment of ICRF2 with the International Celestial
Reference System (ICRS) was made using 138 stable sources common to
both ICRF2 and ICRF1-Ext2. Future maintenance of ICRF2 will be made
using a set of 295 new "defining" sources selected on the basis of
positional stability and the lack of extensive intrinsic source
structure. The stability of these 295 defining sources, and their more
uniform sky distribution eliminates the two largest weaknesses of
ICRF1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
icrf2.dat 136 3414 ICRF2 catalog
tn35.pdf 512 9516 PDF version of the paper (204 pages)
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See also:
http://www.iers.org/TN35 : On-line paper
http://aa.usno.navy.mil/AA/data/docs/ICRS_links.html : ICRS at USNO
I/251 : VLBI International Celestial Reference Frame (ICRF) (Ma+, 1997)
J/ApJS/141/13 : VLBA calibrator survey: VCS1 catalog (Beasley+, 2002)
J/AJ/126/2562 : Second VLBA calibrator survey: VCS2 (Fomalont+, 2003)
J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005)
J/AJ/131/1872 : Fourth VLBA calibrator survey: VCS4 (Petrov+, 2006)
J/AJ/133/1236 : Fifth VLBA calibrator survey: VCS5 (Kovalev+, 2007)
J/AJ/136/580 : Sixth VLBA calibrator survey: VCS6 (Petrov+, 2008)
Byte-by-byte Description of file: icrf2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ICRF International Celestial Reference Frame name,
(JHHMMSS.s+DDMMSS)
18- 25 A8 --- IVS International VLBI Service name,
(HHMM+DDd, B1950 equinox)
27- 34 A8 --- IERS International Earth Rotation and Reference
Systems Service name (HHMM+DDd, B1950 equinox)
36 A1 --- fl [DVN] Flag on source role (1)
38- 39 I2 h RAh Right Ascension (J2000)
41- 42 I2 min RAm Right Ascension (J2000)
44- 54 F11.8 s RAs Right ascension (J2000)
56 A1 --- DE- Declination sign (J2000)
57- 58 I2 deg DEd Declination (J2000)
60- 61 I2 arcmin DEm Declination (J2000)
63- 72 F10.7 arcsec DEs Declination (J2000)
74- 83 F10.8 s e_RAs Inflated formal error in Right Ascension
85- 93 F9.7 arcsec e_DEs Inflated formal error in Declination
95-100 F6.3 --- Corr [-1/1] Correlation between RA and Dec
102-108 F7.1 d Ep Mean observation epoch (MJD)
110-116 F7.1 d Of First observation epoch (MJD)
118-124 F7.1 d Ol Last observation epoch (MJD)
126-129 I4 --- Nexp Number of VLBI sessions
131-136 I6 --- Nobs Number of VLBI observations
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Note (1): Flag as follows:
D = defining source (all defining sources are non-VCS sources)
V = VCS source (Very long baseline array calibrator survey)
N = non-VCS source
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Acknowledgements:
Jean Souchay, Jean.Souchay(at)obspm.fr
(End) Patricia Vannier [CDS] 06-Jun-2013